How Small Were the First Cosmological Objects?

  title={How Small Were the First Cosmological Objects?},
  author={Max Tegmark and Joseph I. Silk and Martin J. Rees and Alain Blanchard and Tom Abel and Francesco Palla},
  journal={The Astrophysical Journal},
  pages={1 - 12}
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 for halo profiles, we reduce the problem to that of numerically integrating a system of chemical equations. The results agree well with numerically expensive three-dimensional simulations, and our approach has the advantage of being able to explore large regions of parameter space rapidly. The… 

How big were the first cosmological objects

We calculate the cooling times at constant density for haloes with virial temperatures from 100 K to 1 × 105 K that originate from a 3σfluctuation of a CDM power spectrum in three different


We perform a suite of cosmological simulations in the ΛCDM paradigm of the formation of the first structures in the universe prior to astrophysical reheating and reionization (15 ≲ z < 200). These

Was Star Formation Suppressed in High-Redshift Minihalos?

The primordial gas in the earliest dark matter halos, collapsing at redshifts z ~ 20, with masses Mhalo ~ 106 M☉ and virial temperatures Tvir < 104 K, relied on the presence of molecules for cooling.

Formation of Primordial Stars in a ΛCDM Universe

We study the formation of the first generation of stars in the standard cold dark matter model. We use a very high resolution cosmological hydrodynamic simulation that achieves a dynamic range of

The first generation of star-forming haloes

We model gas cooling in high-resolution N-body simulations in order to investigate the formation of the first generation of stars. We follow a region of a Lambda cold dark matter (�CDM) universe

Simulation of Primordial Object Formation

We have included the chemical rate network responsible for the formation of molecular hydrogen in the N-body hydrodynamic code, HYDRA, in order to study the formation of the first cosmological

Low-temperature primordial gas in merging halos

The thermal regime of the baryons behind shock waves arising in the process of virialization of dark matter halos is governed at certain conditions by radiation of HD lines. A small fraction of the

Simulations of Early Structure Formation: Primordial Gas Clouds

We use cosmological simulations to study the origin of primordial star-forming clouds in a ΛCDM universe, by following the formation of dark matter halos and the cooling of gas within them. To model


Recently, Tseliakhovich & Hirata showed that during the cosmic Dark Ages the baryons were typically moving supersonically with respect to the dark matter with a spatially variable Mach number. Such

The Fate of the First Galaxies. I. Self-consistent Cosmological Simulations with Radiative Transfer

In cold dark matter (CDM) cosmogonies, low-mass objects play an important role in the evolution of the universe. Not only are they the first luminous objects to shed light in a previously dark



Cosmological Formation of Low-Mass Objects

We investigate the early formation of bound objects with masses comparable to the cosmological Jeans mass (10^5 solar masses). We follow the growth of isolated spherically symmetric density peaks

Hydrogen Molecules and the Radiative Cooling of Pregalactic Shocks II: Low Velocity Shocks at High Redshift

Detailed results for the hydrodynamical, thermal, ionization, and molecular formation history of postshock cooling flows behind steady state shocks in a primordial gas at redshifts z = 5, 10, and 20

Reionization during hierarchical clustering in a universe dominated by cold dark matter

We investigate reheating of the universe by early formation of stars and quasars in the hierarchical clustering scheme of cold dark matter scenario, with perturbation fluctuations normalized by the

Reionization and small-scale fluctuations in the microwave background

It is shown that electron scattering off the moving ionized medium can regenerate arcminute fluctuations in almost all models of galaxy formation. Explicit calculations are presented for

The collisionless damping of density fluctuations in an expanding universe

The best candidate for the dark matter is a massive collisionless non-baryonic relic of the early universe. The most natural type of initial density fluctuations expected are of the adiabatic rather

A hydrodynamic approach to cosmology: the primeval baryon isocurvature model

The primeval baryon isocurvature (PBI) model for the origin of cosmological structure is explored with the aid of detailed numerical simulations. In this model we assume there is no exotic dark

A recipe for galaxy formation

We present a detailed prescription for how galaxy formation can be modelled in hierarchical theories of structure formation. Our model incorporates the formation and merging of dark matter halos, the

The physics of dissipational galaxy formation.

A number of arguments lead one to consider the possibility that the first massive galaxies were formed after redshift 10. The formation of galaxies at small redshifts can only have occurred if the

Reionization and cosmic microwave background distortions: A complete treatment of second-order Compton scattering.

  • HuScottSilk
  • Physics
    Physical review. D, Particles and fields
  • 1994
A complete treatment of Compton scattering to second order is considered, an approach which may be applicable to other astrophysical situations, and new constraints on baryonic dark matter models are set.

On the fragmentation of cosmic gas clouds. I. The formation of galaxies and the first generation of stars.

The formation of galaxies is studied in the context of the fragmentation of massive diffuse ionized gas clouds. A semiquantitative discussion of the role of cooling indicates that there is a