Igor Karachentsev (SAO, Russian Academy of Sciences)

Mining the Local Volume - Igor Karachentsev colloquium

ATNF Marsfield Lecture Theatre

Abstract

After recent systematic optical, IR, and HI surveys, the total
number of known galaxies within 10 Mpc increased from 179 to 550.
About half this Local Volume (LV) sample is now imaged with HST,
yielding the galaxy distances with accuracy ~8% . For the majority
of the LV galaxies we currently have H-alpha fluxes that allow us to
reconstruct the star formation history of our neighbourhood. For
the late-type LV galaxies their HI masses and angular momentum follow
the linear relation in the range of 4 orders that are expected
for rotating gaseous disks being near the gravitational instability
threshold. The data obtained on the LV galaxies imply important
cosmological parameters, in particular, the mean local matter density
and HI mass density, as well as SFR density. Surprisingly,
the local Hubble flow around the LV groups is very calm, with 1D rms
deviations of 25 km/s that is a signature of the Universe
vacuum-dominated on small scales. The cold infall pattern around nearby
groups provides us with a new method to determine the
total mass of the groups independent from virial mass estimates.