Joseph Silk

The Sunyaev-Zel'dovich effect and Faraday rotation contributions of galaxy groups to the CMB angular power spectrum (2008)

Global star formation is the key to understanding galaxy disk formation. This in turn depends on gravitational instability of disks and continuing gas accretion as well as minor merging. A key...

Tashiro, Hiroyuki, Silk, Joseph, Langer, Mathieu, Sugiyama, Naoshi

The S-Z effect and Faraday rotation from halos are examined over a wide mass range, an including gas condensation and magnetic field evolution. Contributions to the CMB angular power spectrum are...

Delayed Recombination and Cosmic Parameters (2008)

Galli, Silvia, Bean, Rachel, Melchiorri, Alessandro, Silk, Joseph

Current cosmological constraints from Cosmic Microwave Background (CMB) anisotropies are typically derived assuming a standard recombination scheme, however additional resonance and ionizing...

New Frontiers in Cosmology and Galaxy Formation: Challenges for the Future (2007)

Ellis, Richard, Silk, Joseph

(Abridged) Cosmology faces three distinct challenges in the next decade. (1) The dark sector, both dark matter and dark energy, dominates the Universe. Key questions include determining the nature of...

Clusters, Clustering and a Constraint on Primordial Non-Gaussianity (2007)

James Robinson Eric, Eric Gawiser, Joseph Silk

. We show how the number density and clustering strength of present day clusters of galaxies can be used to constrain non-gaussianity in the primordial fluctuations in the universe. 1. Introduction...

Star-Formation as a Cosmological Probe (2007)

James Robinson, Joseph Silk

We discuss the cosmological dependence of the star-formation history of the universe, within the framework of a very simple semi-analytic model, where star-formation occurs within the virialized...

Baryonic Dark Halos: A Model With Machos And Cold Gas Globules (2007)

Ortwin Gerhard, Joseph Silk

. The dark matter in the halos of galaxies may well be baryonic, and much of the mass within them could be in the form of clusters of substellar objects within which are embedded cold gas globules....

Can Baryonic Features Produce the Observed (2007)

Gamma Mpc, Mpc Clustering, Daniel J. Eisenstein, Wayne Hu, Joseph Silk, Alexander S. Szalay

We assess the possibility that baryonic acoustic oscillations in adiabatic models may explain the observations of excess power in large-scale structure on 100h \Gamma1 Mpc scales. The observed...

Departments of Astronomy and Physics, and (2007)

Max Tegmark, Joseph Silk

One still cannot conclusively assert that the universe underwent a neutral phase, despite the new COBE FIRAS limit y! 2:5 \Theta 10 \Gamma5 on Compton y-distortions of the cosmic microwave...

On the Inevitability of Reionization: Implications for Cosmic Microwave Background Fluctuations y (2007)

Max Tegmark, Joseph Silk

Early photoionization of the intergalactic medium is discussed in a nearly model-independent way, in order to investigate whether early structures corresponding to rare Gaussian peaks in a CDM model...

1 (2007)

Max Tegmark, Joseph Silk, Martin J. Rees, Alain Blanchard, Francesco Palla, Fohringer Ring, ...

The minimum mass that a virialized gas cloud must have in order to be able to cool in a Hubble time is computed, using a detailed treatment of the chemistry of molecular hydrogen. With a simple model...

The role of minor mergers in the recent star formation history of early-type galaxies (2007)

Kaviraj, Sugata, Peirani, Sebastien, Khochfar, Sadegh, Silk, Joseph, Kay, Scott

We demonstrate that the large scatter in the ultra-violet (UV) colours of intermediate-mass early-type galaxies in the local Universe and the inferred low-level recent star formation in these objects...

Secondary anisotropies of the CMB (2007)

Aghanim, Nabila, Majumdar, Subhabrata, Silk, Joseph

The Cosmic Microwave Background fluctuations provide a powerful probe of the dark ages of the universe through the imprint of the secondary anisotropies associated with the reionisation of the...

Observational evidence for AGN feedback in early-type galaxies (2007)

Schawinski, Kevin, Thomas, Daniel, Sarzi, Marc, Maraston, Claudia, Kaviraj, Sugata, Joo, Seok-Joo, ...

A major amendment in recent models of hierarchical galaxy formation is the inclusion of so-called AGN feedback. The energy input from an active central massive black hole is invoked to suppress star...

On the Magnitude of Dark Energy Voids and Overdensities (2007)

Mota, David F., Shaw, Douglas J., Silk, Joseph

We investigate the clustering of dark energy within matter overdensities and voids. In particular, we derive an analytical expression for the dark energy density perturbations, which is valid both in...

Accounting for the Unresolved X-ray Background with Sterile Neutrino Dark Matter (2007)

Cumberbatch, Daniel, Silk, Joseph

We consider a scenario where keV sterile neutrinos constitute all of the currently inferred dark matter abundance, whose radiative decays could potentially account for the flux contributions to the...

A new test of the light dark matter hypothesis (2007)

Boehm, Celine, Silk, Joseph

Detection of a surprisingly high flux of positron annihilation radiation from the inner galaxy has motivated the proposal that dark matter is made of weakly interacting light particles (possibly as...

Solving the cosmic lithium problems with primordial late-decaying particles (2007)

Cumberbatch, Daniel, Ichikawa, Kazuhide, Kawasaki, Masahiro, Kohri, Kazunori, Silk, Joseph, Starkman, Glenn D.

We investigate the modifications to predictions for the abundances of light elements from standard Big-Bang nucleosynthesis when exotic late-decaying particles with lifetimes exceeding ~1 sec are...

Is WMAP3 normalization compatible with the X-Ray cluster abundance? (2007)

Yepes, Gustavo, Sevilla, Raul, Gottloeber, Stefan, Silk, Joseph

We present the mass and X-ray temperature functions derived from a sample of more than 15,000 galaxy clusters of the MareNostrum Universe cosmological SPH simulations. In these simulations, we follow...

Constraints on CPT violation from WMAP three year polarization data: a wavelet analysis (2007)

Cabella, Paolo, Natoli, Paolo, Silk, Joseph

We perform a wavelet analysis of the temperature and polarization maps of the Cosmic Microwave Background (CMB) delivered by the WMAP experiment in search for a parity violating signal. Such a signal...

Dark matter caustics and the enhancement of self-annihilation flux (2007)

Mohayaee, Roya, Shandarin, Sergei, Silk, Joseph

Cold dark matter haloes are populated by caustics, which are yet to be resolved in N-body simulations or observed in the Universe. Secondary infall model provides a paradigm for the study of caustics...

Cross-correlation studies as a probe of reionization physics (2007)

Slosar, Anze, Cooray, Asantha, Silk, Joseph

The process of reionization is now believed to have proceeded in an orchestrated manner beginning with UV photons emitted by high redshift galaxies containing a large fraction of Population III stars...

Tidal Disruption of the First Dark Microhalos (2007)

Zhao, HongSheng, Hooper, Dan, Angus, Garry W., Taylor, James E., Silk, Joseph

We point out that the usual self-similarity in cold dark matter models is broken by encounters with individual normal galactic stars on a subparsec scale. Tidal heating and stripping must have...

