Hopkins, Philip F., Younger, Joshua D., Hayward, Christopher C., Narayanan, Desika, Hernquist, Lars
We use a novel method to predict the contribution of normal star-forming galaxies, merger-induced bursts, and obscured AGN, to IR luminosity functions (LFs) and global SFR densities. We use empirical...
Hopkins, Philip F., Hernquist, Lars
The centers of bulges are formed dissipationally via gas inflows over short timescales: the 'starburst' mode of star formation (SF). Recent work has shown that detailed observations can be used to...
A Physical Model for z~2 Dust Obscured Galaxies (2009)
Narayanan, Desika, Dey, Arjun, Hayward, Christopher, Cox, Thomas J., Bussmann, R. Shane, Brodwin, Mark, ...
We present a physical model for the origin of z~2 Dust-Obscured Galaxies (DOGs), a class of high-redshift ULIRGs selected at 24 micron which are particularly optically faint (F24/FR>1000). By...
A Measurement of Small Scale Structure in the 2.2 < z < 4.2 Lyman-alpha Forest (2009)
Lidz, Adam, Dall'Aglio, Aldo, McQuinn, Matthew, Fechner, Cora, Zaldarriaga, Matias, ...
The amplitude of fluctuations in the Ly-a forest on small spatial scales is sensitive to the temperature of the IGM and its spatial fluctuations. The temperature of the IGM and its spatial variations...
Discriminating Between the Physical Processes that Drive Spheroid Size Evolution (2009)
Hopkins, Philip F., Bundy, Kevin, Hernquist, Lars, Wuyts, Stijn, Cox, Thomas J.
Massive galaxies at high-z have smaller effective radii than those today, but similar central densities. Their size growth therefore relates primarily to the evolving abundance of low-density...
Substructure depletion in the Milky Way halo by the disk (2009)
D'Onghia, Elena, Springel, Volker, Hernquist, Lars, Keres, Dusan
We employ numerical simulations and simple analytical estimates to argue that dark matter substructures orbiting in the inner regions of the Galaxy can be efficiently destroyed by disk shocking, a...
Resonant stripping as the origin of dwarf spheroidal galaxies (2009)
D'Onghia, Elena, Besla, Gurtina, Cox, Thomas J., Hernquist, Lars
Dwarf spheroidal galaxies are the most dark matter dominated systems in the nearby Universe and their origin is one of the outstanding puzzles of how galaxies form. Dwarf spheroidals are poor in gas...
Collisional Stripping and Disruption of Super-Earths (2009)
Marcus, Robert A., Stewart, Sarah T., Sasselov, Dimitar, Hernquist, Lars
The final stage of planet formation is dominated by collisions between planetary embryos. The dynamics of this stage determine the orbital configuration and the mass and composition of planets in the...
Mergers and Bulge Formation in Lambda-CDM: Which Mergers Matter? (2009)
Hopkins, Philip F., Bundy, Kevin, Croton, Darren, Hernquist, Lars, Keres, Dusan, Khochfar, Sadegh, ...
We use a suite of semi-empirical models to predict galaxy merger rates and contributions to bulge growth as functions of merger mass, redshift, and mass ratio. The models use empirical halo...
Wuyts, Stijn, Franx, Marijn, Cox, Thomas J., Schreiber, Natascha M. Forster, Hayward, Christopher C., Hernquist, Lars, ...
We present a comparison between the observed color distribution, number and mass density of massive galaxies at 1.5 < z < 3 and a model by Hopkins et al. that relates the quasar and galaxy population...
The Star-Forming Molecular Gas in High Redshift Submillimeter Galaxies (2009)
Narayanan, Desika, Cox, Thomas J., Hayward, Christopher, Younger, Joshua D., Hernquist, Lars
We present a model for the CO molecular line emission from high redshift Submillimeter Galaxies (SMGs). By combining hydrodynamic simulations of gas rich galaxy mergers with the polychromatic...
Seeding the formation of cold gaseous clouds in Milky Way size halos (2009)
We use one of the highest resolution cosmological SPH simulations to date to demonstrate that cold gaseous clouds form around Milky Way size galaxies. We further explore mechanisms responsible for...
The formation of the first stars and galaxies (2009)
Bromm, Volker, Yoshida, Naoki, Hernquist, Lars, McKee, Christopher F.
Observations made using large ground-based and space-borne telescopes have probed cosmic history all the way from the present-day to a time when the Universe was less than a tenth of its present age....
The Formation of High Redshift Submillimeter Galaxies (2009)
Narayanan, Desika, Hayward, Christopher C., Cox, Thomas J., Hernquist, Lars, Jonsson, Patrik, Younger, Joshua D., ...
We describe a model for the formation of \zsim 2 Submillimeter Galaxies (SMGs) which simultaneously accounts for both average and bright SMGs while providing a reasonable match to their mean observed...
Wuyts, Stijn, Franx, Marijn, Cox, Thomas J., Hernquist, Lars, Hopkins, Philip F., Robertson, Brant E., ...
We present a detailed analysis of our ability to determine stellar masses, ages, reddening and extinction values, and star formation rates of high-redshift galaxies by modeling broad-band SEDs with...
Hopkins, Philip F., Somerville, Rachel S., Cox, Thomas J., Hernquist, Lars, Jogee, Shardha, Keres, Dusan, ...
Transformation of disks into spheroids via mergers is a well-accepted element of galaxy formation models. However, recent simulations have shown that bulge formation is suppressed in increasingly...
Are Most Low-Luminosity AGN Really Obscured? (2009)
Hopkins, Philip F., Hickox, Ryan, Quataert, Eliot, Hernquist, Lars
At low Eddington ratio (mdot), two effects make it harder to detect AGN given some selection criteria. First, they may transition to a radiatively inefficient state, changing SED shape and...
Lee, Tae Song, Nagamine, Kentaro, Hernquist, Lars, Springel, Volker
We calculate the cross-correlation function (CCF) between damped Ly-alpha systems (DLAs) and Lyman break galaxies (LBGs) using cosmological hydrodynamic simulations at z=3. We compute the CCF with...
A Characteristic Division Between the Fueling of Quasars and Seyferts: Five Simple Tests (2008)
Hopkins, Philip F., Hernquist, Lars
Given the existence of the M_BH-sigma relation, models of self-regulated black hole (BH) growth require both a fuel supply and growth of the host bulge to deepen the potential, or else the system...
Thermal and magnetic properties of neutron stars (2008)
The interaction of the magnetic field with the heat flux in neutron stars is investigated. It is proposed that the magnetic field develops as a result of thermal processes in the liquid and solid...
The Binarity of the Magellanic Clouds and the Formation of the Magellanic Stream (2008)
Besla, Gurtina, Kallivayalil, Nitya, Hernquist, Lars, Van Der Marel, Roeland P., Cox, T. J., Robertson, Brant, ...
The HST proper motion (PM) measurements of the Clouds have severe implications for their interaction history with the Milky Way (MW) and with each other. The Clouds are likely on their first passage...
Hopkins, Philip F., Hernquist, Lars
We use the observed distribution of Eddington ratios as a function of supermassive black hole (BH) mass to constrain models of AGN lifetimes and lightcurves. Given the observed AGN luminosity...
Somerville, Rachel S., Hopkins, Philip F., Cox, Thomas J., Robertson, Brant E., Hernquist, Lars
We present a new semi-analytic model that self-consistently traces the growth of supermassive black holes (BH) and their host galaxies within the context of the LCDM cosmological framework. In our...
Protostar Formation in the Early Universe (2008)
Yoshida, Naoki, Omukai, Kazuyuki, Hernquist, Lars
The nature of the first generation of stars in the Universe remains largely unknown. Observations imply the existence of massive primordial stars early in the history of the universe, and the...
HeII Reionization and its Effect on the IGM (2008)
McQuinn, Matthew, Lidz, Adam, Zaldarriaga, Matias, Hernquist, Lars, Hopkins, Philip F., Dutta, Suvendra, ...
Observations of the intergalactic medium (IGM) suggest that quasars reionize HeII in the IGM at z ~ 3. We have run a set of 190 and 430 comoving Mpc simulations of HeII being reionized by quasars to...
Hopkins, Philip F., Hernquist, Lars, Cox, Thomas J., Keres, Dusan, Wuyts, Stijn
We develop a model for the origins and redshift evolution of spheroid scaling relations. We consider spheroid sizes, velocity dispersions, masses, profile shapes (Sersic indices), and black hole (BH)...
Simulations of XUV Disks with a Star Formation Density Threshold (2008)
Bush, Stephanie J., Cox, T. J., Hernquist, Lars, Thilker, David, Younger, Joshua D.
The outer regions of disk galaxies show a drop-off in optical and Halpha emission, suggesting a star formation threshold radius, assumed to owe to a critical surface density below which star...
Dissipation and the Fundamental Plane: Observational Tests (2008)
Hopkins, Philip F., Cox, Thomas J., Hernquist, Lars
We develop observational tests of the idea that dissipation in gas-rich mergers produces the fundamental plane (FP) and related correlations obeyed by ellipticals. The FP 'tilt' implies lower-mass...
Incidence Rate of GRB-host-DLAs at High Redshift (2008)
Nagamine, Kentaro, Zhang, Bing, Hernquist, Lars
We study the incidence rate of damped Ly-a systems associated with the host galaxies of gamma-ray bursts (GRB-host-DLAs) as functions of neutral hydrogen column density (N_HI) and projected star...
Hopkins, Philip F., Hernquist, Lars, Cox, Thomas J., Younger, Joshua D., Besla, Gurtina
Previous models of galactic disk heating in interactions invoke restrictive assumptions not necessarily valid in modern LCDM contexts: that satellites and orbits are rigid and circular, with slow...
Dissipation and Extra Light in Galactic Nuclei: III. 'Core' Ellipticals and 'Missing' Light (2008)
Hopkins, Philip F., Lauer, Tod R., Cox, Thomas J., Hernquist, Lars, Kormendy, John
We investigate how 'extra' central light in the surface brightness profiles of cusp ellipticals relates to the profiles of ellipticals with cores. Cusp elliptical envelopes are formed by violent...
How Do Disks Survive Mergers? (2008)
Hopkins, Philip F., Cox, Thomas J., Younger, Joshua D., Hernquist, Lars
We develop a physical model for how galactic disks survive and/or are destroyed in interactions. Based on dynamical arguments, we show gas primarily loses angular momentum to internal torques in a...
Probing Reionization with the 21 cm-Galaxy Cross Power Spectrum (2008)
Lidz, Adam, Zahn, Oliver, Furlanetto, Steven, McQuinn, Matthew, Hernquist, Lars, Zaldarriaga, Matias
The cross-correlation between high redshift galaxies and 21 cm emission from the high redshift intergalactic medium (IGM) promises to be an excellent probe of the Epoch of Reionization (EoR). On...
The Star Formation Rate - Dense Gas Relation in the Nuclei of Nearby Galaxies (2008)
Narayanan, Desika, Cox, Thomas J., Hernquist, Lars
We investigate the relationship between the star formation rate (SFR) and dense molecular gas mass in the nuclei of galaxies. To do this, we utilize the observed 850 micron luminosity as a proxy for...
Dissipation and Extra Light in Galactic Nuclei: II. 'Cusp' Ellipticals (2008)
Hopkins, Philip F., Cox, Thomas J., Dutta, Suvendra N., Hernquist, Lars, Kormendy, John, Lauer, Tod R.
We study the origin and properties of 'extra' or 'excess' central light in the surface brightness profiles of cusp or power-law ellipticals. Dissipational mergers give rise to two-component profiles:...
The Self-Regulated Growth of Supermassive Black Holes (2008)
Younger, Joshua D., Hopkins, Philip F., Cox, T. J., Hernquist, Lars
We present a series of simulations of the self--regulated growth of supermassive black holes (SMBHs) in galaxies via three different fueling mechanisms: major mergers, minor mergers, and disk...
