Using analytic arguments and a suite of very high resolution (∼ 10 M⊙ per particle) cosmological hydro-dynamical simulations, we argue that high redshift, z ∼ 10, M ∼ 10 M⊙ halos, form the smallest ‘baryonic building block’ (BBB) for galaxy formation. These halos are just massive enough to efficiently form stars through atomic line cooling and to hold onto their gas in the presence of supernova...

We have begun a compilation of H i maps of peculiar galaxies kindly contributed by individual investigators, many as part of the “Gas & Galaxy Evolution” conference. In this gallery we present images of the first ∼180 objects, which includes over 400 individually cataloged galaxies. The images consist of a greyscale representation of the optical morphology and an accompanying optical image with...

We present deep JHK images of I Zw 18, the most metal-deficient Blue Compact Dwarf (BCD) galaxy known, and analyze them in conjunction with archival HST/WFPC2 optical images. To investigate the stellar populations, we have divided the main body of I Zw18 into eight regions, and fit the optical, near-infrared (NIR), and hybrid optical-NIR colors of these and the C component with evolutionary syn...

We compare the characteristics of stellar populations with those of dark halos. Dark matter around galaxies, and in groups, clusters and voids is discussed. Modern data suggest that the overall density of matter in the Universe is ΩM = 0.3 ± 0.1, about 80 % of this matter is nonbaryonic dark matter, and about 20 % is baryonic, mostly in the form of hot intra-cluster and intragroup gas, the rest...

We study the evolution of globular cluster systems (GCS) in elliptical galaxies and explore the dependence of their main properties on the mass and the size of the host galaxy. We have focussed our attention on the evolution of the GCS mass function (GCMF), on the fraction of surviving clusters and on the ratio of the final to initial total mass in clusters; the dependence of these GCS properti...

It was suggested that some of the short-duration Gamma-Ray Bursts (GRB) are giant flares of Soft Gammaray Repeaters (SGR) in nearby galaxies. To test this hypothesis, I have constructed a sample of 47 short GRBs, detected by the Inter-Planetary Network (IPN), for which the position is constrained by at least one annulus on the celestial sphere. For each burst, I have checked whether its IPN 3-σ...

In this short report, I briefly review and illustrate different techniques used to derive mass (hence M/L) profiles of individual galaxies.

We present VLA H i 21 cm observations of HIJASS J1021 6842, which has been discovered in the direction of the M81 Group. Our synthesis imaging reveals that the H i is distributed over a larger angular extent and velocity range than the single-dish discovery observations. Assuming that HIJASS J1021 6842 is at the distance of the M81 Group, we detect M, of H i distributed over as much as 30 kpc, ...

The Angstrom Project is using a distributed network of two-meter class telescopes to conduct a high cadence pixel-lensing survey of the bulge of the Andromeda Galaxy (M31). With the expansion of global telescope network, the detection efficiency of pixel-lensing surveys is rapidly improving. In this paper, we estimate the detection rate of binary lens events expected from high-cadence pixel-len...

We present results from an Andromeda Galaxy (M31) survey of star-forming regions based on 24 μm luminosity for H2O masers, NH3(1,1) and NH3(2,2) lines, and Hydrogen recombination lines (H66α). Although five H2O masers were detected in the initial survey of 206 regions towards M31, we do not detect additional masers in a follow up survey of 300 similar luminous 24 μm regions. We do not detect NH...