New constraints on macroscopic compact objects as dark matter candidates from gravitational lensing of type Ia supernovae (2007)

Local Voids as the Origin of Large-angle Cosmic Microwave Background Anomalies: The Effect of a Cosmological Constant (2006)

Inoue, Kaiki Taro, Silk, Joseph

We explore the large angular scale temperature anisotropies in the cosmic microwave background (CMB) due to homogeneous local dust-filled voids in a flat Friedmann-Robertson-Walker universe with a...

New Constraints on Macroscopic Compact Objects as a Dark Matter Candidate from Gravitational Lensing of Type Ia Supernovae (2006)

Disk Galaxy Evolution Along the Hubble Sequence (2006)

We use the distribution, and particularly the skewness, of high redshift type Ia supernovae brightnesses relative to the low redshift sample to constrain the density of macroscopic compact objects...

Kampakoglou, Marios, Silk, Joseph

Galaxy disks are characterised by star formation histories that vary systematically along the Hubble sequence. We study global star formation, incorporating supernova feedback, gas accretion and...

Luminosity Function of Faint Globular Clusters in M87 (2006)

Waters, Christopher Z., Zepf, Stephen E., Lauer, Tod R., Baltz, Edward A., Silk, Joseph

We present the luminosity function to very faint magnitudes for the globular clusters in M87, based on a 30 orbit \textit{Hubble Space Telescope (HST)} WFPC2 imaging program. The very deep images and...

Difficulties for Compact Composite Object Dark Matter (2006)

Cumberbatch, Daniel T., Starkman, Glenn D., Silk, Joseph

It has been suggested ``that DM particles are strongly interacting composite macroscopically large objects ... made of well known light quarks (or ... antiquarks)." In doing so it is argued that...

On the First Generation of Stars (2006)

Silk, Joseph, Langer, Mathieu

We argue that the first stars may have spanned the conventional mass range rather than be identified with the Very Massive Objects (100-1000 solar masses) favoured by numerical simulations....

A simple model for the size-evolution of elliptical galaxies (2006)

Khochfar, Sadegh, Silk, Joseph

We use semi-analytical modelling of galaxy formation to predict the redshift-size-evolution of elliptical galaxies. Using a simple model in which relative sizes of elliptical galaxies of a given mass...

Galaxy Formation and Dark Matter (2006)

Suppressing cluster cooling flows by self-regulated heating from spatially distributed population of AGNs (2006)

The challenge of dark matter may be addressed in two ways; by studying the confrontation of structure formation with observation and by direct and indirect searches. In this review, I will focus on...

Nusser, Adi, Silk, Joseph, Babul, Arif

(Abridged) Existing models invoking AGN activty to resolve the cooling flow conundrum in galaxy clusters focus exclusively on the role of the central galaxy. Such models require fine-tuning of highly...

Local Voids as the Origin of Large-angle Cosmic Microwave Background Anomalies I (2006)

Inoue, Kaiki Taro, Silk, Joseph

We explore the large angular scale temperature anisotropies in the cosmic microwave background due to expanding homogeneous local voids at redshift z~1. A compensated spherically symmetric...

Local dark matter clumps and the cosmic ray positron excess (2006)

Cumberbatch, Daniel T., Silk, Joseph

It has been proposed that the excess in cosmic ray positrons at approximately 8 GeV, observed on both flights of the HEAT balloon experiment, may be associated with the annihilation of dark matter...

Cosmic rays, lithium abundance and excess entropy in galaxy clusters (2006)

Nath, Biman B., Madau, Piero, Silk, Joseph

Restricted Access. An Open Access version is available at arXiv.org.

Pregalactic Black Hole Formation with an Atomic Hydrogen Equation of State (2006)

Spaans, Marco, Silk, Joseph

The polytropic equation of state of an atomic hydrogen gas is examined for primordial halos with baryonic masses of M_h~10^7-10^9 Mo. For roughly isothermal collapse around 10^4 K, we find that line...

The Infinite Cosmos : Questions from the Frontiers of Cosmology (2006)

Cosmic rays, lithium abundance and excess entropy in galaxy clusters (2005)

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Nath, Biman B., Madau, Piero, Silk, Joseph

We consider the production of $^6$Li in spallation reactions by cosmic rays in order to explain the observed abundance in halo metal-poor stars. We show that heating of ambient gas by cosmic rays is...

Cosmic Star Formation, Reionization, and Constraints on Global Chemical Evolution (2005)

Daigne, Frederic, Olive, Keith A., Vangioni-Flam, Elisabeth, Silk, Joseph, Audouze, Jean

Motivated by the WMAP results indicating an early epoch of reionization, we consider alternative cosmic star formation models which are capable of reionizing the early intergalactic medium. We...

AGN Feedback Causes Downsizing (2005)

Scannapieco, Evan, Silk, Joseph, Bouwens, Rychard

We study the impact of outflows driven by active galactic nuclei (AGN) on galaxy formation. Outflows move into the surrounding intergalactic medium (IGM) and heat it sufficiently to prevent it from...

A New Signature of Dark Matter Annihilations: Gamma-Rays from Intermediate-Mass Black Holes (2005)

Bertone, Gianfranco, Zentner, Andrew R., Silk, Joseph

We study the prospects for detecting gamma-rays from Dark Matter (DM) annihilations in enhancements of the DM density (mini-spikes) around intermediate-mass black holes with masses in the range $10^2...

Non-parametric reconstruction of the primordial power spectrum at horizon scales from WMAP data (2005)

Tocchini-Valentini, Domenico, Hoffman, Yehuda, Silk, Joseph

We extend to large scales a method proposed in previous work that reconstructs non-parametrically the primordial power spectrum from cosmic microwave background data at high resolution. The...

Ultraluminous Starbursts from SMBH-induced outflows (2005)

Observational Evidence for Extra Dimensions from Dark Matter (2005)

I argue that there are two modes of global star formation. Disks and smaller spheroids form stars relatively inefficiently as a consequence of supernova-triggered negative feedback via a sequence of...

Qin, Bo, Pen, Ue-Li, Silk, Joseph

Recent astronomical observations of systems of dark matter, which have been cited as providing possible support for self-interacting cold dark matter, may provide evidence for the extra dimensions...

Tidal Destruction of The First Dark Microhalos (2005)

Zhao, HongSheng, Hooper, Dan, Angus, Garry W., Taylor, James E., Silk, Joseph

We point out that the usual self-similarity in cold dark matter models is broken by encounters with individual normal galactic stars on sub-pc scale. Tidal heating and stripping must have redefined...

Did Boomerang hit MOND? (2005)

Slosar, Anze, Melchiorri, Alessandro, Silk, Joseph

Purely baryonic dark matter dominated models like MOND based on modification of Newtonian gravity have been successfully in reproducing some dynamical properties of galaxies. More recently, a...