Croft, Rupert A. C., Di Matteo, Tiziana, Springel, Volker, Hernquist, Lars
We explore galaxy properties and their link with environment and clustering using a population of ~1000 galaxies formed in a high resolution hydrodynamic simulation of the Lambda CDM cosmology. At...
On the Origin of Dynamically Cold Rings Around the Milky Way (2008)
Younger, Joshua D., Besla, Gurtina, Cox, T. J., Hernquist, Lars, Robertson, Brant, Willman, Beth
We present a scenario for the production of dynamically cold rings around the Milky Way via a high-eccentricity, flyby encounter. These initial conditions are more cosmologically motivated than those...
Dissipation and Extra Light in Galactic Nuclei: I. Gas-Rich Merger Remnants (2008)
Hopkins, Philip F., Hernquist, Lars, Cox, Thomas J., Dutta, Suvendra N., Rothberg, Barry
We study the origin and properties of 'extra' or 'excess' central light in the surface brightness profiles of gas-rich merger remnants. Combining a large set of hydrodynamical simulations with data...
Lyman-alpha Emitters and Lyman-break Galaxies at z=3-6 in Cosmological SPH Simulations (2008)
Nagamine, Kentaro, Ouchi, Masami, Springel, Volker, Hernquist, Lars
We study the properties of Lyman-alpha emitters (LAEs) and Lyman-break galaxies (LBGs) at z=3-6 using cosmological SPH simulations. We investigate two simple scenarios for explaining the observed...
Direct cosmological simulations of the growth of black holes and galaxies (2008)
Di Matteo, Tiziana, Colberg, Jörg, Springel, Volker, Hernquist, Lars, Sijacki, Debora
Li, Yuexing, Hopkins, Philip F., Hernquist, Lars, Finkbeiner, Douglas P., Cox, Thomas J., Springel, Volker, ...
Somerville, Rachel S., Hopkins, Philip F., Cox, Thomas J., Robertson, Brant E., Hernquist, Lars
We present a new semi-analytic model that self-consistently traces the growth of supermassive black holes (BH) and their host galaxies within the context of the Lambda cold dark matter (LambdaCDM)...
Yuexing Li, Philip F. Hopkins, Lars Hernquist, Douglas P. Finkbeiner, Thomas J. Cox, Volker Springel, ...
The detection of large quantities of dust in z ∼ 6 quasars by infrared and radio surveys presents puzzles for the formation and evolution of dust in these early systems. Previously (Li et al....
Detecting the Rise and Fall of 21 cm Fluctuations with the Murchison Widefield Array (2007)
Lidz, Adam, Zahn, Oliver, McQuinn, Matthew, Zaldarriaga, Matias, Hernquist, Lars
We forecast the sensitivity with which the Murchison Widefield Array (MWA) can measure the 21 cm power spectrum of cosmic hydrogen, using radiative transfer simulations to model reionization and the...
Photoionization, Numerical Resolution, And Galaxy Formation (2007)
David Weinberg Ohio, David H. Weinberg, Lars Hernquist, Neal Katz
Using cosmological simulations that incorporate gas dynamics and gravitational forces, we investigate the influence of photoionization by an ultraviolet radiation background on the formation of...
Simulating Cosmic Structure Formation (2007)
David Weinberg, Neal Katz, Lars Hernquist
. We describe cosmological simulation techniques and their application to studies of cosmic structure formation, with particular attention to recent hydrodynamic simulations of structure in the high...
Testing Cosmological Models Against The Abundance Of Damped Lyman-Alpha Absorbers (2007)
Jeffrey Gardner, Neal Katz, David H. Weinberg, Lars Hernquist
We calculate the number of damped Lyff absorbers expected in various popular cosmological models as a function of redshift and compare our predictions with observed abundances. The Press-Schechter...
Tidal Shocking by Extended Mass Distributions (2007)
Oleg Gnedin, Lars Hernquist, Jeremiah P. Ostriker
We derive expressions for the tidal field exerted by a spherically symmetric galaxy having an extended mass distribution, and use our analysis to calculate tidal perturbations and heating of stars in...
The Population Of Damped Lyman-Alpha And Lyman Limit Systems In The Cold Dark Matter Model (2007)
Jeffrey Gardner, Neal Katz, Lars Hernquist, David H. Weinberg
Lyman limit and damped Lyff absorption systems probe the distribution of collapsed, cold gas at high redshift. Numerical simulations that incorporate gravity and gas dynamics can predict the...
Molecular Star Formation Rate Indicators in Galaxies (2007)
Narayanan, Desika, Cox, Thomas J., Shirley, Yancy, Dave, Romeel, Hernquist, Lars, Walker, Christopher K.
We derive a physical model for the observed relations between star formation rate (SFR) and molecular line (CO and HCN) emission in galaxies, and show how these observed relations are reflective of...
Probing the Neutral Fraction of the IGM with GRBs during the Epoch of Reionization (2007)
McQuinn, Matthew, Lidz, Adam, Zaldarriaga, Matias, Hernquist, Lars, Dutta, Suvendra
We show that near-infrared observations of the red side of the Ly-alpha line from a single gamma ray burst (GRB) afterglow cannot be used to constrain the global neutral fraction of the intergalactic...
The Role of Galactic Winds on Molecular Gas Emission from Galaxy Mergers (2007)
Narayanan, Desika, Cox, T. J., Kelly, Brandon, Dave, Romeel, Hernquist, Lars, Di Matteo, Tiziana, ...
We assess the impact of starburst and AGN feedback-driven winds on the CO emission from galaxy mergers, and, in particular, search for signatures of these winds in the simulated CO morphologies and...
Younger, Joshua D., Huang, Jia-Sheng, Fazio, Giovanni G., Cox, Thomas J., Lai, Kamson, Hopkins, Philip F., ...
We present the rest-frame ultraviolet through near infrared spectral energy distribution for an interacting Lyman break galaxy at a redshift z=4.42, the highest redshift merging system known with...
Antitruncated Stellar Disks via Minor Mergers (2007)
Younger, Joshua D., Cox, T. J., Seth, Anil C., Hernquist, Lars
We use hydrodynamic simulations of minor mergers of galaxies to investigate the nature of surface brightness excesses at large radii observed in some spiral galaxies: antitruncated stellar disks. We...
An Observed Fundamental Plane Relation for Supermassive Black Holes (2007)
Hopkins, Philip F., Hernquist, Lars, Cox, Thomas J., Robertson, Brant, Krause, Elisabeth
We study observed correlations between supermassive black hole (BHs) and the properties of their host galaxies, and show that the observations define a BH 'fundamental plane' (BHFP), of the form M_BH...
The Nature of CO Emission From z~6 Quasars (2007)
Narayanan, Desika, Li, Yuexing, Cox, Thomas J., Hernquist, Lars, Hopkins, Philip, Chakrabarti, Sukanya, ...
We investigate the nature of CO emission from z~6 quasars by combining non-LTE radiative transfer calculations with merger-driven models of z~6 quasar formation that arise naturally in LCDM...
Formation of Massive Primordial Stars in a Reionized Gas (2007)
Yoshida, Naoki, Omukai, Kazuyuki, Hernquist, Lars
We use cosmological hydrodynamic simulations with unprecedented resolution to study the formation of primordial stars in an ionized gas at high redshifts. Our approach includes all the relevant...
Li, Yuexing, Hopkins, Philip F., Hernquist, Lars, Finkbeiner, Douglas P., Cox, Thomas J., Springel, Volker, ...
The detection of large quantities of dust in z ~ 6 quasars by infrared and radio surveys presents puzzles for the formation and evolution of dust in these early systems. Previously (Li et al. 2007),...
Hopkins, Philip F., Hernquist, Lars, Cox, Thomas J., Keres, Dusan
(Abridged) We develop a model for the cosmological role of mergers in the evolution of starbursts, quasars, and spheroidal galaxies. Combining halo mass functions (MFs) with empirical halo occupation...
Hopkins, Philip F., Cox, Thomas J., Keres, Dusan, Hernquist, Lars
(Abridged) We develop and test a model for the cosmological role of mergers in the formation and quenching of red, early-type galaxies. Making the ansatz that star formation is quenched after a...
A unified model for AGN feedback in cosmological simulations of structure formation (2007)
Sijacki, Debora, Springel, Volker, Di Matteo, Tiziana, Hernquist, Lars
We discuss a numerical model for black hole growth and its associated feedback processes that for the first time allows cosmological simulations of structure formation to self-consistently follow the...
Direct cosmological simulations of the growth of black holes and galaxies (2007)
Di Matteo, Tiziana, Colberg, Joerg, Springel, Volker, Hernquist, Lars, Sijacki, Debora
We investigate the coupled formation and evolution of galaxies and their embedded supermassive black holes using state-of-the-art hydrodynamic simulations of cosmological structure formation. For the...
Studying Reionization with Ly-alpha Emitters (2007)
McQuinn, Matthew, Hernquist, Lars, Zaldarriaga, Matias, Dutta, Suvendra
We show that observations of high-redshift Ly-alpha emitters (LAEs) have the potential to provide definitive evidence for reionization in the near future. Using 200 Mpc radiative transfer...
Quasar Proximity Zones and Patchy Reionization (2007)
Lidz, Adam, McQuinn, Matthew, Zaldarriaga, Matias, Hernquist, Lars, Dutta, Suvendra
Lyman-alpha forest absorption spectra towards quasars at z ~ 6 show regions of enhanced transmission close to their source. Several authors have argued that the apparently small sizes of these...
Photometric Properties of the Most Massive High-Redshift Galaxies (2007)
Robertson, Brant, Li, Yuexing, Cox, Thomas J., Hernquist, Lars, Hopkins, Philip F.
We calculate the observable properties of the most massive high-redshift galaxies in the hierarchical formation scenario where stellar spheroid and supermassive black hole growth are fueled by...
Are the Magellanic Clouds on their First Passage about the Milky Way? (2007)
Besla, Gurtina, Kallivayalil, Nitya, Hernquist, Lars, Robertson, Brant, Cox, T. J., Van Der Marel, Roeland P., ...
Recent proper motion measurements of the Large and Small Magellanic Clouds (LMC and SMC, respectively) by Kallivayalil et al (2006a,b) suggest that the 3D velocities of the Clouds are substantially...
A Theoretical Interpretation of the Black Hole Fundamental Plane (2007)
Hopkins, Philip F., Hernquist, Lars, Cox, Thomas J., Robertson, Brant, Krause, Elisabeth
We examine the origin and evolution of correlations between properties of supermassive black holes (BHs) and their host galaxies using simulations of major galaxy mergers, including the effects of...
Distribution of damped Lyα absorbers in a Λ cold dark matter universe (2007)
Nagamine, Kentaro, Wolfe, Arthur M., Hernquist, Lars, Springel, Volker
Formation of z~6 quasars from hierarchical galaxy mergers (2007)
Li, Yuexing, Hernquist, Lars, Robertson, Brant, Cox, Thomas J., Hopkins, Philip F., Springel, Volker, ...
A unified model for AGN feedback in cosmological simulations of structure formation (2007)
Sijacki, Debora, Springel, Volker, Di Matteo, Tiziana, Hernquist, Lars
The Co-Formation of Spheroids and Quasars Traced in their Clustering (2006)
Hopkins, Philip F., Lidz, Adam, Hernquist, Lars, Coil, Alison L., Myers, Adam D., Cox, Thomas J., ...
We compare observed clustering of quasars and galaxies as a function of redshift, mass, luminosity, & color/morphology, to constrain models of quasar fueling and spheroid-BH co-evolution. High...
An Evolutionary Model For Submillimeter Galaxies (2006)
Chakrabarti, Sukanya, Fenner, Yeshe, Hernquist, Lars, Cox, T. J., Hopkins, Philip F.
[abridged]We calculate multi-wavelength spectral energy distributions (SEDs) (spanning optical to millimeter wavelengths) from simulations of major galaxy mergers with black hole feedback which...
