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Several observational lines of evidence imply that a fraction of the dark matter in the Galaxy may be comprised of small cold clouds of molecular hydrogen. Such objects are difficult to detect because of their small size and low…

High Energy Astrophysical Phenomena · Physics 2025-01-28 A. V. Popkova , M. S. Pshirkov , A. V. Tuntsov

The concordance model of cosmology and structure formation predicts the formation of isolated very massive stars at high redshifts in dark matter dominated halos of 10^5 to 10^6 Msun. These stars photo-ionize their host primordial molecular…

Astrophysics · Physics 2008-11-26 Tom Abel , John H. Wise , Greg L. Bryan

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 minimum fragmentation scale of a few…

Astrophysics · Physics 2009-07-09 Volker Bromm , Abraham Loeb

We extend the non-equilibrium model for the chemical and thermal evolution of diffuse interstellar gas presented in Richings et al. (2014) to account for shielding from the UV radiation field. We attenuate the photochemical rates by dust…

Astrophysics of Galaxies · Physics 2015-06-19 Alexander J. Richings , Joop Schaye , Benjamin D. Oppenheimer

Optically thin cooling gas at most temperatures above 30K will make condensations by pressure pushing material into cool dense regions. This works without gravity. Cooling condensations will flatten and become planar/similarity solutions.…

Astrophysics · Physics 2009-11-06 D. Lynden-Bell , C. A. Tout

Pristine, atomically-cooled haloes may be the sites of primordial quasar formation because atomic cooling triggers rapid baryon collapse that can create 10$^4$ - 10$^5$ M$_{\odot}$ black hole seeds. However, no numerical simulation has ever…

Astrophysics of Galaxies · Physics 2023-07-19 Samuel J. Patrick , Daniel J. Whalen , Muhammed A. Latif , Jacob S. Elford

In these lecture notes we review the current knowledge about the formation of the first luminous objects. We start from the cosmological context of hierarchical models of structure formation, and discuss the main physical processes which…

Astrophysics · Physics 2015-06-24 Emanuele Ripamonti , Tom Abel

After the recombination of Hydrogen, primordial molecules such as H_2, $HD$ can be formed.The formation of structures in the post-recombination gaseous medium is commonly explained by primordial density fluctuations. In a self-gravitating…

Astrophysics · Physics 2007-05-23 D. Puy , M. Signore

We describe a phenomenological model for molecular hydrogen formation suited for applications in galaxy formation simulations, which includes on-equilibrium formation of molecular hydrogen on dust and approximate treatment of both its…

Astrophysics · Physics 2010-12-28 Nickolay Y. Gnedin , Konstantinos Tassis , Andrey V. Kravtsov

Ultra-luminous infrared galaxies are among the most luminous objects in the local universe and are thought to be powered by intense star formation. It has been shown that in these objects the rotational spectral lines of molecular hydrogen…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Nadia L. Zakamska

In warm dark matter scenarios structure formation is suppressed on small scales with respect to the cold dark matter case, reducing the number of low-mass halos and the fraction of ionized gas at high redshifts and thus, delaying…

Cosmology and Nongalactic Astrophysics · Physics 2018-04-24 Laura Lopez-Honorez , Olga Mena , Sergio Palomares-Ruiz , Pablo Villanueva Domingo

The problem of galaxy formation and its dependence on thermodynamic properties is addressed by using Eulerian hydrodynamic numerical simulations of large scale structure formation. Global galaxy properties are explored in simulations…

Astrophysics · Physics 2009-11-10 J. -M. Alimi , S. Courty

We developed a three-dimensional 2-level hierarchical cosmological code with a realistic and robust treatment of multi-species non-equilibrium ionization and radiative cooling processes, and use it to investigate primordial star forming…

Astrophysics · Physics 2009-10-28 Yu Zhang , Michael L. Norman , Peter Anninos , Tom Abel

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 COBE data. It is found that ionizing uv…

Astrophysics · Physics 2015-06-24 M. Fukugita , M. Kawasaki

We present hydrostatic equilibrium models of spherical, self-gravitating clouds of helium and molecular hydrogen, focusing on the cold, high-density regime where solid- or liquid-hydrogen can form. The resulting structures have masses from…

Astrophysics of Galaxies · Physics 2019-08-21 Mark Walker , Mark Wardle

Radiative cooling is central to a wide range of astrophysical problems. Despite its importance, cooling rates are generally computed using very restrictive assumptions, such as collisional ionization equilibrium and solar relative…

Astrophysics · Physics 2009-01-26 Robert P. C. Wiersma , Joop Schaye , Britton D. Smith

We compare the central mass distribution of galaxies simulated with three different models of the interstellar medium (ISM) with increasing complexity: primordial (H+He) cooling down to 10^4K, additional cooling via metal lines and to lower…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Charlotte Christensen , Fabio Governato , Thomas Quinn , Alyson M. Brooks , David B. Fisher , Sijing Shen , Jacqueline McCleary , James Wadsley

The smallest dark matter haloes are the first objects to form in the hierarchical structure formation of cold dark matter (CDM) cosmology and are expected to be the densest and most fundamental building blocks of CDM structures in our…

Cosmology and Nongalactic Astrophysics · Physics 2016-01-06 Chiamaka Okoli , Niayesh Afshordi

Several lines of evidence suggest that cold, dense gas clouds make a substantial contribution to the total mass of dark halos. If so then physical collisions between clouds must occur; these cause strong, radiative shocks to propagate…

Astrophysics · Physics 2007-05-23 Mark A. Walker

The cooling of baryons in the centers of dark matter halos leads to a more concentrated dark matter distribution. This effect has traditionally been calculated using the model of adiabatic contraction, which assumes spherical symmetry,…

Astrophysics · Physics 2009-11-11 Oleg Y. Gnedin
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