Morphological classification of local luminous infrared galaxies
Abstract
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.
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.Attached Files
Published - aa28093-16.pdf
Submitted - 1602.08500v1.pdf
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Additional details
- Eprint ID
- 69442
- Resolver ID
- CaltechAUTHORS:20160804-105757999
- 31130005
- Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)
- 1151239
- Fondo Nacional de Desarrollo Científico y Tecnolόgico (FONDECYT)
- PIRSES-GA-2012-316788
- Marie Curie Fellowship
- Created
-
2016-08-04Created from EPrint's datestamp field
- Updated
-
2021-11-11Created from EPrint's last_modified field
- Caltech groups
- Infrared Processing and Analysis Center (IPAC)