The environment of HII galaxies revisited

¹ Institute for Astronomy & Astrophysics, Space Applications & Remote Sensing, National Observatory of Athens, Palaia Penteli, 15236 Athens, Greece
e-mail: ekoulour@noa.gr
² Physics Department of Aristotle University of Thessaloniki, University Campus, 54124 Thessaloniki, Greece
³ Instituto Nacional de Astrofísica Optica y Electrónica, CP 72840 Puebla, Mexico
⁴ Institute of Astronomy, University of Cambridge, Madingley Rd, CB3 OHA, Cambridge
⁵ Institute for Astronomy of the University of Hawaii, 2680 Woodlawn Drive, 96822 Honolulu, HI, USA
⁶ Academy of Athens Research Center for Astronomy & Applied Mathematics, Soranou Efessiou 4, 11-527 Athens, Greece

Received: 14 December 2012
Accepted: 26 March 2013

Abstract

We present a study of the close (≲ 200 h₇₅^-1 kpc) environment of 110 relatively local (z ≲ 0.16) HII galaxies, selected from the Sloan Digital Sky Survey (SDSS; DR7). We use available spectroscopic and photometric redshifts to investigate the presence of a close and possibly interacting companion galaxy. Our aim is to compare the physical properties of isolated and interacting HII galaxies and investigate possible systematic effects in their use as cosmological probes. We find that interacting HII galaxies tend to be more compact, less luminous and have a lower velocity dispersion than isolated ones, in agreement with previous studies on smaller samples. However, as we verify, these environmental differences do not affect the cosmologically important L_Hβ − σ correlation of the HII galaxies.