Igor Karachentsev (Special Astrophysical Observatory, Russian Academy of Sciences)

Low density structures in the Local Universe
When Apr 26, 2013 from 10:30 AM to 12:00 PM
  • Colloquium
Where SH, Lecture hall
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We present results of our search for low-density associations of galaxies, as well as empty volumes in the Local Supercluster and its vicinity ( D < 45 Mpc). By percolation method we found 226 diffuse, non-virialized agglomerates with n>3 members. Eight the most populated among them ( n > 25) have following median parameters: linear size of ~6 Mpc, radial velocity dispersion of 170 km/s, virial mass-to-stellar mass ratio ~ 700 and a density contrast ~5.

In the same volume, we also found 89 spherical cosmic voids having diameters from 12 to 24 Mpc.

About 93% of them are overlapping, and form three hyper-voids. The largest one contains 56 initial spherical cells and extends in a horseshoe shape, enveloping the Local Volume and the Virgo cluster.

A scarce population of the local voids are represented by dwarf late-type galaxies with a high gas content and moderate star formation rates. Most of them sit shallow near the surfaces of cosmic voids.

You can download the talk here (pdf, 2 MB).