Volker Bromm

The observational signature of the first H II regions (2009)

Greif, Thomas H., Johnson, Jarrett L., Klessen, Ralf S., Bromm, Volker

We use three-dimensional smoothed particle hydrodynamics simulations together with a dynamical ray-tracing scheme to investigate the build-up of the first H ii regions around massive Population III...

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....

First Light Sources at the End of the Dark Ages: Direct Observations of Population III Stars, Proto-Galaxies, and Supernovae During the Reionization Epoch (2009)

Cooke, Jeff, Cooray, Asantha, Chary, Ranga-Ram, Bromm, Volker, Cen, Renyue, Ellis, Richard, ...

The cosmic dark ages are the mysterious epoch during which the pristine gas began to condense and ultimately form the first stars. Although these beginnings have long been a topic of theoretical...

The First Galaxies: Signatures of the Initial Starburst (2009)

Johnson, Jarrett L., Greif, Thomas H., Bromm, Volker, Klessen, Ralf S., Ippolito, Joseph

Detection of the radiation emitted from the first galaxies at z > 10 will be made possible in the next decade, with the launch of the James Webb Space Telescope (JWST). We carry out cosmological...

A New Era in Extragalactic Background Light Measurements: The Cosmic History of Accretion, Nucleosynthesis and Reionization (2009)

Cooray, Asantha, Amblard, Alexandre, Beichman, Charles, Benford, Dominic, Bernstein, Rebecca, Bock, James, ...

(Brief Summary) What is the total radiative content of the Universe since the epoch of recombination? The extragalactic background light (EBL) spectrum captures the redshifted energy released from...

Accretion onto Intermediate-Mass Black Holes in Dense Protogalactic Clouds (2008)

Milosavljevic, Milos, Couch, Sean M., Bromm, Volker

We present the first results from two-dimensional simulations of radiatively-efficient accretion of metal-free gas onto intermediate-mass black holes. We fix the shape of the spectral energy...

The minimum stellar metallicity observable in the Galaxy (2008)

Frebel, Anna, Johnson, Jarrett L., Bromm, Volker

The first stars fundamentally transformed the early Universe through their production of energetic radiation and the first heavy chemical elements. The impact on cosmic evolution sensitively depends...

Accretion onto Seed Black Holes in the First Galaxies (2008)

Milosavljevic, Milos, Bromm, Volker, Couch, Sean M., Oh, S. Peng

The validity of the hypothesis that the massive black holes in high redshift quasars grew from stellar-sized "seeds" is contingent on a seed's ability to double its mass every few ten million years....

Chemical mixing in smoothed particle hydrodynamics simulations (2008)

Greif, Thomas H., Glover, Simon C. O., Bromm, Volker, Klessen, Ralf S.

We introduce a simple and efficient algorithm for diffusion in smoothed particle hydrodynamics (SPH) simulations and apply it to the problem of chemical mixing. Based on the concept of turbulent...

Visualization of Cosmological Particle-Based Datasets (2008)

Paul Arthur, Navrátil Student Member, Jarrett L. Johnson, Volker Bromm

Abstract—We describe our visualization process for a particle-based simulation of the formation of the first stars and their impact on cosmic history. The dataset consists of several hundred...

The First Galaxies: Assembly, Cooling and the Onset of Turbulence (2008)

Greif, Thomas H., Johnson, Jarrett L., Klessen, Ralf S., Bromm, Volker

We investigate the properties of the first galaxies at z > 10 with highly resolved numerical simulations, starting from cosmological initial conditions and taking into account all relevant primordial...

The First Stars (2008)

Johnson, Jarrett L., Greif, Thomas H., Bromm, Volker

The formation of the first generations of stars at redshifts z > 15-20 signaled the transition from the simple initial state of the universe to one of increasing complexity. We here review recent...

Occurrence of Metal-free Galaxies in the Early Universe (2007)

Johnson, Jarrett L., Greif, Thomas H., Bromm, Volker

The character of the first galaxies at redshifts z > 10 strongly depends on their level of pre-enrichment, which is in turn determined by the rate of primordial star formation prior to their...

Uncovering the Chemical Signature of the First Stars in the Universe (2007)

Karlsson, Torgny, Johnson, Jarrett L., Bromm, Volker

The chemical abundance patterns observed in metal-poor Galactic halo stars contain the signature of the first supernovae, and thus allows us to probe the first stars that formed in the universe. We...