New constraints on MOND from galaxy clusters (2005)

Pointecouteau, Etienne, Silk, Joseph

We revisit the application of Modified Newtonian Dynamics (MOND) to galaxy clusters. We confront the high quality X-ray data for eight clusters of galaxies observed by the \xmm satellite with the...

Probing the Origins of Voids in the Distribution of Galaxies (2005)

Ord, Louise M., Kunz, Martin, Mathis, Hugues, Silk, Joseph

If the voids that we see today in the distribution of galaxies existed at recombination, they will leave an imprint on the cosmic microwave background (CMB). On the other hand, if these voids formed...

Population III and the Near-Infrared Background Excess (2005)

Madau, Piero, Silk, Joseph

We make a critical assessment of models that attribute the recently detected near-infrared background ``excess'' (NIRBE) to the redshifted light from Population III objects. To supply the required 25...

Earth-mass dark halos are torn into dark mini-streams by stars (2005)

Zhao, HongSheng, Taylor, James E., Silk, Joseph, Hooper, Dan

The promising neutralino dark matter particles generically condense into numerous earth-mass dark halos with smaller substructures suppressed by free streaming\cite{berezinsky}. The recent {\it...

Mini-dark halos with intermediate mass black holes (2005)

Zhao, HongSheng, Silk, Joseph

We argue that the Milky Way (MW) contains thousands intermediate mass black holes (IMBHs) and minihalos with a fraction of IMBHs still being enshrouded in extremely dense mini-spikes of dark matter...

Reconstruction of primordial density fields (2005)

Mohayaee, Roya, Mathis, Hugues, Colombi, Stephane, Silk, Joseph

The Monge-Ampere-Kantorovich (MAK) reconstruction is tested against cosmological N-body simulations. Using only the present mass distribution sampled with particles, and the assumption of homogeneity...

The Polytropic Equation of State of Primordial Gas Clouds (2004)

Spaans, Marco, Silk, Joseph

The polytropic equation of state (EOS) of primordial gas clouds with modest enrichment is computed, motivated by the recent observations of very Fe-deficient stars, [Fe/H]~10^{-3.5}-10^{-5}, such as...

Dark Matter and Galaxy Formation: Challenges for the Next Decade (2004)

LOFAR as a Probe of the Sources of Cosmological Reionisation (2004)

The origin of the galaxies represents an important focus of current cosmological research, both observational and theoretical. Its resolution involves a comprehensive understanding of star formation,...

Zaroubi, Saleem, Silk, Joseph

We propose use of the thickness of the ionisation front as a discriminant between alternative modes of reionisation in the early universe, by stars or by miniquasars. Assuming a...

Towards simulating star formation in the interstellar medium (2004)

Slyz, A., Devriendt, J., Bryan, Greg, Silk, Joseph

As a first step to a more complete understanding of the local physical processes which determine star formation rates (SFRs) in the interstellar medium (ISM), we have performed controlled numerical...

Feedback and the Initial Mass function (2004)

Searching for Dark Matter with Future Cosmic Positron Experiments (2004)

I describe a turbulence-inspired model for the stellar initial mass function which includes feedback and self-regulation via protostellar outflows. A new aspect of the model provides predictions of...

Hooper, Dan, Silk, Joseph

Dark matter particles annihilating in the Galactic halo can provide a flux of positrons potentially observable in upcoming experiments, such as PAMELA and AMS-02. We discuss the spectral features...

Cosmic Star Formation, Reionization, and Constraints on Global Chemical Evolution (2004)

Daigne, Frederic, Olive, Keith A., Vangioni-Flam, Elisabeth, Silk, Joseph, Audouze, Jean

Motivated by the WMAP results indicating an early epoch of reionization, we consider alternative cosmic star formation models which are capable of reionizing the early intergalactic medium. We...

Particle Dark Matter: Evidence, Candidates and Constraints (2004)

Bertone, Gianfranco, Hooper, Dan, Silk, Joseph

In this review article, we discuss the current status of particle dark matter, including experimental evidence and theoretical motivations. We discuss a wide array of candidates for particle dark...

Have Atmospheric Cerenkov Telescopes Observed Dark Matter? (2004)

Hooper, Dan, Silk, Joseph, Ferrer, Francesc, Sarkar, Subir

Two ground-based experiments have recently independently detected TeV $\gamma$-rays from the direction of the Galactic center. The observations made by the VERITAS and CANGAROO collaborations are...

Neutrinos from Dark Matter annihilations at the Galactic Centre (2004)

Bertone, Gianfranco, Nezri, Emmanuel, Orloff, Jean, Silk, Joseph

We discuss the prospects for detection of high energy neutrinos from dark matter annihilation at the Galactic centre. Despite the large uncertainties associated with our poor knowledge of the...

A new search for features in the primordial power spectrum (2004)

Tocchini-Valentini, Domenico, Douspis, Marian, Silk, Joseph

We develop a new approach toward a high resolution non-parametric reconstruction of the primordial power spectrum using WMAP cosmic microwave background temperature anisotropies that we confront with...

Are Domain Walls ruled out ? (2004)

Conversi, Luca, Melchiorri, Alessandro, Mersini, Laura, Silk, Joseph

Recent analysis of the combined data of cosmic microwave background, galaxy clustering and supernovae type Ia observations have set strong constraints on the equation of state parameter $w_X$. The...

A new method for measuring the CMB temperature quadrupole with an accuracy better than cosmic variance (2004)

Skordis, Constantinos, Silk, Joseph

We present a new method for measuring the CMB temperature quadrupole, using large scale CMB polarization. The method exploits the fact that CMB polarization is partially sourced by the local...

The case for non-gaussianity on cluster scales (2004)

Mathis, H., Diego, J. M., Silk, Joseph

We address whether possible scale-dependent deviations from gaussianity in the primordial density field that are consistent with the cosmic microwave background observations could explain the...

An Erupting Classical Nova in a Globular Cluster of M87 (2004)

Shara, Michael M., Zurek, David R., Baltz, Edward A., Lauer, Tod R., Silk, Joseph

Only one certain classical nova eruption has ever been detected inside a globular cluster - nova 1860 A.D. (T Sco) in M80. During a survey of M87 we have detected an erupting star coincident (to...

Some Current Issues in Galaxy Formation (2004)

A simple model for the evolution of super-massive black holes and the quasar population (2004)

I describe recent challenges in hierarchical galaxy formation theory, including the formation of disk galaxies and of ellipticals. Problems with cold dark matter are summarized, and possible...

Mahmood, Asim, Devriendt, Julien E. G., Silk, Joseph

An empirically motivated model is presented for accretion-dominated growth of the super massive black holes (SMBH) in galaxies, and the implications are studied for the evolution of the quasar...

Cosmic Star Formation, Reionization, and Constraints on Global Chemical Evolution (2004)

Daigne, Frederic, Olive, Keith A., Vangioni-Flam, Elisabeth, Silk, Joseph, Audouze, Jean

Motivated by the WMAP results indicating an early epoch of reionization, we consider alternative cosmic star formation models which are capable of reionizing the early intergalactic medium. We...

