Morphological Classification of local Luminous Infrared Galaxies
Galaxy structure in the low-redshift universe
Alexandros Psychogyios
Department of Physics, University of Crete
V. Charmandaris (IAASARS,National Observatory of Athens,Greece, University of Crete, Greece), L.Armus(SSC/Caltech,USA), T.Diaz-Santos(Diego Portales University, Santiago, Chile),J.Howell(IPAC/Caltech,USA),E.Le Floc'h(CEA Saclay,France)
Luminous infrared galaxies (LIRGs) dominate the infrared background and the star formation rate density at z close to 1. Despite the rarity of their local counterparts, their study is of paramount importance as they allow exploration of their detailed morphologies that cannot be done (owing to resolution limitations) at higher redshifts. Quantifying the morphology of local LIRGs as a function of wavelength using non-parametric coefficients gives the ability to search for clues of merging signatures in an automated way.
I will present an analysis of the morphological classification of 89 LIRGs from the Great Observatories All-sky LIRG Survey (GOALS) sample, using high-resolution HST imagery at B, I, and H band as well as 5.8μm imaging by Spitzer. This classification is based on the calculation of Gini and M20 non-parametric coefficients. We explore how these coefficients vary as a function of stellar mass and infrared luminosity. In addition, we investigate the relation between M20, the specific star formation rate (sSFR) and the dust temperature in this galaxy sample and find that the effectiveness of M20 as a morphological tracer increases with increasing wavelength, from the B to H band and identify a region in the Gini-M20 parameter space where ongoing mergers reside, regardless of the band. We also find that, while the sSFR is positively correlated with M20 when measured in the mid-infrared, i.e. star-bursting galaxies show more compact emission, it is anti-correlated with the B-band-based M20. We interpret this as the spatial decoupling between obscured and un-obscured star formation.


09:00 - 10:30
BS - Lecture Theatre A25 (121)