Early Cosmological HII/HeIII Regions and Their Impact on Second-Generation Star Formation (2006)
Yoshida, Naoki, Oh, S. Peng, Kitayama, Tetsu, Hernquist, Lars
(Abridged) We present the results of three-dimensional radiation-hydrodynamics simulations of the formation and evolution of early HII/HeIII regions around the first stars. Cooling (by H2 and HD) and...
The morphology of HII regions during reionization (2006)
McQuinn, Matthew, Lidz, Adam, Zahn, Oliver, Dutta, Suvendra, Hernquist, Lars, Zaldarriaga, Matias
It is possible that the properties of HII regions during reionization depend sensitively on many poorly constrained quantities (the nature of the ionizing sources, the clumpiness of the gas in the...
Higher Order Contributions to the 21 cm Power Spectrum (2006)
Lidz, Adam, Zahn, Oliver, McQuinn, Matthew, Zaldarriaga, Matias, Dutta, Suvendra, Hernquist, Lars
We consider the contribution of 3rd and 4th order terms to the power spectrum of 21 cm brightness temperature fluctuations during the epoch of reionization, which arise because the 21 cm brightness...
Formation of z ~ 6 quasars from hierarchical galaxy mergers (2006)
Li, Yuexing, Hernquist, Lars, Robertson, Brant, Cox, Thomas J., Hopkins, Philip F., Springel, Volker, ...
The discovery of luminous quasars at redshift z ~ 6 indicates the presence of supermassive black holes (SMBHs) of mass ~10^9 Msun when the Universe was less than one billion years old. This finding...
Hopkins, Philip F., Robertson, Brant, Krause, Elisabeth, Hernquist, Lars, Cox, Thomas J.
We describe a model-independent integral constraint which defines an upper limit to the allowed degree of evolution in the ratio of black hole (BH) mass to host galaxy luminosity or mass, as a...
Kinematic Structure of Merger Remnants (2006)
Cox, T. J., Dutta, Suvendra N., Di Matteo, Tiziana, Hernquist, Lars, Hopkins, Philip F., Robertson, Brant, ...
We use numerical simulations to study the kinematic structure of remnants formed from mergers of equal-mass disk galaxies. In particular, we show that remnants of dissipational mergers, which include...
Formation of Primordial Stars in a LCDM Universe (2006)
Yoshida, Naoki, Omukai, Kazuyuki, Hernquist, Lars, Abel, Tom
We study the formation of the first generation of stars in the standard cold dark matter model, using a very high-resolution hydordynamic simulations. Our simulation achieves a dynamic range of...
An Observational Determination of the Bolometric Quasar Luminosity Function (2006)
Hopkins, Philip F., Richards, Gordon T., Hernquist, Lars
We combine a large set of quasar luminosity function (QLF) measurements from the rest-frame optical, soft and hard X-ray, and near- and mid-infrared bands to determine the bolometric QLF in the...
Chakrabarti, Sukanya, Cox, T. J., Hernquist, Lars, Hopkins, Philip F., Robertson, Brant, Di Matteo, Tiziana
We calculate infrared spectral energy distributions (SEDs) from simulations of major galaxy mergers and study the effect of AGN and starburst driven feedback on the evolution of the SED as a function...
Simulations and Analytic Calculations of Bubble Growth During Hydrogen Reionization (2006)
Zahn, Oliver, Lidz, Adam, McQuinn, Matthew, Dutta, Suvendra, Hernquist, Lars, Zaldarriaga, Matias, ...
We present results from a large volume simulation of Hydrogen reionization. We combine 3d radiative transfer calculations and an N-body simulation, describing structure formation in the intergalactic...
Molecular Outflows in Galaxy Merger Simulations with Embedded AGN (2006)
Narayanan, Desika, Cox, Thomas J., Robertson, Brant, Dave, Romeel, Di Matteo, Tiziana, Hernquist, Lars, ...
We study the effects of feedback from active galactic nuclei (AGN) on emission from molecular gas in galaxy mergers by combining hydrodynamic simulations which include black holes with a...
Simulated Molecular Gas Emission in Galaxy Mergers with Embedded AGN (2006)
Narayanan, Desika, Cox, Thomas J., Robertson, Brant, Dave, Romeel, Di Matteo, Tiziana, Hernquist, Lars, ...
We investigate the effect of embedded active galactic nuclei (AGN) in galaxy mergers on the CO molecular line emission by combining non-local thermodynamic equilibrium (LTE) radiative transfer...
Fueling Low-Level AGN Activity Through the Stochastic Accretion of Cold Gas (2006)
Hopkins, Philip F., Hernquist, Lars
Using a simple description of feedback from black hole (BH) growth, we develop an analytic model for the fueling of Seyferts (low-luminosity AGN) and their relation to their host galaxies, Eddington...
Nagamine, Kentaro, Cen, Renyue, Furlanetto, Steven R., Hernquist, Lars, Night, Christopher, Ostriker, Jeremiah P.
Cosmological hydrodynamic simulations have significantly improved over the past several years, and we have already shown that the observed properties of Lyman-break galaxies (LBGs) at z=3 can be...
Hopkins, Philip F., Somerville, Rachel S., Hernquist, Lars, Cox, Thomas J., Robertson, Brant, Li, Yuexing
Using a model for self-regulated growth of black holes (BHs) in mergers involving gas-rich galaxies, we study the relationship between quasars and the population of merging galaxies and predict the...
Hopkins, Philip F., Bundy, Kevin, Hernquist, Lars, Ellis, Richard S.
We compile a number of observations to estimate the time-averaged rate of formation or buildup of red sequence galaxies, as a function of mass and redshift. Comparing this with the mass functions of...
Nagamine, Kentaro, Wolfe, Arthur M., Hernquist, Lars
We discuss the detectability of high-redshift galaxies via [CII] 158 micron line emission by coupling an analytic model with cosmological Smoothed Particle Hydrodynamics (SPH) simulations that are...
The evolution in the faint-end slope of the quasar luminosity function (2006)
Hopkins, Philip F., Hernquist, Lars, Cox, Thomas J., Robertson, Brant, Di Matteo, Tiziana, Springel, Volker
Hopkins, Philip F., Hernquist, Lars, Cox, Thomas J., Di Matteo, Tiziana, Robertson, Brant, Springel, Volker
Determining the properties and evolution of red galaxies from the quasar luminosity function (2006)
Hopkins, Philip F., Hernquist, Lars, Cox, Thomas J., Robertson, Brant, Springel, Volker
The evolution of the MBH-σ relation (2006)
Robertson, Brant, Hernquist, Lars, Cox, Thomas J., Di Matteo, Tiziana, Hopkins, Philip F., Martini, Paul, ...
The fundamental scaling relations of elliptical galaxies (2006)
Robertson, Brant, Cox, Thomas J., Hernquist, Lars, Franx, Marijn, Hopkins, Philip F., Martini, Paul, ...
X-Ray emission from hot gas in galaxy mergers (2006)
Cox, T. J., Di Matteo, Tiziana, Hernquist, Lars, Hopkins, Philip F., Robertson, Brant, Springel, Volker
A merger-driven scenario for cosmological disk galaxy formation (2006)
Robertson, Brant, Bullock, James S., Cox, Thomas J., Di Matteo, Tiziana, Hernquist, Lars, Springel, Volker, ...
The kinematic structure of merger remnants (2006)
Cox, T. J., Dutta, Suvendra N., Di Matteo, Tiziana, Hernquist, Lars, Hopkins, Philip F., Robertson, Brant, ...
Hopkins, Philip F., Somerville, Rachel S., Hernquist, Lars, Cox, Thomas J., Robertson, Brant, Li, Yuexing
Using a model for the self-regulated growth of supermassive BHs in mergers involving gas-rich galaxies, we study the relationship between quasars and the population of merging galaxies and predict...
Croft, Rupert A. C., Banday, A. J., Hernquist, Lars
The intergalactic neutral hydrogen which is responsible for the Lyman alpha forest of quasar absorption is a tracer of much larger amounts of ionised hydrogen. The ionised component has yet to be...
Cosmological Parameter Estimation Using 21 cm Radiation from the Epoch of Reionization (2005)
McQuinn, Matthew, Zahn, Oliver, Zaldarriaga, Matias, Hernquist, Lars, Furlanetto, Steven R.
A number of radio interferometers are currently being planned or constructed to observe 21 cm emission from reionization. Not only will such measurements provide a detailed view of that epoch, but,...
The Impact of Temperature Fluctuations on the Lyman-alpha Forest Power Spectrum (2005)
Lai, Kamson, Lidz, Adam, Hernquist, Lars, Zaldarriaga, Matias
We explore the impact of spatial fluctuations in the intergalactic medium temperature on the Lyman-alpha forest flux power spectrum near z ~ 3. We develop a semianalytic model to examine temperature...
Distribution of Damped Lyman-alpha Absorbers in a Lambda Cold Dark Matter Universe (2005)
Nagamine, Kentaro, Wolfe, Arthur M., Hernquist, Lars, Springel, Volker
We present the results of a numerical study of a galactic wind model and its implications on the properties of damped Lyman-alpha absorbers (DLAs) using cosmological hydrodynamic simulations. We vary...
Building Galaxies with Simulations (2005)
Davé, Romeel, Finlator, Kristian, Hernquist, Lars, Katz, Neal, Kereš, Dušan, Papovich, Casey, ...
We present an overview of some of the issues surrounding current models of galaxy formation, highlighting recent insights obtained from cosmological hydrodynamic simulations. Detailed examination of...
How Much Mass do Supermassive Black Holes Eat in their Old Age? (2005)
Hopkins, Philip F., Narayan, Ramesh, Hernquist, Lars
We consider the distribution of local supermassive black hole Eddington ratios and accretion rates, accounting for the dependence of radiative efficiency and bolometric corrections on the accretion...
The Evolution in the Faint-End Slope of the Quasar Luminosity Function (2005)
Hopkins, Philip F., Hernquist, Lars, Cox, Thomas J., Di Matteo, Tiziana, Robertson, Brant, Springel, Volker
(Abridged) Based on numerical simulations of galaxy mergers that incorporate black hole (BH) growth, we predict the faint end slope of the quasar luminosity function (QLF) and its evolution with...
Determining the Properties and Evolution of Red Galaxies from the Quasar Luminosity Function (2005)
Hopkins, Philip F., Hernquist, Lars, Cox, Thomas J., Robertson, Brant, Springel, Volker
(Abridged) We study the link between quasars and the red galaxy population using a model for the self-regulated growth of supermassive black holes in mergers involving gas-rich galaxies. Using a...
Characteristic Scales During Reionization (2005)
Furlanetto, Steven R., McQuinn, Matthew, Hernquist, Lars
One of the key observables of the reionization era is the distribution of neutral and ionized gas. Recently, Furlanetto, Zaldarriaga, & Hernquist developed a simple analytic model to describe the...
The Luminosity Dependence of Quasar Clustering (2005)
Lidz, Adam, Hopkins, Philip F., Cox, Thomas J., Hernquist, Lars, Robertson, Brant
We investigate the luminosity dependence of quasar clustering, inspired by numerical simulations of galaxy mergers that incorporate black hole growth. These simulations have motivated a new...
The Effects of Reionization on Lyman-alpha Galaxy Surveys (2005)
Furlanetto, Steven R., Zaldarriaga, Matias, Hernquist, Lars
Searches for Lyman-alpha emission lines are among the most effective ways to identify high-redshift galaxies. They are particularly interesting because they probe not only the galaxies themselves but...
Hopkins, Philip F., Hernquist, Lars, Cox, Thomas J., Di Matteo, Tiziana, Robertson, Brant, Springel, Volker
We present an evolutionary model for starbursts, quasars, and spheroidal galaxies in which mergers between gas-rich galaxies drive nuclear inflows of gas, producing intense starbursts and feeding the...
The Evolution of the M-sigma Relation (2005)
Robertson, Brant, Hernquist, Lars, Cox, Thomas J., Di Matteo, Tiziana, Hopkins, Philip F., Martini, Paul, ...