Cosmic Star Formation, Reionization, and Constraints on Global Chemical Evolution (2004)

Daigne, Frederic, Olive, Keith A., Vangioni-Flam, Elisabeth, Silk, Joseph, Audouze, Jean

Motivated by the WMAP results indicating an early epoch of reionization, we consider alternative cosmic star formation models which are capable of reionizing the early intergalactic medium. We...

Isocurvature fluctuations induce early star formation (2004)

Sugiyama, Naoshi, Zaroubi, Saleem, Silk, Joseph

Can Supersymmetry Naturally Explain the Positron Excess? (2003)

Hooper, Dan, Taylor, James E., Silk, Joseph

It has often been suggested that the cosmic positron excess observed by the HEAT experiment could be the consequence of supersymmetric dark matter annihilating in the galactic halo. Although it is...

Small-scale Substructure in Dark Matter Haloes: Where Does Galaxy Formation Come to an End? (2003)

Taylor, James E., Silk, Joseph, Babul, Arif

Models of structure formation based on cold dark matter predict that most of the small dark matter haloes that first formed at high redshift would have merged into larger systems by the present...

Searching For Dark Matter with Neutrino Telescopes (2003)

Hooper, Dan, Silk, Joseph

One of the most interesting mysteries of astrophysics is the puzzle of dark matter. Although numerous techniques have been explored and developed to detect this elusive substance, its nature remains...

The Satellite-substructure Connection (2003)

Taylor, James E., Babul, Arif, Silk, Joseph

We describe our recent attempts to model substructure in dark matter halos down to very small masses, using a semi-analytic model of halo formation. The results suggest that numerical simulations of...

Possible Evidence for MeV Dark Matter In Dwarf Spheroidals (2003)

Hooper, Dan, Ferrer, Francesc, Boehm, Céline, Silk, Joseph, Paul, Jacques, Evans, N. Wyn, ...

It has been recently proposed that the observed 511 keV emission from the Galactic bulge could be the product of very light (1-100 MeV) annihilating dark matter particles. Other possible explanations...

Microlensing Candidates in M87 and the Virgo Cluster with the Hubble Space Telescope (2003)

Baltz, Edward A., Lauer, Tod R., Zurek, David R., Gondolo, Paolo, Shara, Michael M., Silk, Joseph, ...

The position of the giant elliptical galaxy M87 at the center of the Virgo Cluster means that the inferred column density of dark matter associated with both the cluster halo and the galaxy halo is...

Isocurvature Fluctuations Induce Early Star Formation (2003)

Sugiyama, Naoshi, Zaroubi, Saleem, Silk, Joseph

The early reionisation of the Universe inferred from the WMAP polarisation results, if confirmed, poses a problem for the hypothesis that scale-invariant adiabatic density fluctuations account for...

MeV Dark Matter: Has It Been Detected? (2003)

Boehm, Celine, Hooper, Dan, Silk, Joseph, Casse, Michel

We discuss the possibility that the recent detection of 511 keV gamma-rays from the galactic bulge, as observed by INTEGRAL, is a consequence of low mass (~MeV) particle dark matter annihilations. We...

Massive black hole remnants of the first stars II: optical and X-ray signatures in present-day galactic haloes (2003)

Massive black hole remnants of the first stars III: observational signatures from the past (2003)

The first stars forming in minihaloes at redshifts greater than 20 may have been very massive and could have left behind massive black hole (MBH) remnants. In a previous paper we investigated the...

Massive black hole remnants of the first stars I: abundance in present-day galactic haloes (2003)

The first stars forming in minihaloes at redshifts greater than 20 may have been very massive and could have left behind massive black hole (MBH) remnants. In previous papers we investigated the...

Top-Down Fragmentation of a Warm Dark Matter Filament (2003)

We investigate the possibility that present-day galaxies and their dark matter haloes contain a population of massive black holes (MBHs) that form by hierarchical merging of the black hole remnants...

Knebe, Alexander, Devriendt, Julien, Gibson, Brad, Silk, Joseph

We present the first high-resolution n-body simulations of the fragmentation of dark matter filaments. Such fragmentation occurs in top-down scenarios of structure formation, when the dark matter is...

Near and far: the star formation history of disk galaxies Elektronische Daten (2003)

Ferreras, Ignacio, Silk, Joseph, Astrophysics Conference

Talk Abstract von Kongress: Star and Structure Formation: From First Light to the Milky Way, Astrophysics Conference, August 18-22, 2003, ETH Zurich, Switzerland

Star formation in a multi-phase interstellar medium (2003)

Slyz, Adrianne, Devriendt, Julien, Bryan, Greg, Silk, Joseph

This contribution reports on our first efforts to simulate a multiphase interstellar medium on a kiloparsec scale in three dimensions with the stars and gas modeled self-consistently. Starting from...

Cosmological Constraints from a Combined Analysis of the Cluster Mass Function and Microwave Background Anisotropies (2002)

Melchiorri, Alessandro, Bode, Paul, Bahcall, Neta A., Silk, Joseph

We present constraints on several cosmological parameters from a combined analysis of the most recent Cosmic Microwave Background anisotropy data and the Sloan Digital Sky Survey cluster mass...

The Cosmic Microwave Background (2002)

A New Prescription for Protogalactic Feedback and Outflows: Where Have All the Baryons Gone? (2002)

I review the discovery of the temperature fluctuations in the cosmic microwave background radiation. The underlying theory and the implications for cosmology are reviewed, and I describe the...

Formation and Evolution of Disk Galaxies (2002)

Up to half of the baryons inferred to once have been in our galaxy have not yet been detected. Ejection would seem to provide the most attractive explanation. Previous numerical studies may have...

Indirect detection of a subdominant density component of cold dark matter (2002)

I review several of the current issues in the theory of disk galaxy formation. There is sti ll much to be done, observationally and theoretically, before we can expect to approach an understanding of...

Duda, Gintaras, Gelmini, Graciela, Gondolo, Paolo, Edsjo, Joakim, Silk, Joseph

We examine the detectability through indirect means of weakly interacting dark matter candidates that may constitute not all but only a subdominant component of galactic cold dark matter. We show...

Massive black hole remnants of the first stars in galactic haloes (2002)

Type Ia supernovae and the formation history of early-type galaxies (2002)

We investigate the possibility that present-day galactic haloes contain a population of massive black holes (MBHs) that form by hierarchical merging of the black hole remnants of the first stars....

Ferreras, Ignacio, Silk, Joseph

Using the standard prescription for the rates of supernovae type II and type Ia, we compare the predictions of a simple model of star formation in galaxies with the observed radial gradients of...

Feedback Processes in Early-Type Galaxies (2002)

Ferreras, Ignacio, Scannapieco, Evan, Silk, Joseph

We present a phenomenological model of feedback in early-type galaxies that tracks the evolution of the interstellar medium gas mass, metallicity, and temperature. Modeling the star formation rate as...

Observing Baryonic Dark Matter with ALMA (2002)

Kamaya, Hideyuki, Silk, Joseph

It has recently been argued that the unidentified SCUBA objects (USOs) are a thick disk population of free-floating dense, compact galactic gas clumps at a temperature of about 7 K. The...

