Joshua D. Younger

Mergers, AGN, and 'Normal' Galaxies: Contributions to the Distribution of Star Formation Rates and Infrared Luminosity Functions (2009)

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...

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...

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...

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...

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...

The Physical Scale of the Far-Infrared Emission in the Most Luminous Submillimeter Galaxies (2008)

Younger, Joshua D., Fazio, Giovanni G., Wilner, David J., Ashby, Matthew L. N., Blundell, Raymond, Gurwell, Mark A., ...

We present high resolution submillimeter interferometric imaging of two of the brightest high-redshift submillimeter galaxies known: GN20 and AzTEC1 at 0.8 and 0.3 arcsec resolution respectively. Our...

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...

The Radical Consequences of Realistic Satellite Orbits for the Heating and Implied Merger Histories of Galactic Disks (2008)

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...

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...

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...

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...

Evidence for a Population of High-Redshift Submillimeter Galaxies from Interferometric Imaging (2007)

Younger, Joshua D., Fazio, Giovanni G., Huang, Jia-Sheng, Yun, Min S., Wilson, Grant W., Ashby, Matthew L. N., ...

We have used the Submillimeter Array to image a flux limited sample of seven submillimeter galaxies, selected by the AzTEC camera on the JCMT at 1.1 mm, in the COSMOS field at 890um with 2"...

Rest-Frame Ultraviolet to Near Infrared Observations of an Interacting Lyman Break Galaxy at z = 4.42 (2007)

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...

Cosmological Simulations of the Preheating Scenario for Galaxy Cluster Formation: Comparison to Analytic Models and Observations (2007)

Younger, Joshua D., Bryan, Greg L.

We perform a set of non--radiative cosmological simulations of a preheated intracluster medium in which the entropy of the gas was uniformly boosted at high redshift. The results of these simulations...

Evidence for a population of high-redshift submillimeter galaxies from interferometric imaging (2007)

Younger, Joshua D., Fazio, Giovanni G., Huang, Jia-Sheng, Yun, Min S., Wilson, Grant W., Ashby, Matthew L. N., ...

We have used the Submillimeter Array to image a flux-limited sample of seven submillimeter galaxies, selected by the AzTEC camera on the JCMT at 1.1 mm, in the COSMOS field at 890 mum with ~2"...

Breaking Cosmological Degeneracies in Galaxy Cluster Surveys with a Physical Model of Cluster Structure (2006)

Younger, Joshua D., Haiman, Zoltan, Bryan, Greg L., Wang, Sheng

Forthcoming large galaxy cluster surveys will yield tight constraints on cosmological models. It has been shown that in an idealized survey, containing > 10,000 clusters, statistical errors on dark...

Evolution of the Cluster Mass and Correlation Functions in LCDM Cosmology (2004)

Younger, Joshua D., Bahcall, Neta A., Bode, Paul

The evolution of the cluster mass function and the cluster correlation function from z = 0 to z = 3 are determined using 10^6 clusters obtained from high-resolution simulations of the current...

An Empirical Algorithm for Broad-band Photometric Redshifts of Quasars from the Sloan Digital Sky Survey (2004)

Weinstein, Michael A., Richards, Gordon T., Schneider, Donald P., Younger, Joshua D., Strauss, Michael A., Hall, Patrick B., ...

We present an empirical algorithm for obtaining photometric redshifts of quasars using 5-band Sloan Digital Sky Survey (SDSS) photometry. Our algorithm generates an empirical model of the quasar...