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Morphological classification of local luminous infrared galaxies

Psychogyios, A. and Charmandaris, V. and Díaz-Santos, T. and Armus, L. and Haan, S. and Howell, J. and Le Floc'h, E. and Petty, S. M. and Evans, A. S. (2016) Morphological classification of local luminous infrared galaxies. Astronomy & Astrophysics, 591 (7). Art. No. A1. ISSN 0004-6361.

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We present analysis of the morphological classification of 89 luminous infrared galaxies (LIRGs) from the Great Observatories All-sky LIRG Survey (GOALS) sample, using non-parametric coefficients and compare their morphology as a function of wavelength. We rely on images that were obtained in the optical (B- and I-band) as well as in the infrared (H-band and 5.8 μm). Our classification is based on the calculation of Gini and the second order of light (M_(20)) non-parametric coefficients, which we explore as a function of stellar mass (M_⋆), infrared luminosity (L_(IR)), and star formation rate (SFR). We investigate the relation between M_(20), the specific SFR (sSFR) and the dust temperature (T_(dust)) in our galaxy sample. We find that M_(20) is a better morphological tracer than Gini, as it allows us to distinguish systems that were formed by double systems from isolated and post-merger LIRGs. The effectiveness of M_(20) as a morphological tracer increases with increasing wavelength, from the B to H band. In fact, the multi-wavelength analysis allows us to identify a region in the Gini-M_(20) parameter space where ongoing mergers reside, regardless of the band used to calculate the coefficients. In particular, when measured in the H band, a region that can be used to identify ongoing mergers, with minimal contamination from LIRGs in other stages. We also find that, while the sSFR is positively correlated with M_(20) when measured in the mid-infrared, i.e. star-bursting galaxies show more compact emission, it is anti-correlated with the B-band-based M_(20). We interpret this as the spatial decoupling between obscured and unobscured star formation, whereby the ultraviolet/optical size of an LIRG experience an intense dust-enshrouded central starburst that is larger that in the mid-infrared since the contrast between the nuclear to the extended disk emission is smaller in the mid-infrared. This has important implications for high redshift surveys of dusty sources, where sizes of galaxies are routinely measured in the rest-frame ultraviolet.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Charmandaris, V.0000-0002-2688-1956
Díaz-Santos, T.0000-0003-0699-6083
Armus, L.0000-0003-3498-2973
Evans, A. S.0000-0003-2638-1334
Additional Information:© 2016 ESO. Received 8 January 2016. Accepted 22 February 2016. We thank the referee for useful comments on the manuscript. We would also like to thank M. Vika (National Observatory of Athens), E. Vardoulaki (Argelander-Institut fur Astronomie) and K. Larson (Caltech) for many useful discussions and comments on this work. T.D-S. acknowledges support from ALMA-CONICYT project 31130005 and FONDECYT 1151239. A.P. and V.C. would like to acknowledge partial support from the EU FP7 Grant PIRSES-GA-2012-316788.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)31130005
Fondo Nacional de Desarrollo Científico y Tecnolόgico (FONDECYT)1151239
Marie Curie FellowshipPIRSES-GA-2012-316788
Subject Keywords:Galaxy: structure, infrared: galaxies, galaxies: evolution, galaxies: general, galaxies: starburst
Issue or Number:7
Record Number:CaltechAUTHORS:20160804-105757999
Persistent URL:
Official Citation:Morphological classification of local luminous infrared galaxies A. Psychogyios, V. Charmandaris, T. Diaz- Santos, L. Armus, S. Haan, J. Howell, E. Le Floc’h, S. M. Petty and A. S. Evans A&A, 591 (2016) A1 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:69442
Deposited By: Ruth Sustaita
Deposited On:04 Aug 2016 19:37
Last Modified:05 Nov 2019 05:46

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