The Clumpiness of Cold Dark Matter: Implications for the Annihilation Signal (2002)

Taylor, James E., Silk, Joseph

We examine the expected signal from annihilation events in realistic cold dark matter halos. If the WIMP is a neutralino, with an annihilation cross-section predicted in minimal SUSY models for the...

Is the Cosmic Microwave Background Circularly Polarized? (2002)

Cooray, Asantha, Melchiorri, Alessandro, Silk, Joseph

The primordial anisotropies of the cosmic microwave background (CMB) are linearly polarized via Compton-scattering. The Faraday conversion process during the propagation of polarized CMB photons...

Solar Seismic Model as a New Constraint on Supersymmetric Dark Matter (2002)

Lopes, Ilidio, Bertone, Gianfranco, Silk, Joseph

If the Milky Way is populated by WIMPs as predicted by cosmological models of the large-scale structure of the universe and as motivated by SUSY, the capture of high-mass WIMPs by the Sun would...

The Dynamical Evolution of Substructure (2002)

Zhang, Bing, Wyse, Rosemary F. G., Stiavelli, Massimo, Silk, Joseph

The evolution of substructure embedded in non-dissipative dark halos is studied through N-body simulations of isolated systems, both in and out of initial equilibrium, complementing cosmological...

Annihilation Radiation from a Dark Matter Spike at the Galactic Centre (2002)

Bertone, Gianfranco, Sigl, Guenter, Silk, Joseph

We study annihilation radiation of neutralinos in the Galactic centre, assuming the existence of a 'spike' in the dark matter density profile, due to adiabatic accretion onto the massive black hole...

A late-time transition in the cosmic dark energy? (2002)

Bassett, Bruce A., Kunz, Martin, Silk, Joseph, Ungarelli, Carlo

We study constraints from the latest CMB, large scale structure (2dF, Abell/ACO, PSCz) and SN1a data on dark energy models with a sharp transition in their equation of state, w(z). Such a transition...

Forming stars on a viscous time-scale: the key to exponential stellar profiles in disc galaxies? (2002)

Slyz, Adrianne D., Devriendt, Julien E. G., Silk, Joseph, Burkert, Andreas

Solar Neutrinos: Probing the Quasi-Isothermal Solar Core Produced by SUSY Dark Matter Particles (2001)

Lopes, Ilidio, Silk, Joseph

SNO measurements strongly constrain the central temperature of the Sun within a precision of much less than 1%. This result can be used to constrain the parameter space of SUSY dark matter particle...

Aspects of Galaxy Formation (2001)

The implications for helioseismology of experimental uncertainties in Newton's constant (2001)

I describe some of the current challenges in galaxy formation theory with applications to formation of disks and of spheroids. Forthcoming deep surveys of galaxies with Keck and VLT will provide high...

Lopes, Ilidio, Silk, Joseph

The experimental uncertainties in G between different experiments have important implications for helioseismology. We show that these uncertainties for the standard solar model lead to a range in the...

Helioseismology as a New Constraint on SUSY Dark Matter (2001)

Lopes, Ilidio P., Silk, Joseph, Hansen, Steen H.

The presence of dark matter in the solar neighbourhood can be tested in the framework of stellar evolution theory by using the new results of helioseismology. If weakly interacting massive particles...

Combined multi-frequency map for point source substraction (2001)

Naselsky, Pavel, Novikov, Dimitri, Silk, Joseph

A method is proposed for combining multi-frequency maps in order to produce a catalogue of extragalactic point sources using data from future high-precision satellite experiments. We have found the...

The Dark Side of the Universe (2001)

Heating of the intergalactic medium as a result of structure formation (2001)

Most of the matter in the universe is invisible. I review the status of dark matter and describe how both the theory of galaxy formation and novel types of experimental searches are revitalizing...

Nath, Biman B., Silk, Joseph

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Supermassive Black Holes and Galaxy Formation (2001)

Heating of the intergalactic medium due to structure formation (2001)

The formation of supermassive black holes (SMBH) is intimately related to galaxy formation, although precisely how remains a mystery. I speculate that formation of, and feedback from, SMBH may...

Nath, Biman, Silk, Joseph

We estimate the heating of the intergalactic medium due to shocks arising from structure formation. Heating of the gas outside the collapsed regions, with small overdensities (${n_b \over {\bar...

On the Possible Sources of D/H Dispersion at High Redshift (2001)

Fields, Brian D., Olive, Keith A., Silk, Joseph, Casse, Michel, Vangioni-Flam, Elisabeth

Recent observations suggest the existence of a white dwarf population in the Galactic halo, while others suggest that deuterium has been astrated in systems at high redshift and low metallicity. We...

Constraining the window on sterile neutrinos as warm dark matter (2001)

Hansen, Steen H., Lesgourgues, Julien, Pastor, Sergio, Silk, Joseph

Sterile neutrinos may be one of the best Warm Dark Matter candidates we have today. Both lower and upper bounds on the mass of the sterile neutrino come from astronomical observations. We show that...

CO emission from high redshift (2001)

Gnedin, Nickolay Y., Silk, Joseph, Spaans, Marco

Future observations with ALMA will be able to detect star-forming primordial gal axies, and perhaps even their dwarf spheroidal satellites, in CO emission lines at redshifts approaching 10. These...

Merger Histories in Warm Dark Matter Structure Formation Scenario (2001)

Knebe, Alexander, Devriendt, Julien, Mahmood, Asim, Silk, Joseph

Observations on galactic scales seem to be in contradiction with recent high resolution N-body simulations. This so-called cold dark matter (CDM) crisis has been addressed in several ways, ranging...

On the Possibility of Observing H2 Emission from Primordial Molecular Cloud Kernels (2001)

Kamaya, Hideyuki, Silk, Joseph

We study the prospects for observing H$_2$ emission during the assembly of primordial molecular cloud kernels. The primordial molecular cloud cores, which resemble those at the present epoch, can...

Bumpy Power Spectra and Galaxy Clusters (2001)

Knebe, Alexander, Islam, Ranty, Silk, Joseph

The evolution of the abundance of galaxy clusters is not a reliable measure of Omega if there are features on scales of a few Mpc in the primordial power spectrum. Conversely, if we know the...

CMB Constraints on a Baryonic Dark Matter-Dominated Universe (2001)

Griffiths, Louise M, Melchiorri, Alessandro, Silk, Joseph

In recent years, upper limits on the cosmic microwave background (CMB) anisotropies combined with predictions made by theories of galaxy formation, have been extremely powerful in ruling out purely...

Probing Large Distance Higher-Dimensional Gravity with Cosmic Microwave Background Measurements (2001)

Binétruy, Pierre, Silk, Joseph

Star Formation-Regulated Growth of Black Holes in Protogalactic Spheroids (2000)

Burkert, Andreas, Silk, Joseph

The observed relation between central black hole mass and spheroid velocity dispersion is interpreted in terms of a self-regulation model that incorporates a viscous Keplerian accretion disk to feed...