(Abridged) We examine the evolution of the black hole mass - stellar velocity dispersion (M-sigma) relation over cosmic time using simulations of galaxy mergers that include feedback from...
Luminosity-Dependent Quasar Lifetimes: A New Interpretation of the Quasar Luminosity Function (2005)
Hopkins, Philip F., Hernquist, Lars, Cox, Thomas J., Di Matteo, Tiziana, Robertson, Brant, Springel, Volker
We propose a new interpretation of the quasar luminosity function (LF), derived from physically motivated models of quasar lifetimes and light curves. In our picture, quasars evolve rapidly and their...
Hopkins, Philip F., Hernquist, Lars, Cox, Thomas J., Di Matteo, Tiziana, Robertson, Brant, Springel, Volker
We consider implications of our new model of quasar lifetimes and light curves for the quasar luminosity function (LF) at different frequencies and redshifts. In our picture, quasars evolve rapidly...
The Kinetic Sunyaev-Zel'dovich Effect from Reionization (2005)
McQuinn, Matthew, Furlanetto, Steven R., Hernquist, Lars, Zahn, Oliver, Zaldarriaga, Matias
During the epoch of reionization, local variations in the ionized fraction (patchiness) imprint arcminute-scale temperature anisotropies in the CMB through the kinetic Sunyaev-Zel'dovich (kSZ)...
Black Holes in Galaxy Mergers: Evolution of Quasars (2005)
Hopkins, Philip F., Hernquist, Lars, Cox, Thomas J., Di Matteo, Tiziana, Martini, Paul, Robertson, Brant, ...
Based on numerical simulations of gas-rich galaxy mergers, we discuss a model in which quasar activity is tied to the self-regulated growth of supermassive black holes in galaxies. Nuclear inflow of...
X-ray Emission from Hot Gas in Galaxy Mergers (2005)
Cox, T. J., Di Matteo, Tiziana, Hernquist, Lars, Hopkins, Philip F., Robertson, Brant, Springel, Volker
We examine X-ray emission produced from hot gas during collisions and mergers of disk galaxies. To study this process, we employ simulations that incorporate cosmologically motivated disk-galaxy...
Lyman Break Galaxies at z = 4 - 6 in cosmological SPH Simulations (2005)
Night, Christopher, Nagamine, Kentaro, Springel, Volker, Hernquist, Lars
We perform a spectrophotometric analysis of galaxies at redshifts z = 4 - 6 in cosmological SPH simulations of a Lambda CDM universe. Our models include radiative cooling and heating by a uniform UV...
A Merger-Driven Scenario for Cosmological Disk Galaxy Formation (2005)
Robertson, Brant, Bullock, James S., Cox, Thomas J., Di Matteo, Tiziana, Hernquist, Lars, Springel, Volker, ...
(Abridged) The violent hierarchical nature of the LCDM cosmology poses serious difficulties for the formation of disk galaxies. To help resolve these issues, we describe a new, merger-driven scenario...
The influence of non-uniform reionization on the CMB (2005)
Zahn, Oliver, Zaldarriaga, Matias, Hernquist, Lars, McQuinn, Matthew
We investigate the impact of spatial variations in the ionized fraction during reionization on temperature anisotropies in the CMB. We combine simulations of large scale structure to describe the...
A QED Model for Non-thermal Emission from SGRs and AXPs (2005)
Heyl, Jeremy S., Hernquist, Lars
Previously, we showed that, owing to effects arising from quantum electrodynamics (QED), magnetohydrodynamic fast modes of sufficient strength will break down to form electron-positron pairs while...
A Physical Model for the Origin of Quasar Lifetimes (2005)
Hopkins, Philip F., Hernquist, Lars, Martini, Paul, Cox, Thomas J., Robertson, Brant, Di Matteo, Tiziana, ...
We propose a model of quasar lifetimes in which observational quasar lifetimes and an intrinsic lifetime of rapid accretion are strongly distinguished by the physics of obscuration by surrounding gas...
Di Matteo, Tiziana, Springel, Volker, Hernquist, Lars
In the early Universe, while galaxies were still forming, black holes as massive as a billion solar masses powered quasars. Supermassive black holes are found at the centers of most galaxies today,...
Lambda-Cold Dark Matter, Stellar Feedback, and the Galactic Halo Abundance Pattern (2005)
Robertson, Brant, Bullock, James S., Font, Andreea S., Johnston, Kathryn V., Hernquist, Lars
(Abridged) The hierarchical formation scenario for the stellar halo requires the accretion and disruption of dwarf galaxies, yet low-metallicity halo stars are enriched in alpha-elements compared to...
Lyα emission from structure formation (2005)
Furlanetto, Steven R., Schaye, Joop, Springel, Volker, Hernquist, Lars
Confronting cosmological simulations with observations of intergalactic metals (2005)
Aguirre, Anthony, Schaye, Joop, Hernquist, Lars, Kay, Scott, Springel, Volker, Theuns, Tom
Massive galaxies in cosmological simulations: ultraviolet-selected sample at redshift z=2 (2005)
Nagamine, Kentaro, Cen, Renyue, Hernquist, Lars, Ostriker, Jeremiah P., Springel, Volker
A physical model for the origin of quasar lifetimes (2005)
Hopkins, Philip F., Hernquist, Lars, Martini, Paul, Cox, Thomas J., Robertson, Brant, Di Matteo, Tiziana, ...
Massive galaxies at Z = 2 in cosmological hydrodynamic simulations (2005)
Nagamine, Kentaro, Cen, Renyue, Hernquist, Lars, Ostriker, Jeremiah P., Springel, Volker
Comparing AMR and SPH cosmological simulations - I. Dark matter and adiabatic simulations (2005)
O'Shea, Brian W., Nagamine, Kentaro, Springel, Volker, Hernquist, Lars, Norman, Michael L.
Black holes in galaxy mergers: evolution of quasars (2005)
Hopkins, Philip F., Hernquist, Lars, Cox, Thomas J., Di Matteo, Tiziana, Martini, Paul, Robertson, Brant, ...
Luminosity-dependent quasar lifetimes: a new interpretation of the quasar luminosity function (2005)
Hopkins, Philip F., Hernquist, Lars, Cox, Thomas J., Di Matteo, Tiziana, Robertson, Brant, Springel, Volker
Hopkins, Philip F., Hernquist, Lars, Cox, Thomas J., Di Matteo, Tiziana, Robertson, Brant, Springel, Volker
Formation of a spiral galaxy in a major merger (2004)
Springel, Volker, Hernquist, Lars
We use numerical simulations to examine the structure of merger remnants resulting from collisions of gas-rich spiral galaxies. When the gas fraction of the progenitors is small, the remnants...
Massive galaxies at redshift 2 in cosmological hydrodynamic simulations (2004)
Nagamine, Kentaro, Cen, Renyue, Hernquist, Lars, Ostriker, Jeremiah P., Springel, Volker
We study the properties of galaxies at z=2 in a Lambda cold dark matter universe, using two different types of hydrodynamic simulation methods -- Eulerian TVD and smoothed particle hydrodynamics...
Modeling feedback from stars and black holes in galaxy mergers (2004)
Springel, Volker, Di Matteo, Tiziana, Hernquist, Lars
We describe techniques for incorporating feedback from star formation and black hole accretion into simulations of isolated and merging galaxies. At present, the details of these processes cannot be...
Confronting cosmological simulations with observations of intergalactic metals (2004)
Aguirre, Anthony, Schaye, Joop, Hernquist, Lars, Kay, Scott, Springel, Volker, Theuns, Tom
Using the statistics of pixel optical depths, we compare HI, CIV and CIII absorption in a set of six high quality z ~ 3-4 quasar absorption spectra to that in spectra drawn from two different...
The Temperature Structure of the Warm-Hot Intergalactic Medium (2004)
Yoshida, Naoki, Furlanetto, Steven, Hernquist, Lars
We study the temperature structure of the intergalactic medium (IGM) using a large cosmological N-body/SPH simulation. We employ a two-temperature model for the thermal evolution of the ionized gas,...
Lyman-alpha Emission from Structure Formation (2004)
Furlanetto, Steven, Schaye, Joop, Springel, Volker, Hernquist, Lars
The nature of the interaction between galaxies and the intergalactic medium (IGM) is one of the most fundamental problems in astrophysics. The accretion of gas onto galaxies provides fuel for star...
Black holes in galaxy mergers: The formation of red elliptical galaxies (2004)
Springel, Volker, Di Matteo, Tiziana, Hernquist, Lars
We use hydrodynamical simulations to study the color transformations induced by star formation and active galactic nuclei (AGN) during major mergers of spiral galaxies. Our modeling accounts for...
Schaefer, Bjoern Malte, Pfrommer, Christoph, Bartelmann, Matthias, Springel, Volker, Hernquist, Lars
All-sky thermal and kinetic Sunyaev-Zel'dovich (SZ) maps are presented for assessing how well the PLANCK-mission can find and characterise clusters of galaxies, especially in the presence of primary...
Constraining the Topology of Reionization Through Lyman-alpha Absorption (2004)
Furlanetto, Steven, Hernquist, Lars, Zaldarriaga, Matias
The reionization of hydrogen in the intergalactic medium (IGM) is a crucial landmark in the history of the universe, but the processes through which it occurs remain mysterious. In particular, recent...
Massive galaxies in cosmological simulations: UV-selected sample at redshift z=2 (2004)
Nagamine, Kentaro, Cen, Renyue, Hernquist, Lars, Ostriker, Jeremiah P., Springel, Volker
We study the properties of galaxies at z=2 in a Lambda CDM universe, using two different types of hydrodynamic simulation methods (Eulerian TVD and SPH) and a spectrophotometric analysis in the Un,...
Statistical Probes of Reionization With 21 cm Tomography (2004)
Furlanetto, Steven, Zaldarriaga, Matias, Hernquist, Lars
We consider the degree to which "21 cm tomography" of the high-redshift Universe can distinguish different ionization histories. Using a new analytic model for the size distribution of HII regions...
The Growth of HII Regions During Reionization (2004)
Furlanetto, Steven, Zaldarriaga, Matias, Hernquist, Lars
Recently, there has been a great deal of interest in understanding the reionization of hydrogen in the intergalactic medium (IGM). One of the major outstanding questions is how this event proceeds on...
Was the Universe Reionized at Redshift 10? (2004)
Loeb, Abraham, Barkana, Rennan, Hernquist, Lars
Recently, Pello et al. (2004) claimed to have discovered a galaxy at a redshift z=10, and identified a feature in its spectrum with a hydrogen Lyman-alpha emission line. If this identification is...
Gerssen, Joris, Van Der Marel, Roeland, Axon, David, Mihos, Christopher, Hernquist, Lars, Barnes, Joshua
Also archived in: arXiv:astro-ph/0310029 v1 1 Oct 2003
Gerssen, Joris, Van Der Marel, Roeland, Axon, David, Mihos, Christopher, Hernquist, Lars, Barnes, Joshua
Also archived in: arXiv:astro-ph/0310029 v1 1 Oct 2003
Is there a missing galaxy problem at high redshift? (2004)
Nagamine, Kentaro, Cen, Renyue, Hernquist, Lars, Ostriker, Jeremiah P., Springel, Volker
The cosmological evolution of metal enrichment in quasar host galaxies (2004)
Di Matteo, Tiziana, Croft, Rupert A. C., Springel, Volker, Hernquist, Lars
Cosmic reionization by stellar sources: population III stars (2004)
Sokasian, Aaron, Yoshida, Naoki, Abel, Tom, Hernquist, Lars, Springel, Volker
Ultraviolet line emission from metals in the low-redshift intergalactic medium (2004)
Furlanetto, Steven R., Schaye, Joop, Springel, Volker, Hernquist, Lars
Disk galaxy formation in a cold dark matter universe (2004)
Robertson, Brant, Yoshida, Naoki, Springel, Volker, Hernquist, Lars
Searching for star formation beyond reionization (2004)
Davé, Romeel, Smith, John-David T., Papovich, Casey, Hernquist, Lars, Springel, Volker
Comparing AMR and SPH Cosmological Simulations: I. Dark Matter & Adiabatic Simulations (2003)
O'Shea, Brian W., Nagamine, Kentaro, Springel, Volker, Hernquist, Lars, Norman, Michael L.
