Related papers: Dwarf Galaxy Formation Was Suppressed By Cosmic Re…
Properties of nearby dwarf galaxies are briefly discussed. Dwarf galaxies vary widely in their star formation histories, the ages of their subpopulations, and in their enrichment history. Furthermore, many dwarf galaxies show evidence for…
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…
We consider the early stages of cosmic hydrogen or helium reionization, when ionizing sources were still rare. We show that Poisson fluctuations in the galaxy distribution substantially affected the early bubble size distribution, although…
The existence of massive ($10^{11}$ solar masses) elliptical galaxies by redshift z~4 (when the Universe was 1.5 billion years old) necessitates the presence of galaxies with star-formation rates exceeding 100 solar masses per year at z>6…
Reionizing the Universe with galaxies appears to require significant star formation in low-mass halos at early times, while local dwarf galaxy counts tell us that star formation has been minimal in small halos around us today. Using simple…
In the standard cosmological model, dark matter drives the structure formation and constructs potential wells within which galaxies may form. The baryon fraction in dark halos can reach the universal value (15.7%) in massive clusters and…
The first generation of stars were born a few hundred million years after the big bang. These stars synthesized elements heavier than H and He, that are later expelled into the interstellar medium, initiating the rise of metals. Within this…
The dividing line between galaxies that are quenched by reionization ("relics") and galaxies that survive reionization (i.e. continue forming stars) is commonly discussed in terms of a halo mass threshold. We probe this threshold in a…
We study the sizes of galaxies in the Epoch of Reionization using a sample of ~100,000 galaxies from the BlueTides cosmological hydrodynamical simulation from z=7 to 11. We measure the galaxy sizes from stellar mass and luminosity maps,…
In this paper the counts and colors of the faint galaxies observed in the Hubble Deep Field are fitted by means of simple luminosity evolution models which incorporate a numerous population of fading dwarfs. The observed color distribution…
There appears to exist a conflict between the standard structure formation theory and the existence of the faint dwarf spheroidal galaxies in the Local Group. Theoretical considerations suggest that a cold dark matter universe has been a…
We develop a coupled model for the evolution of the global properties of the intergalactic medium (IGM) and the formation of galaxies, in the presence of a photoionizing background due to stars and quasars. We use this model to predict the…
We present a large sample of candidate galaxies at z~7--10, selected in the HUDF using the new observations made by the HST/WFC3. Our sample is composed of 20 z-dropouts, 15 Y-dropouts, and 20 J-dropouts. The surface densities of the…
The sources that reionized the universe are still unknown, but likely candidates are faint but numerous galaxies. In this paper we present results from running a high resolution, uniform volume simulation, the Vulcan, to predict the number…
Low-mass dwarf galaxies ($M_{\rm vir} \lesssim 10^9\rm\ M_\odot$) are fundamental cosmological building blocks, yet the physical processes driving their structural diversity remain poorly understood. Recent numerical simulations have…
Star formation in half of massive galaxies was quenched by the time the Universe was three billion years old. Very low amounts of molecular gas appear responsible for this, at least in some cases, though morphological gas stabilization,…
Dwarf spheroidal satellite galaxies have emerged a powerful probe of small-scale dark matter clustering and of cosmic reionization. They exhibit structural and chemical continuity with dwarf irregular galaxies in the field and with…
We study the observed cosmic ionizing background as a constraint on the nature of the sources responsible for the reionization of the Universe. In earlier work, we showed that extrapolations of the Ultra-Violet Luminosity Function (LF) of…
Low-mass dwarf galaxies are very sensitive test-beds for theories of cosmic structure formation since their weak gravitational fields allow the effects of the relevant physical processes to clearly stand out. Up to now, no unified account…
Observations of the Epoch of Reionization (EoR) have the potential to answer long-standing questions of astrophysical interest regarding the nature of the first luminous sources and their effects on the intergalactic medium (IGM). We…