Deep Near-Infrared Surface Photometry and Properties of Local Volume Dwarf Irregular Galaxies

TL;DR

This study provides deep near-infrared surface photometry of 40 Local Volume dwarf irregular galaxies, revealing their structural properties, color variations, and environmental influences, with implications for galaxy evolution models.

Contribution

It offers the first deep H-band photometry for a significant sample of Local Volume dwarf irregulars, highlighting differences from other surveys and environmental effects on galaxy structure.

Findings

Dwarf irregulars exhibit significant color variation, complicating optical-NIR comparisons.

Many Local Volume dwarfs share structural properties with dwarf ellipticals.

Environmental factors influence the structural scaling relationships of dwarf galaxies.

Abstract

We present deep H-band surface photometry and analysis of 40 Local Volume galaxies, a sample primarily composed of dwarf irregulars in the Cen A group, obtained using the IRIS2 detector at the 3.9m Anglo-Australian Telescope. We probe to a surface brightness of ~25 mag arcsec$^{-2}$, reaching a 40 times lower stellar density than the Two Micron All Sky Survey (2MASS). Employing extremely careful and rigorous cleaning techniques to remove contaminating sources, we perform surface photometry on 33 detected galaxies deriving the observed total magnitude, effective surface brightness and best fitting S\'ersic parameters. We make image quality and surface photometry comparisons to 2MASS and VISTA Hemispheric Survey (VHS) demonstrating that deep targeted surveys are still the most reliable means of obtaining accurate surface photometry. We investigate the B-H colours with respect to mass for Local Volume galaxies, finding that the colours of dwarf irregulars are significantly varied, eliminating the possibility of using optical-NIR colour transformations to facilitate comparison to the more widely available optical data sets. The structure-luminosity relationships are investigated for our `clean' sample of dwarf irregulars. We demonstrate that a significant fraction of the Local Volume dwarf irregular population have underlying structural properties similar to both Local Volume and Virgo Cluster dwarf ellipticals. Linear regressions to structure-luminosity relationships for the Local Volume galaxies and Virgo Cluster dwarf ellipticals show significant differences in both slope and scatter around the established trend lines, suggesting that environment might regulate the structural scaling relationships of dwarf galaxies in comparison to their more isolated counterparts.