Towards the First Galaxies (2007)

Greif, Thomas H., Johnson, Jarrett L., Bromm, Volker

The formation of the first galaxies at redshifts z~10-15 signaled the transition from the simple initial state of the universe to one of ever increasing complexity. We here review recent progress in...

GRB Cosmology (2007)

Bromm, Volker, Loeb, Abraham

Current observations are about to open up a direct window into the final frontier of cosmology: the first billion years in cosmic history when the first stars and galaxies formed. Even before the...

Impact of Cosmic Rays on Population III Star Formation (2007)

Stacy, Athena, Bromm, Volker

We explore the implications of a possible cosmic ray (CR) background generated during the first supernova explosions that end the brief lives of massive Population III stars. We show that such a CR...

The First Supernova Explosions: Energetics, Feedback, and Chemical Enrichment (2007)

Greif, Thomas H., Johnson, Jarrett L., Bromm, Volker, Klessen, Ralf S.

We perform three-dimensional smoothed particle hydrodynamics simulations in a realistic cosmological setting to investigate the expansion, feedback, and chemical enrichment properties of a 200 M_sun...

Probing the Formation of the First Low-Mass Stars with Stellar Archaeology (2007)

Frebel, Anna, Johnson, Jarrett L., Bromm, Volker

We investigate the conditions under which the first low-mass stars formed in the universe by confronting theoretical predictions governing the transition from massive Population III to low-mass...

Local radiative feedback in the formation of the first protogalaxies (2006)

Johnson, Jarrett L., Greif, Thomas H., Bromm, Volker

The formation of the first galaxies is influenced by the radiative feedback from the first generations of stars. This feedback is manisfested by the heating and ionization of the gas which lies...

The aftermath of the first stars: massive black holes (2006)

Johnson, Jarrett L., Bromm, Volker

We investigate the evolution of the primordial gas surrounding the first massive black holes formed by the collapse of Population III stars at redshifts z > 20. Carrying out three-dimensional...

Two populations of metal-free stars in the early Universe (2006)

Greif, Thomas H., Bromm, Volker

We construct star formation histories at redshifts z > 5 for two physically distinct populations of primordial, metal-free stars, motivated by theoretical and observational arguments that have hinted...

GRB Cosmology and the First Stars (2006)

Bromm, Volker, Loeb, Abraham

Gamma-Ray Bursts (GRBs) are unique probes of the cosmic star formation history and the state of the intergalactic medium up to the redshifts of the first stars. In particular, the ongoing {\it Swift}...

Formation of the First Stars (2005)

Bromm, Volker

How and when did the first generation of stars form at the end of the cosmic dark ages? Quite generically, within variants of the cold dark matter model of cosmological structure formation, the first...

High-Redshift Gamma-Ray Bursts from Population III Progenitors (2005)

Bromm, Volker, Loeb, Abraham

Detection of gamma-ray bursts (GRBs) from redshifts z > 7 would open a new window into the earliest epoch of cosmic star formation. We construct separate star formation histories at high redshifts...

The H II Region of the First Star (2005)

Alvarez, Marcelo A., Bromm, Volker, Shapiro, Paul R.

Simulations predict that the first stars in an LCDM universe formed at redshifts z>20 in minihalos with masses of about 10^6 M_sun. We have studied their radiative feedback by simulating the...

The cooling of shock-compressed primordial gas (2005)

Johnson, Jarrett L., Bromm, Volker

We find that at redshifts z > 10, HD line cooling allows strongly-shocked primordial gas to cool to the temperature of the cosmic microwave background (CMB). This temperature is the minimum value...

Accretion onto a Primordial Protostar (2003)

Bromm, Volker, Loeb, Abraham

We present a three-dimensional numerical simulation that resolves the formation process of a Population III star down to a scale of ~100 AU. The simulation is initialized on the scale of a dark...

Cosmic Renaissance: The First Sources of Light (2003)

Bromm, Volker

I review recent progress in understanding the formation of the first stars and quasars. The initial conditions for their emergence are given by the now firmly established model of cosmological...

The First Stars (2003)

Bromm, Volker, Larson, Richard B.

We review recent theoretical results on the formation of the first stars in the universe, and emphasize related open questions. In particular, we discuss the initial conditions for Population III...

The Formation of the First Low-Mass Stars From Gas With Low Carbon and Oxygen Abundances (2003)

Bromm, Volker, Loeb, Abraham

The first stars in the Universe are predicted to have been much more massive than the Sun. Gravitational condensation accompanied by cooling of the primordial gas due to molecular hydrogen, yields a...

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...

