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We investigate the effects of numerous dark matter subhalos in a galaxy-sized halo on the events of strong lensing, to assess their presence as expected from the cold dark matter scenario. Lens galaxies are represented by a smooth ellipsoid…

Astrophysics · Physics 2009-11-07 Masashi Chiba

We argue that, at least a fraction of the newly discovered population of ultra-faint dwarf spheroidal galaxies in the Local Group constitute the fossil relic of a once ubiquitous population of dwarf galaxies formed before reionization with…

Astrophysics · Physics 2011-02-11 Mia S. Bovill , Massimo Ricotti

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

We compare the properties of dwarf galaxies in the Local Group with the simulated galaxies formed before reionization in a cosmological simulation of unprecedented spatial and mass resolution,including radiative feedback effects. We find…

Astrophysics · Physics 2009-11-10 Massimo Ricotti , Nickolay Y. Gnedin

We investigate the effects of the UV background radiation on galaxy formation by using the semi-analytic model including the photoionization process. The semi-analytic model is based on Cole et al. (1994) and we use almost the same…

Astrophysics · Physics 2009-10-30 Masahiro Nagashima , Naoteru Gouda , Norimasa Sugiura

We show that the ionization of dense molecular clouds can be used to set strong constraints on dark matter models producing UV/X-ray photons in their annihilation or decay. We place robust and competitive constraints on various dark matter…

High Energy Physics - Phenomenology · Physics 2026-03-24 Pedro De la Torre Luque , Pierluca Carenza , Thong T. Q. Nguyen

This review deals with the inconsistency of inner dark matter density profiles in dwarf galaxies, known as the cusp-core problem. Particularly, we aim to focus on gas-poor dwarf galaxies. One of the most promising solutions to this cold…

Astrophysics of Galaxies · Physics 2022-01-05 Pierre Boldrini

Self-interacting dark matter was proposed by Spergel & Steinhardt (2000) to alleviate two conflicts between Cold Dark Matter (CDM) models and observations. Firstly, CDM N-body simulations predict dark matter halo density profiles that…

Astrophysics · Physics 2009-11-07 Elena D'Onghia , Andreas Burkert

Cold Dark Matter (CDM) has become the standard modern theory of cosmological structure formation. Its predictions appear to be in good agreement with data on large scales, and it naturally accounts for many properties of galaxies. But…

Astrophysics · Physics 2009-11-07 Joel R. Primack

We review basic properties of the population of dwarf galaxies in the Local Group focusing on dwarf spheroidal galaxies found in the immediate vicinity of the Milky Way. The evidence for dark matter in these objects is critically assessed.…

Cosmology and Nongalactic Astrophysics · Physics 2011-12-05 Ewa L. Lokas

The Cold Dark Matter (CDM) theory predicts a wealth of substructure within dark halos. These predictions match observations of galaxy clusters like the nearby Virgo cluster. However, CDM has a "small scale crisis" since galaxies dominate…

Astrophysics · Physics 2009-11-10 Elena D'Onghia , George Lake

The observed luminosity function (LF) of satellite galaxies shows several interesting features that require a better understanding of gas-thermodynamic processes and feedback effects related to reionization and galaxy formation. In galaxy…

Astrophysics · Physics 2009-11-13 Asantha Cooray , Renyue Cen

Since reionization prevents star formation in most halos below 3 x 10^9 solar masses, dwarf galaxies only populate a fraction of existing dark matter halos. We use hydrodynamic cosmological simulations of the Local Group to study the…

The demographics of dwarf galaxy populations have long been in tension with predictions from the Cold Dark Matter (CDM) paradigm. If primordial density fluctuations were scale-free as predicted, dwarf galaxies should themselves host dark…

Dwarf galaxies are small, dark matter-dominated galaxies, some of which are embedded within the Milky Way. Their lack of baryonic matter (e.g., stars and gas) makes them perfect test beds for probing the properties of dark matter --…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-22 Tri Nguyen , Siddharth Mishra-Sharma , Reuel Williams , Lina Necib

We have developed an accurate, one-dimensional, spherically symmetric, Lagrangian hydrodynamics/gravity code, designed to study the effects of radiative cooling and photo-ionization on the formation of protogalaxies. We examine the ability…

Astrophysics · Physics 2009-10-22 A. A. Thoul

$\Lambda$-Warm Dark Matter (WDM) has been proposed as alternative scenario to $\Lambda$ cold dark matter (CDM), motivated by discrepancies at the scale of dwarf galaxies, with less small-scale power and realized by collisionless particles…

Astrophysics of Galaxies · Physics 2018-08-08 Alice Chau , Lucio Mayer , Fabio Governato

In the cold dark matter model of structure formation, galaxies are assembled hierarchically from mergers and the accretion of subclumps. This process is expected to leave residual substructure in the Galactic dark halo, including partially…

Astrophysics · Physics 2009-11-06 D. Stiff , L. M. Widrow , J. Frieman

Cold Dark Matter (CDM) has become the standard modern theory of cosmological structure formation. Its predictions appear to be in good agreement with data on large scales, and it naturally accounts for many properties of galaxies. But…

Astrophysics · Physics 2007-05-23 Joel R. Primack

To elucidate the permeation of cosmic ultraviolet (UV) background radiation into a pregalactic cloud and subsequent ionization, the frequency-dependent radiative transfer equation is solved, coupled with the ionization process. A spherical…

Astrophysics · Physics 2009-10-30 Yukiko Tajiri , Masayuki Umemura