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3D structure of nearby groups of galaxies

Published online by Cambridge University Press:  12 October 2016

L. Makarova
Affiliation:
Special Astrophysical Observatory, Nizhniy Arkhyz, Karachai-Cherkessia 369167, Russia email: lidia@sao.ru
D. Makarov
Affiliation:
Special Astrophysical Observatory, Nizhniy Arkhyz, Karachai-Cherkessia 369167, Russia email: lidia@sao.ru
A. Klypin
Affiliation:
Astronomy Department, New Mexico State University, MSC 4500, P.O.Box 30001, Las Cruces, NM, 880003-8001, USA
S. Gottlöber
Affiliation:
Leibniz-Institut für Astrophysik (AIP), An der Sternwarte 16, D-14482 Potsdam, Germany
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Abstract

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Using high accuracy distance estimates, we study the three-dimensional distribution of galaxies in five galaxy groups at a distance less than 5 Mpc from the Milky Way. Due to proximity of these groups our sample of galaxies is nearly complete down to extremely small dwarf galaxies with absolute magnitudes MB = -12. We find that the average number-density profile of the groups shows a steep power-law decline dn/dV ∼ R-3 at distances R=(100–500) kpc consistent with predictions of the standard cosmological model. We also find that there is no indication of a truncation or a cutoff in the density at the expected virial radius: the density profile extends at least to 1.5 Mpc. Vast majority of galaxies within 1.5 Mpc radius around group centres are gas-rich star-forming galaxies. Early-type galaxies are found only in the central ∼ 300 kpc region. Lack of dwarf spheroidal and dwarf elliptical galaxies in the field and in the outskirts of large groups is a clear indication that these galaxies experienced morphological transformation when they came close to the central region of forming galaxy group.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2016