The Formation of Galaxy Disks (2000)

Bumpy Power Spectra and dT/T (2000)

Galaxy disk formation must incorporate the multiphase nature of the interstellar medium. The resulting two-phase structure is generated and maintained by gravitational instability and supernova...

Griffiths, Louise M., Silk, Joseph, Zaroubi, Saleem

With the recent publication of the measurements of the radiation angular power spectrum from the BOOMERanG Antarctic flight (de Bernardis et al. 2000), it has become apparent that the currently...

Star Formation in Viscous Galaxy Disks (2000)

Slyz, Adrianne, Devriendt, Julien, Burkert, Andreas, Prendergast, Kevin, Silk, Joseph

The Lin and Pringle model (1987) of galactic disk formation postulates that if star formation proceeds on the same timescale as the viscous redistribution of mass and angular momentum in disk...

Probing large-distance higher-dimensional gravity with Cosmic Microwave Background measurements (2000)

Binetruy, Pierre, Silk, Joseph

It has been recently argued that higher dimensional gravity theories may manifest themselves not only at short microscopic distances but also at large cosmological scales. We study the constraints...

Amplitude-Phase Analysis of Cosmic Microwave Background maps (2000)

Naselsky, P., Novikov, D., Silk, Joseph

We propose a novel method for the extraction of unresolved point sources from CMB maps. This method is based on the analysis of the phase distribution of the Fourier components for the observed...

An Australia Telescope survey for CMB anisotropies (2000)

Subrahmanyan, Ravi, Kesteven, Michael J., Ekers, Ronald D., Sinclair, M., Silk, Joseph

Restricted Access. An open access version is available at NASA ADS (alternative location).

The Polytropic Equation of State of Interstellar Gas Clouds (2000)

Spaans, Marco, Silk, Joseph

Models are presented for the polytropic equation of state of self-gravitating, quiescent interstellar gas clouds. A detailed analysis, including chemistry, thermal balance, and radiative transfer, is...

Models of Disk Evolution: Confrontation with Observations (2000)

Bouwens, Rychard J., Silk, Joseph

We present simple models for disk evolution based on two different approaches: a forward approach based on predictions generic to hierarchical models for structure formation (e.g., Mo, Mao, & White...

The Cosmic Microwave Background Radiation (2000)

Gawiser, Eric, Silk, Joseph

We summarize the theoretical and observational status of the study of the Cosmic Microwave Background radiation. Its thermodynamic spectrum is a robust prediction of the Hot Big Bang cosmology and...

Dark Matter at the Galactic Center (2000)

Gondolo, Paolo, Silk, Joseph

Particle dark matter near the galactic center is accreted by the central black hole into a dense spike, strongly enhancing its annihilation rate. Searching for its annihilation products may give us...

Dark matter annihilation at the galactic center (1999)

Gondolo, Paolo, Silk, Joseph

If cold dark matter is present at the galactic center, as in current models of the dark halo, it is accreted by the central black hole into a dense spike. Particle dark matter then annihilates...

Constraining Primordial Non-Gaussianity With the Abundance of High Redshift Clusters (1999)

Robinson, James, Gawiser, Eric, Silk, Joseph

We show how observations of the evolution of the galaxy cluster number abundance can be used to constrain primordial non-Gaussianity in the universe. We carry out a maximum likelihood analysis...

Lensing-Induced Structure of Submillimeter Sources: Implications for the Microwave Background (1999)

Scannapieco, Evan, Silk, Joseph, Tan, Jonathan C.

We consider the effect of lensing by galaxy clusters on the angular distribution of submillimeter wavelength objects. While lensing does not change the total flux and number counts of submillimeter...

On the structure and nature of dark matter halos (1999)

Burkert, Andreas, Silk, Joseph

The structure of dark matter halos as predicted from cosmological models is discussed and compared with observed rotation curves of dark matter-dominated dwarf galaxies. The theoretical models...

Seven Paradigms in Structure Formation (1999)

WOMBAT & FORECAST: Making Realistic Maps of the Microwave Sky (1999)

Have we converged on the definitive model of cosmology? I present a critical assessment of the current paradigms for the evolution of large-scale structure.

Jaffe, Andrew H., Gawiser, Eric, Finkbeiner, Douglas, Baker, Joanne C., Balbi, Amedeo, Davis, Marc, ...

The Wavelength-Oriented Microwave Background Analysis Team (WOMBAT) is constructing microwave maps which will be more realistic than previous simulations. Our foreground models represent a...

The Sunyaev-Zel'dovich Effect by Cocoons of Radio Galaxies (1999)

Yamada, Masako, Sugiyama, Naoshi, Silk, Joseph

We estimate the deformation of the cosmic microwave background radiation by the hot region (``cocoon'') around a radio galaxy. A simple model is adopted for cocoon evolution while the jet is on, and...

Event Rate and Einstein Time Evaluation in Pixel Microlensing (1999)

Baltz, Edward A., Silk, Joseph

It has been shown that a flux--weighted full width at half maximum timescale of a microlensing event can be used in an unbiased estimator of the optical depth. For the first time, this allows a...

A Fundamental Test of the Nature of Dark Matter (1999)

Dark matter annihilation at the galactic center (1999)

Dark matter may consist of weakly interacting elementary particles or of macroscopic compact objects. We show that the statistics of the gravitational lensing of high redshift supernovae strongly...

Gondolo, Paolo, Silk, Joseph

Cold dark matter near the galactic center is accreted by the central black hole into a dense spike. Particle dark matter annihilation makes the spike a compact source of photons, electrons,...

Simulating Galaxy Evolution (1998)

Silk, Joseph, Bouwens, Rychard J.

The forwards approach to galaxy formation and evolution is extremely powerful but leaves several questions unanswered. Foremost among these is the origin of disks. A backwards approach is able to...

The WOMBAT Challenge: A "Hounds and Hares" Exercise for Cosmology (1998)

Gawiser, Eric, Finkbeiner, Douglas, Jaffe, Andrew, Baker, Joanne C., Balbi, Amedeo, Davis, Marc, ...

The Wavelength-Oriented Microwave Background Analysis Team (WOMBAT) is constructing microwave skymaps which will be more realistic than previous simulations. Our foreground models represent a...

From the Cosmological Microwave Background to Large-Scale Structure (1998)

Silk, Joseph, Gawiser, Eric

The shape of the primordial fluctuation spectrum is probed by cosmic microwave background fluctuations which measure density fluctuations at z~1000 on scales of hundreds of Mpc and from galaxy...

Detection of Evolved High-Redshift Galaxies in Deep NICMOS/VLT Images (1998)

Benitez, Narciso, Broadhurst, Tom, Bouwens, Rychard, Silk, Joseph, Rosati, Piero

A substantial population of high redshift early-type galaxies is detected in very deep UBVRIJHK images towards the HDF-South. Four elliptical profile galaxies are identified in the redshift range...