We compare two cosmological hydrodynamic simulation codes in the context of hierarchical galaxy formation: The SPH code GADGET, and the Eulerian AMR code ENZO. Both codes represent dark matter with...
A QED Model for the Origin of Bursts from SGRs and AXPs (2003)
Heyl, Jeremy S., Hernquist, Lars
We propose a model to account for the bursts from soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) in which quantum electrodynamics (QED) plays a vital role. In our theory, that we term...
21 Centimeter Fluctuations from Cosmic Gas at High Redshifts (2003)
Zaldarriaga, Matias, Furlanetto, Steven, Hernquist, Lars
The relatively large Thomson optical depth, tau_e, inferred recently from the WMAP observations suggests that the Universe was reionized in a more complex manner than previously believed. However,...
Is There a Missing Galaxy Problem at High Redshift? (2003)
Nagamine, Kentaro, Cen, Renyue, Hernquist, Lars, Ostriker, Jeremiah P., Springel, Volker
We study the evolution of the global stellar mass density in a Lambda cold dark matter universe using two different types of hydrodynamical simulations (Eulerian TVD and SPH) and the analytical model...
Photometric Properties of Lyman-break Galaxies at z=3 in Cosmological SPH Simulations (2003)
Nagamine, Kentaro, Springel, Volker, Hernquist, Lars, Machacek, Marie
We study the photometric properties of Lyman-break galaxies (LBGs) formed by redshift z=3 in a set of large cosmological smoothed-particle hydrodynamics simulations of the Lambda cold dark matter...
Mapping the Cosmic Web with Ly-alpha Emission (2003)
Furlanetto, Steven, Schaye, Joop, Springel, Volker, Hernquist, Lars
We use a high-resolution cosmological simulation to predict the distribution of HI Ly-alpha emission from the low-redshift (z10^2 kpc) ``coronae'' of optically thin gas with Ly-alpha surface...
Damped Lyman-alpha Absorbers in Cosmological SPH Simulations: the "metallicity problem" (2003)
Nagamine, Kentaro, Springel, Volker, Hernquist, Lars
We study the distribution of star formation rate (SFR) and metallicity of damped Lyman-alpha absorbers (DLAs) using cosmological smoothed particle hydrodynamics (SPH) simulations of the Lambda cold...
Searching for Star Formation Beyond Reionization (2003)
Barton, Elizabeth J., Dav'e, Romeel, Smith, John-David T., Papovich, Casey, Hernquist, Lars, Springel, Volker
The goal of searching back in cosmic time to find star formation during the epoch of reionization will soon be within reach. We assess the detectability of high-redshift galaxies by combining...
The Era of Massive Population III Stars: Cosmological Implications and Self-Termination (2003)
Yoshida, Naoki, Bromm, Volker, Hernquist, Lars
The birth and death of the first generation of stars have important implications for the thermal state and chemical properties of the intergalactic medium (IGM) in the early universe. Sometime after...
Gerssen, Joris, Van Der Marel, Roeland P., Axon, David, Mihos, J. Christopher, Hernquist, Lars, Barnes, Joshua E.
We present results from an HST study of the morphology and kinematics of NGC 6240. This merging galaxy with a double nucleus is one of the nearest and best-studied ultraluminous infrared galaxies....
Ultraviolet Line Emission from Metals in the Low-Redshift Intergalactic Medium (2003)
Furlanetto, Steven, Schaye, Joop, Springel, Volker, Hernquist, Lars
We use a high-resolution cosmological simulation that includes hydrodynamics, multiphase star formation, and galactic winds to predict the distribution of metal line emission at z~0 from the...
The cosmological evolution of metal enrichment in quasar host galaxies (2003)
Di Matteo, Tiziana, Croft, Rupert A. C., Springel, Volker, Hernquist, Lars
We study the gas metallicity of quasar hosts using cosmological hydrodynamic simulations of the Lambda-cold dark matter model. Galaxy formation in the simulations is coupled with a prescription for...
The Angular Momentum of Gas in Proto-Galaxies: II -- The Impact of Preheating (2003)
We examine the effect of preheating of the intergalactic medium on galaxy formation using cosmological hydrodynamical simulations. By performing simulations both with and without a simple model for...
Cosmic Reionisation by Stellar Sources: Population III Stars (2003)
Sokasian, Aaron, Yoshida, Naoki, Abel, Tom, Hernquist, Lars, Springel, Volker
We combine fast radiative transfer calculations with high resolution hydrodynamical simulations to study an epoch of early hydrogen reionisation by primordial stellar sources at redshifts 15
Yoshida, Naoki, Sokasian, Aaron, Hernquist, Lars, Springel, Volker
(abridged) We study high redshift structure formation and reionization in a LCDM universe under the assumption that the spectral power index of primordial density fluctuations is a function of length...
Nagamine, Kentaro, Springel, Volker, Hernquist, Lars
We study the distribution of the star formation rate and metallicity of damped Lyman-alpha absorbers using cosmological SPH simulations of the Lambda cold dark matter model in the redshift range...
The First Supernova Explosions in the Universe (2003)
Bromm, Volker, Yoshida, Naoki, Hernquist, Lars
We investigate the supernova explosions that end the lives of massive Population III stars in low-mass minihalos (M~10^6 M_sun) at redshifts z~20. Employing the smoothed particle hydrodynamics...
The Evolution of Baryon Density Fluctuations in Multi-Component Cosmological Simulations (2003)
Yoshida, Naoki, Sugiyama, Naoshi, Hernquist, Lars
We critically examine how the evolution of the matter density field in cosmological simulations is affected by details of setting up initial conditions. We show that it is non-trivial to realise an...
Observing the Reionization Epoch Through 21 Centimeter Radiation (2003)
Furlanetto, Steven, Sokasian, Aaron, Hernquist, Lars
We study the observability of the reionization epoch through the 21 cm hyperfine transition of neutral hydrogen. We use a high-resolution cosmological simulation (including hydrodynamics) together...
Early Structure Formation and Reionization in a Warm Dark Matter Cosmology (2003)
Yoshida, Naoki, Sokasian, Aaron, Hernquist, Lars, Springel, Volker
We study first structure formation in Lambda-dominated universes using large cosmological N-body/SPH simulations. We consider a standard LCDM model and a LWDM model in which the mass of the dark...
Cosmic Reionisation by Stellar Sources: Population II Stars (2003)
Sokasian, Aaron, Abel, Tom, Hernquist, Lars, Springel, Volker
We study the reionisation of the Universe by stellar sources using a numerical approach that combines fast 3D radiative transfer calculations with high resolution hydrodynamical simulations. Ionising...
Effects of Wandering on the Coalescence of Black Hole Binaries in Galactic Centers (2003)
Chatterjee, Pinaki, Hernquist, Lars, Loeb, Abraham
We examine whether massive binary black holes in spherically symmetric bulges of galaxies can achieve coalescence through the emission of gravitational radiation under the action of stellar dynamical...
Abundance of damped Lyman-alpha absorbers in cosmological SPH simulations (2003)
Nagamine, Kentaro, Springel, Volker, Hernquist, Lars
We use cosmological smoothed-particle hydrodynamics (SPH) simulations of the Lambda cold dark matter (CDM) model to study the abundance of damped Lyman-alpha absorbers (DLAs) in the redshift range...
Simulations of Early Structure Formation: Primordial Gas Clouds (2003)
Yoshida, Naoki, Abel, Tom, Hernquist, Lars, Sugiyama, Naoshi
(abridged) We use large cosmological simulations to study the origin of primordial star-forming clouds in a Lambda CDM universe, by following the formation of dark matter halos and the cooling of gas...
Black hole growth and activity in a LambdaCDM Universe (2003)
Di Matteo, Tiziana, Croft, Rupert A. C., Springel, Volker, Hernquist, Lars
(abridged) The observed properties of supermassive black holes suggest a fundamental link between their assembly and the formation of their host spheroids. We model the growth and activity of black...
Springel, Volker, Hernquist, Lars
We present a model for star formation and supernova feedback that describes the multiphase structure of star-forming gas on scales that are typically not resolved in cosmological simulations. Our...
The history of star formation in a Lambda cold dark matter universe (2003)
Springel, Volker, Hernquist, Lars
Employing hydrodynamic simulations of structure formation in a Lambda cold dark matter cosmology, we study the history of cosmic star formation from the 'dark ages' at redshift z similar to 20 to the...
Gamma Rays from Intergalactic Shocks (2003)
Keshet, Uri, Waxman, Eli, Loeb, Abraham, Springel, Volker, Hernquist, Lars
Mapping the cosmic web with Ly α emission (2003)
Furlanetto, Steven R., Schaye, Jopp, Springel, Volker, Hernquist, Lars
Galaxy Clustering and Galaxy Bias in a Lambda-CDM Universe (2002)
Weinberg, David H., Dav'e, Romeel, Katz, Neal, Hernquist, Lars
We investigate galaxy clustering and galaxy-mass correlations in the LCDM cosmological model using a large volume SPH simulation. For the most part, the predicted biases between galaxies and dark...
An analytical model for the history of cosmic star formation (2002)
Hernquist, Lars, Springel, Volker
We use simple analytic reasoning to identify physical processes that drive the evolution of the cosmic star formation density in cold dark matter universes. Based on our analysis, we formulate a...
Three Epochs of Star Formation in the High Redshift Universe (2002)
Mackey, Jonathan, Bromm, Volker, Hernquist, Lars
We investigate the impact of an early population of massive stars on their surroundings. Dissociation of molecular hydrogen by strong UV emission from such stars is expected to produce a global...
Cosmological SPH simulations: A hybrid multi-phase model for star formation (2002)
Springel, Volker, Hernquist, Lars
We present a model for star formation and supernova feedback that describes the multi-phase structure of star forming gas on scales that are typically not resolved in cosmological simulations. Our...
The history of star formation in a LCDM universe (2002)
Springel, Volker, Hernquist, Lars
Employing hydrodynamic simulations of structure formation in a LCDM cosmology, we study the history of cosmic star formation from the "dark ages" at redshift z~20 to the present. In addition to...
White, Martin, Hernquist, Lars, Springel, Volker
We present results on the thermal and kinetic Sunyaev-Zel'dovich (SZ) effects from a sequence of high resolution hydrodynamic simulations of structure formation, including cooling, feedback and metal...
High redshift galaxies and the Lyman-alpha forest in a CDM universe (2002)
Croft, Rupert A. C., Hernquist, Lars, Springel, Volker, Westover, Michael, White, Martin
We use a cosmological hydrodynamic simulation of a cold dark matter universe to investigate theoretically the relationship between high redshift galaxies and the Lyman=alpha forest at redshift z=3....
Gamma-Rays from Intergalactic Shocks (2002)
Keshet, Uri, Waxman, Eli, Loeb, Abraham, Springel, Volker, Hernquist, Lars
Structure formation in the intergalactic medium (IGM) produces large-scale, collisionless shock waves, where electrons can accelerate to highly relativistic energies. Such electrons can Compton...
Brownian Motion in Gravitationally-Interacting Systems (2002)
Chatterjee, Pinaki, Hernquist, Lars, Loeb, Abraham
We derive a model that describes the motion of a Brownian particle in a system which is dominated by gravitational forces. An example of such a system is a massive black hole immersed in a cluster of...
Abel, Tom, Croft, Rupert A. C., Hernquist, Lars, White, Simon D. M.
We use non-radiative N-body/SPH simulations of structure formation in a LCDM cosmology to compare the angular momentum distributions of dark matter and gas in a large sample of halos. We show that...
Hydrogen-Poor Disks in Compact X-Ray Binaries (2001)
Menou, Kristen, Perna, Rosalba, Hernquist, Lars
We show that accretion disks in several compact X-ray binaries with hydrogen-depleted donors are likely subject to a thermal ionization instability, unless they are strongly irradiated. These disks...
