Deep near-infrared surface photometry and properties of Local Volume dwarf irregular galaxies

T Young,H Jerjen,B S Koribalski,Á R López-Sánchez

doi:10.1093/mnras/stu1646

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.

Highlights

In hierarchical structure formation scenarios (White & Rees 1978; Blumenthal et al 1984; Bullock, Kravtsov & Weinberg 2001), numerous low-mass dark matter haloes in the distant past were important building blocks for the high-mass galaxies observed today
We extend the procedures for performing photometry with a single Sersic function (KJRD08) by defining a double Sersic function: I = I0,i exp −(ri/αi)ni + I0,o exp −(ro/αo)no is the double surface brightness profiles (SBPs) in intensity units with i and o representing the inner and outer profile parameters as defined in equation (1)
We investigate the trends in optical–NIR colour for the entire KMK13 sample and the Local Volume (LV) dwarf irregular (dIrr) in this study and KJRD08 in Fig. 10 in order to determine whether colour–scaling relationships will allows us to compare our H-band parameters to those in the optical

Summary

Introduction

In hierarchical structure formation scenarios (White & Rees 1978; Blumenthal et al 1984; Bullock, Kravtsov & Weinberg 2001), numerous low-mass dark matter haloes in the distant past were important building blocks for the high-mass galaxies observed today. Dwarfs are the most common galaxy system (Ellis 1997; Marzke & da Costa 1997) and span a wide range of physical characteristics and environments (Karachentsev, Makarov & Kaisina 2013). As such dwarf galaxies through their physical. Alvensleben & Loose (1995) demonstrate that the NIR flux contribution of young massive stars is only significant in moderately strong star bursts where the gas continuum can contribute ∼20–40 per cent of the NIR flux for at least 100 Myr

Results

Discussion

Conclusion