Discovery of an extremely gas-rich dwarf galaxy triplet with a high
abundance of neutral hydrogen near the center of the Lynx-Cancer void
During the study of a deep sample of galaxies in the nearby Lynx-Cancer void on the Indian GMRT radiotelescope in the HI 21 cm line, we discovered an unusual triplet of dwarf galaxies with a low surface brightness (SDSS J0723+3621, J0723+3622 and J0723+3624) in its central part at a distance of 16 Mpc. Their absolute magnitudes are MB -14.2, -11.9 and -9.7, and the hydrogen mass to luminosity ratios are M(HI)/LB ~3, ~10 and ~25 (in Solar units), respectively. The last two values are among the highest known. Taking into account the blue colors of the galaxies on the images of the Sloan Digital Sky Survey, we estimated the fraction of visible stellar mass to be less than one percent. It is shown that such unusual objects are beyond the detection limits of large redshift surveys in the regions outside the Local Volume and may represent an unknown population of galaxies in the voids.
In collaboration with NCRA, Pune, India
(Contact - S.A.Pustilnik)
Published: MNRAS, 2013, Volume 428, Issue 2, p.1579-1586
Discovery of the cosmological evolution of the characteristics of
the birthplaces of gamma-ray bursts
As a result of the statistical analysis of the characteristics of a sample of gamma-ray bursts with measured redshifts, whose optical light curves have maxima, we have discovered a significant correlation between the maximum luminosities and redshift. The luminosity increases according to a power law with increasing z. This result most probably reflects the cosmological evolution of the interstellar medium density and the star formation rate in the birthplaces of gamma-ray bursts. Thus, we obtained the first ever evidence of a power-law increase of these characteristics with decreasing age of the Universe.
(Contact - G.M.Beskin)