On the "initial" Angular Momentum of Galaxies (2001)
Abel, Tom, Croft, Rupert C., Hernquist, Lars
Spherical density profiles and specific angular momentum profiles of Dark Matter halos found in cosmological N-body simulations have been measured extensively. The distribution of the total angular...
Cosmological SPH simulations: The entropy equation (2001)
Springel, Volker, Hernquist, Lars
We discuss differences in simulation results that arise between the use of either the thermal energy or the entropy as an independent variable in smoothed particle hydrodynamics (SPH). In this...
The Evolution of Cuspy Triaxial Galaxies Harboring Central Black Holes (2001)
Holley-Bockelmann, Kelly, Mihos, J. Christopher, Sigurdsson, Steinn, Hernquist, Lars, Norman, Colin
We use numerical simulations to study the evolution of triaxial elliptical galaxies with central black holes. In contrast to earlier numerical studies which used galaxy models with central density...
Group Scaling Relations From a Cosmological Hydrodynamic Simulation: No Pre-heating Required? (2001)
Davé, Romeel, Katz, Neal, Hernquist, Lars, Weinberg, David
We investigate the X-ray vs. optical scaling relations of poor groups to small clusters (sigma~100-700 km/s) identified in a cosmological hydrodynamic simulation of a Lambda-CDM universe, with...
Dynamics of a Massive Black Hole at the Center of a Dense Stellar System (2001)
Chatterjee, Pinaki, Hernquist, Lars, Loeb, Abraham
We develop a simple physical model to describe the dynamics of a massive point-like object, such as a black hole, near the center of a dense stellar system. It is shown that the total force on this...
Sub-mm Galaxies in Cosmological Simulations (2001)
Fardal, Mark A., Katz, Neal, Weinberg, David H., Davé, Romeel, Hernquist, Lars
We study the predicted sub-mm emission from massive galaxies in a Lambda-CDM universe, using hydrodynamic cosmological simulations. Assuming that most of the emission from newly formed stars is...
The Infuence of Omega_baryon on High-Redshift Structure (2001)
Gardner, Jeffrey P., Katz, Neal, Hernquist, Lars, Weinberg, David H.
We analyze high-redshift structure in three hydrodynamic simulations that have identical initial conditions and cosmological parameters and differ only in the value of the baryon density parameter,...
The distribution of mass around galaxies (2001)
White, Martin, Hernquist, Lars, Springel, Volker
We explore the distribution of mass about the expected sites of galaxy formation in a high-resolution hydrodynamical simulation of a LCDM cosmology which includes cooling, star-formation and...
The growth of galaxies in cosmological simulations of structure formation (2001)
Murali, Chigurupati, Katz, Neal, Hernquist, Lars, Weinberg, David H., Dave, Romeel
We use hydrodynamic simulations to examine how the baryonic components of galaxies are assembled, focusing on the relative importance of mergers and smooth accretion in the formation of ~L_* systems....
Metal Enrichment of the Intergalactic Medium in Cosmological Simulations (2001)
Aguirre, Anthony, Hernquist, Lars, Schaye, Joop, Katz, Neal, Weinberg, David H., Gardner, Jeffrey
Observations have established that the diffuse intergalactic medium (IGM) at z ~ 3 is enriched to ~0.1-1% solar metallicity and that the hot gas in large clusters of galaxies (ICM) is enriched to...
HST [Hubble Space Telescope] observations of NGC 6240 (2001)
Gerssen, Joris, Van Der Marel, Roeland, Axon, David, Mihos, Christopher, Hernquist, Lars, Barnes, Joshua
"The Central kiloparsec of Starbursts and AGN: La Palma Connection". Proceedings of the Astronomical Society of the Pacific Conference Series. Astronomical Society of the Pacific. Held at Hotel...
X-ray emission from middle-aged pulsars (2001)
Perna, Rosalba, Heyl, Jeremy, Hernquist, Lars
We present a simple, unified model which accounts for properties of the X-ray emission from the three middle-aged pulsars PSR 1055-52, PSR 0656+14 and PSR 0630+18 (Geminga). The X-ray radiation from...
Accretion-Assisted Spindown of Young Radio Pulsars (2001)
Menou, Kristen, Perna, Rosalba, Hernquist, Lars
We present a model for the spindown of young radio pulsars in which the neutron star loses rotational energy not only by emitting magnetic dipole radiation but also by torquing a surrounding...
Anomalous X-ray Pulsars and Soft gamma-ray Repeaters: Spectral Fits and the Magnetar Model (2001)
Perna, Rosalba, Heyl, Jeremy, Hernquist, Lars, Juett, Adrienne, Chakrabarty, Deepto
The energy source powering the X-ray emission from anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) is still uncertain. In one scenario, the presence of an ultramagnetized neutron...
Stability and Evolution of Supernova Fallback Disks (2001)
Menou, Kristen, Perna, Rosalba, Hernquist, Lars
We show that thin accretion disks made of Carbon or Oxygen are subject to the same thermal ionization instability as Hydrogen and Helium disks. We argue that the instability applies to disks of any...
The halo model and numerical simulations (2000)
White, Martin, Hernquist, Lars, Springel, Volker
Recently there has been a lot of attention focussed on a virialized halo-based approach to understanding the properties of the matter and galaxy power spectrum. A key ingredient in this model is the...
Towards a Precise Measurement of Matter Clustering: Lyman-alpha Forest Data at Redshifts 2-4 (2000)
Croft, Rupert A. C., Weinberg, David H., Bolte, Mike, Burles, Scott, Hernquist, Lars, Katz, Neal, ...
We measure the filling factor, correlation function, and power spectrum of transmitted flux in a large sample of Lya forest spectra, comprised of 30 Keck HIRES spectra and 23 Keck LRIS spectra. We...
Models of Cuspy Triaxial Galaxies (2000)
Holley-Bockelmann, Kelly, Mihos, J. Christopher, Sigurdsson, Steinn, Hernquist, Lars
We construct numerical models of mildly triaxial elliptical galaxies with central density cusps. Using a technique we call ``adiabatic squeezing'', we begin with a spherical gamma=1 Hernquist model...
Hydrodynamic Simulation of the Cosmological X-ray Background (2000)
Croft, Rupert A. C., Di Matteo, Tiziana, Dav'e, Romeel, Hernquist, Lars, Katz, Neal, Fardal, Mark A., ...
(Abridged) We use a hydrodynamic simulation of a LambdaCDM model to predict the extragalactic X-ray background (XRB), focussing on emission from the intergalactic medium (IGM). We also include X-rays...
Disks irradiated by beamed radiation from compact objects (2000)
Perna, Rosalba, Hernquist, Lars
We examine the reprocessing of X-ray radiation from compact objects by accretion disks when the X-ray emission from the star is highly beamed. The reprocessed flux for various degrees of beaming and...
First Structure Formation: A Simulation of Small Scale Structure at High Redshift (2000)
Jang-Condell, Hannah, Hernquist, Lars
We describe the results of a simulation of collisionless cold dark matter in a LambdaCDM universe to examine the properties of objects collapsing at high redshift (z=10). We analyze the halos that...
Hydrodynamic Simulations of the Sunyaev-Zel'dovich effect(s) (2000)
Springel, Volker, White, Martin, Hernquist, Lars
We have performed a sequence of high resolution hydrodynamic simulations of structure formation in a LCDM model to study the thermal and kinetic Sunyaev-Zel'dovich (SZ) effects. Including only...
Baryons in the Warm-Hot Intergalactic Medium (2000)
Davé, Romeel, Cen, Renyue, Ostriker, Jeremiah P., Bryan, Greg L., Hernquist, Lars, Katz, Neal, ...
Approximately 30-40% of all baryons in the present day universe reside in a warm-hot intergalactic medium (WHIM), with temperatures between 10^5
Cooling Radiation and the Lyman-alpha Luminosity of Forming Galaxies (2000)
Fardal, Mark A., Katz, Neal, Gardner, Jeffrey P., Hernquist, Lars, Weinberg, David H., Davé, Romeel
We examine the cooling radiation from forming galaxies in hydrodynamic simulations of the LCDM model (cold dark matter with a cosmological constant), focusing on the Ly-alpha line luminosities of...
Enrichment of the Intergalactic Medium by Radiation Pressure Driven Dust Efflux (2000)
Aguirre, Anthony, Hernquist, Lars, Katz, Neal, Gardner, Jeffrey, Weinberg, David
The presence of metals in hot cluster gas and in Ly-alpha absorbers, as well as the mass-metallicity relation of observed galaxies, suggest that galaxies lose a significant fraction of their metals...
Metal Enrichment of the Intergalactic Medium at z=3 by Galactic Winds (2000)
Aguirre, Anthony, Hernquist, Lars, Schaye, Joop, Weinberg, David, Katz, Neal, Gardner, Jeffrey
Studies of quasar absorption lines reveal that the low density intergalactic medium at z ~ 3 is enriched to 0.001-0.01 solar metallicity. This enrichment may have occurred in an early generation of...
Consequences of Interstellar Absorption for Models of Anomalous X-ray Pulsars (2000)
Perna, Rosalba, Heyl, Jeremy, Hernquist, Lars
We examine properties of thermal radiation emitted by strongly magnetized neutron stars (NSs). In particular, we show that the pulsation amplitudes of the energy-integrated flux are an increasing...
The Spin Period, Luminosity and Age Distributions of Anomalous X-Ray Pulsars (2000)
Chatterjee, Pinaki, Hernquist, Lars
We consider the accretion model for anomalous X-ray pulsars proposed recently by Chatterjee, Hernquist and Narayan, in which the emission is powered by accretion from a fossil disk formed by the...
High-Redshift Galaxies in Cold Dark Matter Models (2000)
Weinberg, David H., Hernquist, Lars, Katz, Neal
We use hydrodynamic cosmological simulations to predict the star formation properties of high-redshift galaxies (z=2-6) in five variants of the inflationary cold dark matter scenario, paying...
Hotspot Emission from a Freely Precessing Neutron Star (2000)
Heyl, Jeremy S., Hernquist, Lars
Recent observations of 1E~161348-5055, the neutron-star candidate at the center of the supernova remnant RCW 103, show that a component of its emission varies sinusoidally with a period of...
Simulating the effects of intergalactic grey dust (2000)
Croft, Rupert A. C., Dave', Romeel, Hernquist, Lars, Katz, Neal
Using a high-resolution cosmological hydrodynamic simulation, we present a method to constrain extinction due to intergalactic grey dust based on the observed magnitudes of distant Type IA...
Phillips, John, Weinberg, David H., Croft, Rupert A. C., Hernquist, Lars, Katz, Neal, Pettini, Max
We combine COBE-DMR measurements of cosmic microwave background anisotropy with a recent measurement of the mass power spectrum at redshift z=2.5 from Lya forest data to derive constraints on...
Emission Spectra of Fallback Disks Around Young Neutron Stars (1999)
Perna, Rosalba, Hernquist, Lars, Narayan, Ramesh
The nature of the energy source powering anomalous X-ray pulsars is uncertain. Proposed scenarios involve either an ultramagnetized neutron star, or accretion onto a neutron star. We consider the...
An Accretion Model for Anomalous X-Ray Pulsars (1999)
Chatterjee, Pinaki, Hernquist, Lars, Narayan, Ramesh
We present a model for the anomalous X-ray pulsars (AXPs) in which the emission is powered by accretion from a fossil disk, established from matter falling back onto the neutron star following its...
Gardner, Jeffrey P., Katz, Neal, Hernquist, Lars, Weinberg, David H.
We use hydrodynamic cosmological simulations to study damped Lyman-alpha (DLA) and Lyman limit (LL) absorption at redshifts z=2-4 in five variants of the cold dark matter scenario. Our standard...