A Look At Three Different Scenarios for Bulge Formation (1998)

Bouwens, Rychard J., Cayon, Laura, Silk, Joseph

In this paper, we present three qualitatively different scenarios for bulge formation: a secular evolution model in which bulges form after disks and undergo several central starbursts, a primordial...

Formation of Bulges (1998)

Silk, Joseph, Bouwens, Rychard J.

Bulges, often identified with the spheroidal component of a galaxy, have a complex pedigree. Massive bulges are generally red and old, but lower mass bulges have broader dispersions in color that may...

Temperature Correlations in a Finite Universe (1998)

Scannapieco, Evan, Levin, Janna, Silk, Joseph

We study the effect of a finite topology on the temperature correlations of the cosmic microwave background in a flat universe. Analytic expressions for the angular power spectrum are given for all...

Observational Constraints on Microwave Anisotropy from Point Sources (1998)

Gawiser, Eric, Jaffe, Andrew, Silk, Joseph

Applying basic physical principles to recent observational results, we derive upper and lower limits on microwave anisotropy from point sources over the range of frequencies 10-1000 GHz. We examine...

Cloning Hubble Deep Fields I: A Model-Independent Measurement of Galaxy Evolution (1998)

Bouwens, Rychard J., Broadhurst, Tom, Silk, Joseph

We present a model-independent method of quantifying galaxy evolution in high-resolution images, which we apply to the Hubble Deep Field (HDF). Our procedure is to k-correct all pixels belonging to...

Cloning Hubble Deep Fields II: Models for Evolution by Bright Galaxy Image Transformation (1998)

Bouwens, Rychard J., Broadhurst, Tom, Silk, Joseph

In a companion paper we outlined a methodology for generating parameter-free, model-independent ``no-evolution'' fields of faint galaxy images, demonstrating the need for significant evolution in the...

The Australia telescope search for cosmic microwave background anisotropy (1998)

Subrahmanyan, Ravi, Kesteven, M.J., Ekers, R.D., Sinclair, M., Silk, Joseph

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How the Universe got its Spots (1998)

Levin, Janna, Scannapieco, Evan, De Gasperis, Giancarlo, Silk, Joseph, Barrow, John D.

The universe displays a three-dimensional pattern of hot and cold spots in the radiation remnant from the big bang. The global geometry of the universe can be revealed in the spatial distribution of...

Extracting Primordial Density Fluctuations (1998)

Gawiser, Eric, Silk, Joseph

The combination of detections of anisotropy in the Cosmic Microwave Background radiation and observations of the large-scale distribution of galaxies probes the primordial density fluctuations of the...

Australia Telescope Search for Cosmic Microwave Background Anisotropy (1998)

Subrahmanyan, Ravi, Kesteven, Michael J., Ekers, Ronald D., Sinclair, Malcolm, Silk, Joseph

We have made an 8.7 GHz image of a sky region with a resolution of 8 arcmin and high brightness sensitivity using the Australia Telescope Compact Array (ATCA). in an ultra compact configuration. The...

A Simultaneous Constraint on the Amplitude and Gaussianity of Mass Fluctuations in the Universe (1998)

Robinson, James, Gawiser, Eric, Silk, Joseph

We consider constraints on the amplitude of mass fluctuations in the universe, sigma_8, derived from two simple observations: the present number density of clusters and the amplitude of their...

The topology of the universe: the biggest manifold of them all (1998)

Levin, Janna, Scannapieco, Evan, Silk, Joseph

Clues as to the geometry of the universe are encoded in the cosmic background radiation. Hot and cold spots in the primordial radiation may be randomly distributed in an infinite universe while in a...

Is The Universe Infinite Or Is It Just Really Big? (1998)

Levin, Janna, Scannapieco, Evan, Silk, Joseph

The global geometry of the universe is in principle as observable an attribute as local curvature. Previous studies have established that if the universe is wrapped into a flat hypertorus, the...

Quasars and Galaxy Formation (1998)

Silk, Joseph, Rees, Martin J.

The formation of massive black holes may precede the epoch that characterises the peak of galaxy formation, as characterized by the star formation history in luminous galaxies. Hence protogalactic...

Daniel J. Eisenstein, Wayne Hu, Joseph Silk, Er S. Szalay

We assess the possibility that baryonic acoustic oscillations in adiabatic models may explain the observations of excess power in large-scale structure on 100 h�1 Mpc scales. The observed location...

On Breaking Cosmic Degeneracy (1997)

Can Baryonic Features Produce the Observed 100 Mpc Clustering? (1997)

It has been argued that the power spectrum of the anisotropies in the Cosmic Microwave Background (CMB) may be effectively degenerate, namely that the observable spectrum does not determine a unique...

Eisenstein, Daniel J., Hu, Wayne, Silk, Joseph, Szalay, Alex

We assess the possibility that baryonic acoustic oscillations in adiabatic models may explain the observations of excess power in large-scale structure on 100h^-1 Mpc scales. The observed location...

Cloning Hubble Deep Fields: A Model-Independent Measurement of Galaxy Evolution (1997)

Bouwens, Rychard J., Broadhurst, Tom, Silk, Joseph

We present a model-independent method of quantifying galaxy evolution in high- resolution images, which we apply to the Hubble Deep Field (HDF). Our procedure is to k-correct the pixels belonging to...

Quasar outflows and the formation of dwarf galaxies (1997)

Natarajan, Priyamvada, Sigurdsson, Steinn, Silk, Joseph

We propose a scenario for the formation of a population of baryon-rich, dark matter-deficient dwarf galaxies at high redshift that form from the mass swept out in the Intergalactic Medium (IGM) by...

Inside-Out Infall Formation of Disk Galaxies: Do Predictions Differ from Models without Size Evolution? (1997)

Bouwens, Rychard J., Cayon, Laura, Silk, Joseph

We develop an idealized inside-out formation model for disk galaxies to include a realistic mix of galaxy types and luminosities that provides a fair match to the traditional observables. The...

Molecular Lines as Diagnostics of High Redshift Objects (1997)

Silk, Joseph, Spaans, Marco

Models are presented for CO rotational line emission by high redshift starburst galaxies. The influence of the cosmic microwave background on the thermal balance and the level populations of atomic...

Gravitational Magnification of the Cosmic Microwave Background (1997)

Spectral Features from the Reionization Epoch (1997)

Some aspects of gravitational lensing by large scale structure (LSS) are investigated. We show that lensing causes the damping tail of the cosmic microwave background (CMB) power spectrum to fall...

Baltz, Edward A., Gnedin, Nickolay Y., Silk, Joseph

Emission lines in hydrogen can be used to measure the approximate redshift of the reionization of the universe. This is an important measurement given the lack of a convincing theoretical prediction...

Cumulants as non-Gaussian qualifiers (1997)

Ferreira, Pedro G., Magueijo, Joao, Silk, Joseph

We discuss the requirements of good statistics for quantifying non-Gaussianity in the Cosmic Microwave Background. The importance of rotational invariance and statistical independence is stressed,...