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 characteristic stellar mass as a function of redshift (2003)

Clarke, Cathie J., Bromm, Volker

We present a model for the star formation process during the initial collapse of dark matter haloes at redshifts z=0-30. We derive a simple expression for the characteristic stellar mass scale during...

The First Sources of Light (2003)

Bromm, Volker, Loeb, Abraham

We review recent theoretical results on the formation of the first stars and quasars in the universe, and emphasize related open questions. In particular, we list important differences between the...

Death in the dark ages: the first supernova explosions in the universe Elektronische Daten (2003)

Bromm, Volker, 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

Formation of the First Supermassive Black Holes (2002)

Bromm, Volker, Loeb, Abraham

We consider the physical conditions under which supermassive black holes could have formed inside the first galaxies. Our SPH simulations indicate that metal-free galaxies with a virial temperature...

The Formation of Close Binary Systems by Dynamical Interactions and Orbital Decay (2002)

Bate, Matthew R., Bonnell, Ian A., Bromm, Volker

We present results from the first hydrodynamical star formation calculation to demonstrate that close binary stellar systems (separations $\lsim 10$ AU) need not be formed directly by fragmentation....

The Formation of a Star Cluster: Predicting the Properties of Stars and Brown Dwarfs (2002)

Bate, Matthew R., Bonnell, Ian A., Bromm, Volker

We present results from the largest numerical simulation of star formation to resolve the fragmentation process down to the opacity limit. The simulation follows the collapse and fragmentation of 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...

The Formation Mechanism of Brown Dwarfs (2002)

Bate, Matthew R., Bonnell, Ian A., Bromm, Volker

We present results from the first hydrodynamical star formation calculation to demonstrate that brown dwarfs are a natural and frequent product of the collapse and fragmentation of a turbulent...

The Expected Redshift Distribution of Gamma-Ray Bursts (2002)

Bromm, Volker, Loeb, Abraham

We predict the redshift distribution of Gamma-Ray Bursts (GRBs) assuming that they trace the cosmic star formation history. We find that a fraction >~50% of all GRBs on the sky originate at a...

The Formation of the First Globular Clusters in Dwarf Galaxies Before the Epoch of Reionization (2002)

Bromm, Volker, Clarke, Cathie J.

We explore a mechanism for the formation of the first globular clusters, operating during the assembly of dwarf galaxies at high redshifts, z > 10. The substructure in the dark matter and the...

The Contribution of the First Stars to the Cosmic Infrared Background (2001)

Santos, Michael R., Bromm, Volker, Kamionkowski, Marc

We calculate the contribution to the cosmic infrared background from very massive metal-free stars at high redshift. We explore two plausible star-formation models and two limiting cases for the...

From Darkness To Light: The First Stars in the Universe (2001)

Bromm, Volker, Coppi, Paolo S., Larson, Richard B.

Paramount among the processes that ended the cosmic `dark ages' must have been the formation of the first generation of stars (the so-called Population III). We summarize recent progress in...

The Formation of the First Stars. I. The Primordial Star Forming Cloud (2001)

Bromm, Volker, Coppi, Paolo S., Larson, Richard B.

To constrain the nature of the very first stars, we investigate the collapse and fragmentation of primordial, metal-free gas clouds. We explore the physics of primordial star formation by means of...

Generic Spectrum and Ionization Efficiency of a Heavy Initial Mass Function for the First Stars (2000)

Bromm, Volker, Kudritzki, Rolf P., Loeb, Abraham

We calculate the generic spectral signature of an early population of massive stars at high redshifts. For metal-free stars in the mass range of 100-1000 solar masses, we find that the combined...

Forming the First Stars in the Universe: The Fragmentation of Primordial Gas (1999)

Bromm, Volker, Coppi, Paolo S., Larson, Richard B.

In order to constrain the initial mass function (IMF) of the first generation of stars (Population III), we investigate the fragmentation properties of metal-free gas in the context of a hierarchical...

The Spectrum of GRB 930131 (``Superbowl Burst'') from 20 keV to 200 MeV (1999)

Bromm, Volker, Schaefer, Bradley E.

We have constructed a broad-band spectrum for GRB 930131 (the ``Superbowl Burst''), ranging from 20 keV to 200 MeV, by combining spectral information from the Gamma Ray Observatory's BATSE, COMPTEL...

Do Small-Scale Dark Matter Fluctuations Govern the Fragmentation of Primordial Gas? (1998)

Bromm, Volker, Coppi, Paolo, Larson, Richard

In order to constrain the initial mass function of the first generation of stars (Population III), one has to study the fragmentation properties of primordial gas. We present results from 3D...