The Nature of Lyman Break Galaxies in Cosmological Hydrodynamic Simulations (1999)
Davé, Romeel, Gardner, Jeffrey P., Hernquist, Lars, Katz, Neal, Weinberg, David H.
What type of objects are being detected as $z\sim 3$ "Lyman break galaxies"? Are they predominantly the most massive galaxies at that epoch, or are many of them smaller galaxies undergoing a...
Evolution of Clustering and Bias in a Lambda-CDM Universe (1999)
Davé, Romeel, Hernquist, Lars, Katz, Neal, Weinberg, David H.
We determine the evolution from $z=3\to 0$ of the galaxy and mass correlation functions and bias factor in a $50h^{-1}$Mpc $\Lambda$CDM hydrodynamic simulation with $10h^{-1}$kpc resolution. The mass...
On the Formation of Boxy and Disky Elliptical Galaxies (1999)
Naab, Thorsten, Burkert, Andreas, Hernquist, Lars
The origin of boxy and disky elliptical galaxies is investigated. The results of two collisionless N-body simulations of spiral-spiral mergers with mass ratios of 1:1 and 3:1 are discussed and the...
Theoretical Modeling of the High Redshift Galaxy Population (1999)
Weinberg, David H., Dave', Romeel, Gardner, Jeffrey P., Hernquist, Lars, Katz, Neal
We review theoretical approaches to the study of galaxy formation, with emphasis on the role of hydrodynamic simulations in modeling the high redshift galaxy population. We present new predictions...
Evolution of the Galactic Potential and Halo Streamers with Future Astrometric Satellites (1999)
Zhao, HongSheng, Johnston, Kathryn, Hernquist, Lars, Spergel, David
ESA's Global Astrometric Interferometer for Astrophysics (GAIA) holds the promise of mapping out the detailed phase space structure of the Galactic halo by providing unprecedented annual proper...
Constraining Dark Halo Potentials with Tidal Tails (1999)
Dubinski, John, Mihos, J. Christopher, Hernquist, Lars
We present an extensive parameter survey to study the influence of halo mass profiles on the development of tidal tails in interacting disk galaxies. We model the galaxies using a fixed exponential...
Zhao, HongSheng, Johnston, Kathryn, Spergel, David, Hernquist, Lars
Future astrometric satellites, such as SIM (NASA's Space Interferometric Mission) and GAIA (ESA's Global Astrometric Interferometer for Astrophysics), hold the promise of mapping out the detailed...
Nonlinear QED Effects in Strong-Field Magnetohydrodynamics (1998)
Heyl, Jeremy S., Hernquist, Lars
We examine wave propagation and the formation of shocks in strongly magnetized plasmas by applying a variational technique and the method of characteristics to the coupled magnetohydrodynamic (MHD)...
Cosmology with the Lyman-alpha Forest (1998)
Weinberg, David H., Burles, Scott, Croft, Rupert A. C., Dave', Romeel, Gomez, Gilberto, Hernquist, Lars, ...
We outline the physical picture of the high-redshift Ly-alpha forest that has emerged from cosmological simulations, describe statistical characteristics of the forest that can be used to test...
Weinberg, David H., Croft, Rupert A. C., Hernquist, Lars, Katz, Neal, Pettinini, Max
We estimate the value of the matter density parameter \Omega_0 by combining constraints from the galaxy cluster mass function with Croft et al.'s recent measurement of the mass power spectrum, P(k),...
Croft, Rupert A. C., Weinberg, David H., Pettini, Max, Hernquist, Lars, Katz, Neal
We measure the linear power spectrum of mass density fluctuations at redshift z=2.5 from the \lya forest absorption in a sample of 19 QSO spectra, using the method introduced by Croft et al. (1998)....
Multidimensional thermal structure of magnetized neutron star envelopes (1998)
Heyl, Jeremy S., Hernquist, Lars
Recently launched x-ray telescopes have discovered several candidate isolated neutron stars. The thermal radiation from these objects may potentially constrain our understanding of nuclear physics in...
Do magnetars glitch? : Timing irregularities in anomalous X-ray pulsars (1998)
Heyl, Jeremy S., Hernquist, Lars
We examine the timing history of several anomalous X-ray pulsars (AXPs), and find that they exhibit spin down irregularities statistically similar to those of radio pulsars. We propose that these...
Tidal Streams as Probes of the Galactic Potential (1998)
Johnston, Kathryn V., Zhao, HongSheng, Spergel, David N., Hernquist, Lars
We explore the use of tidal streams from Galactic satellites to recover the potential of the Milky Way. Our study is motivated both by the discovery of the first lengthy stellar stream in the halo...
The Low Redshift Lyman Alpha Forest in Cold Dark Matter Cosmologies (1998)
Dave', Romeel, Hernquist, Lars, Katz, Neal, Weinberg, David
We study the physical origin of the low-redshift Lyman alpha forest in hydrodynamic simulations of four CDM cosmologies. Our main conclusions are insensitive to the cosmological model but depend on...
Hydrogen and Helium Atoms and Molecules in an Intense Magnetic Field (1998)
Heyl, Jeremy S., Hernquist, Lars
We calculate the atomic structure of hydrogen and helium, atoms and molecules in an intense magnetic field, analytically and numerically with a judiciously chosen basis.
The Clustering of High Redshift Galaxies in the Cold Dark Matter Scenario (1998)
Katz, Neal, Hernquist, Lars, Weinberg, David H.
We investigate the clustering of high redshift galaxies in five variants of the cold dark matter (CDM) scenario, using hydrodynamic cosmological simulations that resolve the formation of systems with...
Secular Evolution of Barred Galaxies with Massive Central Black Holes (1998)
Hozumi, Shunsuke, Hernquist, Lars
The influence of central black holes on the dynamical evolution of bars in disk galaxies is examined. In particular, we use numerical simulation to estimate the minimum mass black hole (BH) needed to...
Triaxial Halos and Cusps (1998)
Sigurdsson, Steinn, Mihos, Chris, Hernquist, Lars, Norman, Colin
We present $N$--body models for triaxial elliptical galaxies or halos of galaxies, which are fully self--gravitating, have near constant axis ratio as a function of radius and a $r^{-1}$ central...
Measuring Mass Loss Rates from Galactic Satellites (1998)
Johnston, Kathryn V., Sigurdsson, Steinn, Hernquist, Lars
We present the results of a study that uses numerical simulations to interpret observations of tidally disturbed satellites around the Milky Way. When analysing the simulations from the viewpoint of...
Almost Analytic Models of Ultramagnetized Neutron Star Envelopes (1998)
Heyl, Jeremy S., Hernquist, Lars
Recent ROSAT measurements show that the x-ray emission from isolated neutron stars is modulated at the stellar rotation period. To interpret these measurements, one needs precise calculations of the...
Electromagnetic Shocks in Strong Magnetic Fields (1998)
Heyl, Jeremy S., Hernquist, Lars
We examine the propagation of electromagnetic radiation through a strong magnetic field using the method of characteristics. Owing to nonlinear effects associated with vacuum polarization, such waves...
RCW 103 -- Revisiting a cooling neutron star (1998)
Heyl, Jeremy S., Hernquist, Lars
Recent observations of the compact source embedded within the supernova remnant RCW 103 rekindle interest in the origin of this object's emission. We contrast several models in which neutron-star...
Constraining the Metallicity of the Low Density Lyman-alpha Forest Using OVI Absorption (1998)
Davé, Romeel, Hellsten, Uffe, Hernquist, Lars, Katz, Neal, Weinberg, David
We search for OVI absorption in a Keck HIRES spectrum of the z=3.62 quasar Q1422+231. Comparison of CIV measurements to cosmological simulations shows that \lya forest absorbers with N_HI > 10^{14.5}...
Cosmology from the structure of the Lyman-alpha forest (1998)
Croft, Rupert, Weinberg, David, Katz, Neal, Hernquist, Lars
A convincing physical picture for the Lyman-alpha forest has emerged from simulations and related semi-analytic studies of structure formation models. Observations can be be used in the context of...
Simulating Gas at High Redshift (1998)
Katz, Neal, Hernquist, Lars, Weinberg, David H.
We discuss simulations of gas at high redshift. We briefly review the methods used and the results for quasar absorption lines. We present gas mass functions and galaxy correlation functions for 5...
What is the nature of RX J0720.4-3125? (1998)
Heyl, Jeremy S., Hernquist, Lars
RX J0720.4-3125 has recently been identified as a pulsating soft X-ray source in the ROSAT all-sky survey with a period of 8.391 s. Its spectrum is well characterized by a black-body with a...
Constraining dark halos with tidal tails (1997)
Dubinski, John, Mihos, Chris, Hernquist, Lars
Massive and extended dark halos can inhibit the formation of long tidal tails in galaxy collisions. We examine this effect using an extensive survey of simulations with different dark halo potentials...
The Thermal Evolution of Ultramagnetized Neutron Stars (1997)
Heyl, Jeremy S., Hernquist, Lars
Using recently calculated analytic and numerical models for the thermal structure of ultramagnetized neutron stars, we estimate the effects that ultrastrong magnetic fields $B \ge 10^{14}$ G have on...
Smooth Particle Hydrodynamics: Models, Applications, and Enabling Technologies (1997)
Hut, Piet, Hernquist, Lars, Lake, George, Makino, Jun, McMillan, Steve, Sterling, Thomas
We present the results from a two-day study in which we discussed various implementations of Smooth Particle Hydrodynamics (SPH), one of the leading methods used across a variety of areas of...
Hubble Flow Broadening of the Lyman-alpha Forest and its Implications (1997)
Weinberg, David H., Hernquist, Lars, Katz, Neal, Croft, Rupert, Miralda-Escudé, Jordi
Lyman-alpha forest lines in QSO spectra have typical widths of 20-50 km/s. Low column density absorbers in cosmological simulations are large, diffuse structures, and the Hubble flow across the...
Tidal Shocking by Extended Mass Distributions (1997)
Gnedin, Oleg Y., Hernquist, Lars, Ostriker, Jeremiah P.
We derive expressions for the tidal field exerted by a spherically symmetric galaxy having an extended mass distribution, and use our analysis to calculate tidal perturbations and heating of stars in...
Metal Lines in Cosmological Models of Lyman-Alpha Absorbers (1997)
Hellsten, Uffe, Hernquist, Lars, Katz, Neal, Weinberg, David
The metal absorption lines found in association with \lya absorbers of moderate to high HI column density contain valuable information about the metallicity and ionization conditions within the...
Simulating Cosmic Structure Formation (1997)
Weinberg, David H., Katz, Neal, Hernquist, Lars
We describe cosmological simulation techniques and their application to studies of cosmic structure formation, with particular attention to recent hydrodynamic simulations of structure in the high...
Powering Anomalous X-ray Pulsars by Neutron Star Cooling (1997)
Heyl, Jeremy S., Hernquist, Lars
Using recently calculated analytic models for the thermal structure of ultramagnetized neutron stars, we estimate the thermal fluxes from young ($t\sim 1000$ yr) ultramagnetized ($B \sim 10^{15}$ G)...
The Observability of Metal Lines Associated with the Lyman-alpha Forest (1997)
Hellsten, Uffe, Hernquist, Lars, Katz, Neal, Weinberg, David
We develop a prescription for characterizing the strengths of metal lines associated with Lyman-alpha forest absorbers (LYFAs) of a given neutral hydrogen column density N_HI and metallicity [Fe/H]....
Croft, Rupert A. C., Weinberg, David H., Katz, Neal, Hernquist, Lars
We present a method to recover the shape and amplitude of the power spectrum of mass fluctuations, P(k), from observations of the high redshift \lya forest. The method is motivated by the physical...
Tidal Tales Two: The Effect of Dark Matter Halos on Tidal Tail Morphology and Kinematics (1997)
Mihos, Chris, Dubinski, John, Hernquist, Lars
We examine the effect of different dark matter halo potentials on the morphology and kinematics of tidals tails in a merger model of NGC 7252. We find that models of merging galaxies with low halo...
