The Environment of HII Galaxies revisited

TL;DR

This study examines the environments of 110 local HII galaxies, analyzing how their proximity to companions influences their properties and the stability of their use in cosmology.

Contribution

It provides a comparative analysis of isolated versus interacting HII galaxies, highlighting environmental effects on their physical characteristics.

Findings

Interacting HII galaxies are more compact and less luminous.

Environmental differences do not impact the L_{Hβ}-σ correlation.

Interacting galaxies have lower velocity dispersions.

Abstract

We present a study of the close (< 200 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 in order 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 verified, these environmental differences do not affect the cosmologically important L_{H{\beta}}-{\sigma} correlation of the HII galaxies.