Related papers: The HI column density distribution function in fai…
The HIDEEP survey (Minchin et al. 2003) was done in an attempt to find objects having low inferred neutral hydrogen column densities, yet they found a distribution which was strongly peaked at 10^20.65 cm^-2. In an attempt to understand…
{}From deep optical images of three clusters selected by virtue of their X-ray luminosity and/or optical richness (1455+22; $z=0.26$, 0016+16; $z=0.55$ and 1603+43; $z=0.89$), we construct statistically-complete samples of faint field…
There is accumulating evidence that the faint end of the galaxy luminosity function might be very different in different locations. The luminosity function might be rising in rich clusters and flat or declining in regions of low density. If…
We present the results of a study of the amount and distribution of cold atomic gas, as well its correlation with recent star formation in a sample of extremely faint dwarf irregular galaxies. Our sample is drawn from the Faint Irregular…
We have investigated the distribution and evolution of ~3100 intergalactic HI absorbers with HI column densities log N(HI) = [12.75, 17.0] at 1.9 < z < 3.2, using 18 high resolution, high S/N quasar spectra obtained from the ESO VLT/UVES…
Determining the spatial distribution and intrinsic physical properties of neutral hydrogen on cosmological scales is one of the key goals of next-generation radio surveys. We use the EAGLE galaxy formation simulations to assess the…
A recent survey of the Galaxy and M31 reveals that more than 90% of dwarf galaxies within 270 kpc of their host galaxy are deficient in HI gas. At such an extreme radius, the coronal halo gas is an order of magnitude too low to remove HI…
It is known that the gas has a fractal structure in a wide range of spatial scales with a fractal dimension that seems to be a constant around Df = 2.7. It is expected that stars forming from this fractal medium exhibit similar fractal…
Context. Understanding the dwarf galaxy population in low density environments is crucial for testing the LCDM cosmological model. The increase in diversity towards low mass galaxies is seen as an increase in the scatter of scaling…
The Survey of HI in Extremely Low-mass Dwarfs (SHIELD) includes a volumetrically complete sample of 82 gas-rich dwarfs with M_HI~<10^7.2 Msun selected from the ALFALFA survey. We are obtaining extensive follow-up observations of the SHIELD…
We report the discovery of a threshold in the HI column density of Galactic gas clouds below which the formation of the cold phase of HI is inhibited. This threshold is at $N_{HI} = 2 \times 10^{20}$ per cm$^{2}$; sightlines with lower HI…
We present observations and analysis of rotation curves and dark matter halo density profiles in the central regions of four nearby dwarf galaxies. This observing program has been designed to overcome some of the limitations of other…
We study the properties of long gamma-ray burst (GRB) host galaxies using a statistical modelling framework derived to model damped Lyman-$\alpha$ absorbers (DLAs) in quasar spectra at high redshift. The distribution of NHI for GRB-DLAs is…
We present first results of the study of a set of exceptional HI sources identified in the 40% ALFALFA extragalactic HI survey catalog alpha.40 as being both HI massive (M_HI > 10^10 Msun) and having high gas fractions for their stellar…
Luminosity Functions have been obtained for very faint dwarf galaxies in the cores of four rich clusters of galaxies (Abell 2052, 2107, 2199 and 2666). It is found that the luminosity function of dwarf galaxies rises very steeply in these…
We compare the cumulative star formation histories (SFHs) of Local Group (LG) dwarf galaxies with those in the volume-limited ACS Nearby Galaxy Survey Treasury (ANGST) sample (D < 4 Mpc), in order to understand how typical the LG dwarf…
We present Halpha rotation curves for a sample of 15 dwarf and LSB galaxies. From these, we derive limits on the slopes of the central mass distributions. Assuming the density distributions of dark matter halos follow a power-law at small…
We use state-of-the-art cosmological zoom simulations to explore the distribution of neutral gas in and around galaxies that gives rise to high column density \ion{H}{i} \mbox{Ly-$\alpha$} absorption (formally, sub-DLAs and DLAs) in the…
We present the first estimate, based on direct HI 21 cm observations, of the HI mass function (HIMF) of star-forming galaxies at $z\approx1$, obtained by combining our measurement of the scaling relation between HI mass ($M_{HI}$) and…
The formation mechanism of high-concentration dwarf galaxies is still a mystery. We perform a comparative study of the intrinsic shape of nearby low-mass galaxies with different stellar concentration. The intrinsic shape is parameterized by…