Flat Spots: topological signatures of an open universe in COBE sky maps (1997)

Levin, Janna J., Barrow, John D., Bunn, Emory F., Silk, Joseph

We investigate the behaviour of light rays in an open universe with a partly periodic horn topology. The geodesics can be solved exactly and the periodic topology creates characteristic new effects...

Constraints on a Primordial Magnetic Field (1997)

Barrow, John D., Ferreira, Pedro G., Silk, Joseph

We derive an upper limit of $B_0

A Short History of the Universe (1997)

A Short History of the Universe / J. Silk (1997)

Historia del universo planteada desde las teorías físicas sobre su origen, evolución y futuro. Aplica las teorías de las partículas atómicas para recrear los primeros momentos del Big Bang y...

Can Baryonic Features Produce the Observed 100h -1 Mpc Clustering? (1997)

Historia del universo planteada desde las teorías físicas sobre su origen, evolución y futuro. Aplica las teorías de las partículas atómicas para recrear los primeros momentos del Big Bang y...

Daniel J. Eisenstein, Wayne Hu, Joseph Silk, Alexander S. Szalay

We assess the possibility that baryonic acoustic oscillations in adiabatic models may explain the observations of excess power in large-scale structure on 100h -1 Mpc scales. The observed location...

Peaks in the Cosmic Microwave Background: flat versus open models (1996)

Barreiro, R. B., Sanz, J. L., Martinez-Gonzalez, E., Cayon, L., Silk, Joseph

We present properties of the peaks (maxima) of the CMB anisotropies expected in flat and open CDM models. We obtain analytical expressions of several topological descriptors: mean number of maxima...

Feedback, Disk Self-regulation and Galaxy Formation (1996)

Colors and K-Band Counts of Extremely Faint Field Galaxies (1996)

Self-regulation of star formation in disks is controlled by two dimensionless parameters: the Toomre parameter for gravitational instability and the porosity of the interstellar medium to supernova...

Moustakas, Leonidas A., Davis, Marc, Graham, James R., Silk, Joseph, Peterson, B. A., Yoshii, Y.

We combine deep K-band (Keck) with V- and I-band (NTT) observations of two high-Galactic latitude fields, surveying a total of ~2 sq. arcmin. The K-band galaxy counts continue to rise above K=22,...

Passive Evolution: Are the Faint Blue Galaxy Counts Produced by a Population of Eternally Young Galaxies? (1996)

Bouwens, Rychard J., Silk, Joseph

A constant age population of blue galaxies, postulated in the model of Gronwall & Koo (1995), seems to provide an attractive explanation of the excess of very blue galaxies in the deep galaxy counts....

Angular Sizes of Faint Field Disk Galaxies: Intrinsic Luminosity Evolution (1996)

Cayon, Laura, Silk, Joseph, Charlot, Stephane

In order to explain the small scale-lengths detected in the recent deep field observations performed from large ground-based telescopes and from the Hubble Space Telescope, we investigate the...

How Anisotropic is our Universe? (1996)

Bunn, Emory. F., Ferreira, Pedro, Silk, Joseph

Large-scale cosmic microwave background anisotropies in homogeneous, globally anisotropic cosmologies are investigated. We perform a statistical analysis in which the four-year data from the Cosmic...

The Physics of Microwave Background Anisotropies (1996)

Hu, Wayne, Sugiyama, Naoshi, Silk, Joseph

Cosmic microwave background anisotropies provide a vast amount of cosmological information. Their full physical content and detailed structure can be understood in a simple and intuitive fashion...

How small were the first cosmological objects? (1996)

Tegmark, Max, Silk, Joseph, Rees, Martin, Blanchard, Alain, Abel, Tom, Palla, Francesco

The minimum mass that a virialized gas cloud must have in order to be able to cool in a Hubble time is computed, using a detailed treatment of the chemistry of molecular hydrogen. With a simple model...

CMB radiation power spectrum in CDM open universes up to 2nd order perturbations (1996)

Sanz, Jose L., Martinez-Gonzalez, Enrique, Cayon, Laura, Silk, Joseph, Sugiyama, Naoshi

A second--order perturbation theory approach is developed to calculate temperature anisotropies in the cosmic microwave background. Results are given for open universes and fluctuations corresponding...

On the Effects of Bursts of Massive Star Formation During the Evolution of Elliptical Galaxies (1996)

Zepf, Stephen E., Silk, Joseph

We consider the hypothesis that the formation of elliptical galaxies includes a phase in which star formation is mostly restricted to massive stars, with the bias towards high mass stars increasing...

Baryonic Dark Halos: A Model with MACHOS and Cold Gas Globules (1995)

Gerhard, Ortwin, Silk, Joseph

The dark matter in the halos of galaxies may well be baryonic, and much of the mass within them could be in the form of clusters of substellar objects within which are embedded cold gas globules....

Baryonic Dark Halos: Machos and Cold Gas? (1995)

Gerhard, Ortwin, Silk, Joseph

We consider the possibility that the dark matter in the halos of galaxies may be in the form of clusters of \macho s within which are embedded cold, dense gas clouds. Microlensing experiments have...

Gravitational Microlensing by Clustered MACHOs (1995)

Metcalf, R Benton, Silk, Joseph

It has been proposed that the MACHOs in our galaxy could be clumped in globular cluster--like associations or RAMBOs (robust associations of massive baryonic objects) (Moore \& Silk 1995). Here we...

The Wiener-Filtered COBE DMR Data and Predictions for the Tenerife Experiment (1995)

Bunn, Emory F., Hoffman, Yehuda, Silk, Joseph

We apply a Wiener filter to the two-year COBE DMR data. The resulting sky map has significantly reduced noise levels compared to the raw data: the most prominent hot and cold spots are significant at...

The first generation of stars: first steps towards chemical evolution of galaxies (1995)

Audouze, Jean, Silk, Joseph

We argue that extreme metal-poor stars show a high dispersion in metallicity, because their abundances are the outcome of very few supernova events. Abundance anomalies should appear because of the...

The Physics of Microwave Background Anisotropies (1995)

Hu, Wayne, Sugiyama, Naoshi, Silk, Joseph

Cosmic microwave background anisotropies provide a vast amount of information on both structure formation in the universe and the background dynamics and geometry. The full physical content and...

Dynamical and Observable Constraints on RAMBOs: Robust Associations of Massive Baryonic Objects (1994)

Moore, Ben, Silk, Joseph

If the halo dark matter consists of faint baryonic stars, then these objects probably formed at an early epoch within large associations with similar dynamical properties to globular or open...

The Imprint of $\Omega$ on the Cosmic Microwave Background (1994)

Sugiyama, Naoshi, Silk, Joseph

We investigate the dependence of large angular scale cosmic microwave background anisotropies on various initial conditions, including both adiabatic and isocurvature perturbations and the initial...

Imprints of Galaxy Clsutering Evolution on Delta T / T (1994)

Sanz, Jose L., Silk, Joseph

The nonlinear evolution of matter clustering induces temperature anisotropies in the cosmic microwave background. The fluctuations in temperature are produced at a relatively low redshift, $z\simlt...

Reionization and the Cosmic Microwave Background (1994)