Studies of galaxies in voids

I. observations of Blue Compact Galaxies

¹ Special Astrophysical Observatory RAS, Nizhnij Arkhyz, Karachai-Circassia 369167, Russia
² Isaac Newton Institute of Chile, SAO Branch
³ Observatoire de Paris-Meudon, Meudon, France
⁴ Max-Planck-Institut für Radioastronomie, 53121 Bonn, Germany
⁵ Wise Observatory, Tel-Aviv University, Tel-Aviv 69978, Israel
⁶ Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany

Corresponding author: S. Pustilnik, sap@sao.ru

Received: 7 May 2001
Accepted: 16 April 2002

Abstract

We present here results of studies of the properties of galaxies located in very low density environments. We observed 26 blue compact galaxies (BCGs) from the Second Byurakan (SBS) and Case surveys located in voids with the radial velocities 11 000 km s^-1, two BCGs in the void behind the Virgo cluster and 11 BCGs in denser environments. fluxes and profile widths, as well as estimates of total masses, are presented for the 27 detected galaxies (of which 6 are in three galaxy pairs and are not resolved by the radiotelescope beam). Preliminary comparisons of void BCGs with similar objects from intermediate density regions – in the general field and the Local Supercluster (sub-samples of BCGs in the SBS zone) and in the dense environment of the Virgo Cluster (a BCD sample) – are performed using the hydrogen-to-blue-luminosity ratio /L_B. We find that for the same blue luminosity, for 180, BCGs in lower density environment have on average more . The slope β of the / for BCGs shows a trend of steepening with decreasing bright galaxy density, being very close to zero for the densest environment considered here and reaching β = -0.4 for voids.