Quinlan, Gerald D., Hernquist, Lars
We use a hybrid N-body program to study the evolution of massive black hole binaries in the centers of galaxies, mainly to understand the factors affecting the binary eccentricity, the response of...
Birefringence and Dichroism of the QED Vacuum (1997)
Heyl, Jeremy S., Hernquist, Lars
We use an analytic form for the Heisenberg-Euler Lagrangian to calculate the birefringent and dichroic properties of the vacuum for arbitrarily strong wrenchless fields. PACS : 12.20.Ds, 42.25.Lc...
QED One-loop Corrections to a Macroscopic Magnetic Dipole (1997)
Heyl, Jeremy S., Hernquist, Lars
We consider the field equations of a static magnetic field including one-loop QED corrections, and calculate the corrections to the field of a magnetic dipole. PACS: 12.20.Ds, 97.60.Jd, 97.60.Gb
Cosmological Constraints from High-Redshift Damped Lyman-Alpha Systems (1997)
Ma, Chung-Pei, Bertschinger, Edmund, Hernquist, Lars, Weinberg, David H., Katz, Neal
Any viable cosmological model must produce enough structure at early epochs to explain the amount of gas associated with high-redshift damped Ly$\alpha$ systems. We study the evolution of damped...
Testing Cosmological Models Against the Abundance of Damped Lyman-Alpha Absorbers (1997)
Gardner, Jeffrey P., Katz, Neal, Weinberg, David H., Hernquist, Lars
We calculate the number of damped Lyman-alpha absorbers expected in various popular cosmological models as a function of redshift and compare our predictions with observed abundances. The...
Cosmological Simulations with Scale-Free Initial Conditions I: Adiabatic Hydrodynamics (1997)
Owen, J. Michael, Weinberg, David H., Evrard, August E., Hernquist, Lars, Katz, Neal
We analyze hierarchical structure formation based on scale-free initial conditions in an Einstein-de Sitter universe, including a baryonic component. We present three independent, smoothed particle...
Croft, Rupert A. C., Weinberg, David H., Hernquist, Lars, Katz, Neal
In gravitational instability models, \lya absorption arises from a continuous fluctuating medium, so that spectra provide a non-linear one-dimensional ``map'' of the underlying density field. We...
Dave', Romeel, Dubinski, John, Hernquist, Lars
We describe PTreeSPH, a gravity treecode combined with an SPH hydrodynamics code designed for massively parallel supercomputers having distributed memory. Our computational algorithm is based on the...
Metal Lines Associated with Lyman Alpha Absorbers: A Comparison of Theory and Observations (1997)
Hellsten, Uffe, Dave, Romeel, Hernquist, Lars, Weinberg, David H., Katz, Neal
We study metal line absorption of CIV, CII, SiIV, and NV at redshifts z=3.5 to z=2 within the framework of a cosmological model for the Lyman alpha forest, comparing the results of numerical...
A Lower Bound on the Cosmic Baryon Density (1997)
Weinberg, David H., Miralda-Escude, Jordi, Hernquist, Lars, Katz, Neal
We derive analytic lower bounds on the cosmic baryon density by requiring that the high-redshift IGM contain enough neutral hydrogen to produce the observed \lya absorption in quasar spectra. The key...
Intergalactic Helium Absorption in Cold Dark Matter Models (1996)
Croft, Rupert A. C., Weinberg, David H., Katz, Neal, Hernquist, Lars
Observations from the HUT and the HST have recently detected HeII absorption along the lines of sight to two high redshift quasars. We use cosmological simulations with gas dynamics to investigate...
Composition Mixing during Blue Straggler Formation and Evolution (1996)
Sandquist, Eric L., Bolte, Michael, Hernquist, Lars
We use smoothed-particle hydrodynamics to examine differences between direct collisions of single stars and binary star mergers in their roles as possible blue straggler star formation mechanisms. We...
Voigt-Profile Analysis of the Lyman-alpha Forest in a Cold Dark Matter Universe (1996)
Davé, Romeel, Hernquist, Lars, Weinberg, David, Katz, Neal
We use an automated Voigt-profile fitting procedure to extract statistical properties of the Ly$\alpha$ forest in a numerical simulation of an $\Omega=1$, cold dark matter (CDM) universe. Our...
The Population of Damped Lyman-alpha and Lyman Limit Systems in the Cold Dark Matter Model (1996)
Gardner, Jeffrey P., Katz, Neal, Hernquist, Lars, Weinberg, David H.
Lyman limit and damped Lyman-alpha absorption systems probe the distribution of collapsed, cold gas at high redshift. Numerical simulations that incorporate gravity and gas dynamics can predict the...
Davé, Romeel, Hernquist, Lars, Weinberg, David H., Katz, Neal
We use an automated Voigt-profile fitting procedure to extract statistical properties of the Ly$\alpha$ forest in a numerical simulation of an $\Omega=1$, cold dark matter (CDM) universe. Our...
Magnetically Catalyzed Fusion (1996)
Heyl, Jeremy S., Hernquist, Lars
We calculate the reaction cross-sections for the fusion of hydrogen and deuterium in strong magnetic fields as are believed to exist in the atmospheres of neutron stars. We find that in the presence...
Heyl, Jeremy S., Hernquist, Lars
We derive an analytic form for the Heisenberg-Euler Lagrangian in the limit where the component of the electric field parallel to the magnetic field is small. We expand these analytic functions to...
Photoionization, Numerical Resolution, and Galaxy Formation (1996)
Weinberg, David H., Hernquist, Lars, Katz, Neal
Using cosmological simulations that incorporate gas dynamics and gravitational forces, we investigate the influence of photoionization by a UV radiation background on the formation of galaxies. In...
Fossil Signatures of Ancient Accretion Events in the Halo (1996)
Johnston, Kathryn V., Hernquist, Lars, Bolte, Michael
The role that minor mergers have played in the formation and structure of the Milky Way is still an open question, about which there is much debate. We use numerical simulations to explore the...
Gasdynamics and Starbursts in Major Mergers (1995)
Using numerical simulation, we study the development of gaseous inflows and triggering of starburst activity in mergers of comparable-mass disk galaxies. In all encounters studied, the galaxies...
Small Scale Structure and High Redshift HI (1995)
Weinberg, David H., Hernquist, Lars, Katz, Neal, Miralda-Escude, Jordi
Cosmological simulations with gas dynamics suggest that the Lyman-alpha forest is produced mainly by "small scale structure" --- filaments and sheets that are the high redshift analog of today's...
Quantifying the Fragility of Galactic Disks in Minor Mergers (1995)
Walker, Ian R., Mihos, J. Christopher, Hernquist, Lars
We perform fully self-consistent stellar dynamical simulations of the accretion of a companion ("satellite") galaxy by a large disk galaxy to investigate the interaction between the disk, halo, and...
The Lyman-alpha Forest in the Cold Dark Matter Model (1995)
Hernquist, Lars, Katz, Neal, Weinberg, David H., Miralda-Escude, Jordi
Cosmological simulations with gas provide a detailed description of the intergalactic medium, making possible predictions of neutral hydrogen absorption in the spectra of background QSOs. We present...
Damped Lyman-alpha and Lyman Limit Absorbers in the Cold Dark Matter Model (1995)
Katz, Neal, Weinberg, David H., Hernquist, Lars, Miralda-Escude, Jordi
We study the formation of damped \lya and Lyman limit absorbers in a hierarchical clustering scenario using a gas dynamical simulation of an $\Omega = 1$, cold dark matter universe. In the...
Cosmological Simulations with TreeSPH (1995)
Katz, Neal, Weinberg, David H., Hernquist, Lars
We describe numerical methods for incorporating gas dynamics into cosmological simulations and present illustrative applications to the cold dark matter (CDM) scenario. Our evolution code, a version...
Using Tidal Tails to Probe Dark Matter Halos (1995)
Dubinski, John, Mihos, J. Christopher, Hernquist, Lars
We use simulations of merging galaxies to explore the sensitivity of the morphology of tidal tails to variations of the halo mass distributions in the parent galaxies. Our goal is to constrain the...
Global Properties of Multiple Merger Remnants (1995)
Weil, Melinda L., Hernquist, Lars
Merger remnants of small groups of galaxies are contrasted with relics of mergers of pairs of galaxies to determine which process produces objects that best compare to real ellipticals. In both...
A Merger Origin for X-Structures in S0 Galaxies (1995)
Mihos, Chris, Walker, Ian, Hernquist, Lars, De Oliviera, Claudia Mendes, Bolte, Mike
Using numerical simulation, we study the response of a disk galaxy to a merger involving a low-mass satellite companion. During a prograde satellite accretion, the disk galaxy forms a strong bar in...
The Disruption of the Sagittarius Dwarf Galaxy. (1995)
Johnston, Kathryn V., Spergel, David N., Hernquist, Lars
Numerical simulations of dwarf spheroidal galaxies undergoing several close encounters with the Milky Way are described. By comparing our models to observed properties of the recently discovered...
Excitation of Activity in Galaxies by Minor Mergers (1995)
Mergers between gas--rich disks and less--massive dwarf galaxies are studied using numerical simulation. As the orbit of a satellite decays through dynamical friction, the primary disk develops...
A Parallel Self--Consistent Field Code (1995)
Hernquist, Lars, Sigurdsson, Steinn, Bryan, Greg L.
We describe a version of an algorithm for evolving self-gravitating collections of particles that should be nearly ideal for parallel architectures. Our method is derived from the ``self-consistent...
Using X-rays to Determine Which Compact Groups are Illusory (1994)
Ostriker, Jeremiah P., Lubin, Lori M., Hernquist, Lars
If the large-scale galaxy distribution is filamentary, as suggested by some observations and recent hydrodynamical simulations, then lengthwise views of filaments will apparently produce compact...
Dense Stellar Cores in Merger Remnants (1994)
We use numerical models which include star formation to analyze the mass profiles of remnants formed by mergers of disk galaxies. During a merger, dissipation in gas and ensuing star formation leave...
Models of Galaxies with Central Black Holes: Simulation Methods (1994)
Sigurdsson, Steinn, Hernquist, Lars, Quinlan, Gerald D.
We present a method for simulating numerically the effect of the adiabatic growth of black holes on the structure of elliptical galaxies. Using a parallel self--consistent field code, we add black...
Physically Detached "Compact Groups" (1994)
Hernquist, Lars, Katz, Neal, Weinberg, David
A small fraction of galaxies appear to reside in dense compact groups, whose inferred crossing times are much shorter than a Hubble time. These short crossing times have led to considerable...
Models of Galaxies with Central Black Holes: Adiabatic Growth in Spherical Galaxies (1994)
Quinlan, Gerald D., Hernquist, Lars, Sigurdsson, Steinn
We add black holes to nonrotating, spherical galaxy models, with the assumption that the black-hole growth is slow compared with the dynamical time but fast compared with the relaxation time. The...
Star Forming Galaxy Models: Blending Star Formation into TREESPH (1994)
We have incorporated star formation algorithms into a hybrid N-body/smoothed particle hydrodynamics code (TREESPH) in order to describe the star forming properties of disk galaxies over timescales of...
Ultraluminous Starbursts in Major Mergers (1994)
We use numerical simulation to investigate the triggering of starbursts in merging disk galaxies. The properties of the merger-driven starbursts are sensitive to the structure of the progenitor...
A Comparison of Cosmological Hydrodynamic Codes (1994)
Kang, Hyesung, Ostriker, Jeremiah P., Cen, Renyue, Ryu, Dongsu, Hernquist, Lars, Evrard, August E., ...
We present a detailed comparison of the simulation results of various cosmological hydrodynamic codes. Starting with identical initial conditions based on the Cold Dark Matter scenario for the growth...
Thermal and magnetic properties of neutron stars / (1985)
Thesis (Ph. D.)--California Institute of Technology, 1985.
Thermal and magnetic properties of neutron stars (1984)
The interaction of the magnetic field with the heat flux in neutron stars is investigated. It is proposed that the magnetic field develops as a result of thermal processes in the liquid and solid...