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Published December 2014 | Submitted + Published
Journal Article Open

The FUV to Near-IR Morphologies of Luminous Infrared Galaxies in the Goals Sample


We compare the morphologies of a sample of 20 luminous infrared galaxies (LIRGs) from the Great Observatories All-sky LIRG Survey (GOALS) in the FUV, B, I, and H bands, using the Gini (G) and M_(20) parameters to quantitatively estimate the distribution and concentration of flux as a function of wavelength. Hubble Space Telescope (HST) images provide an average spatial resolution of ~80pc. While our LIRGs can be reliably classified as mergers across the entire range of wavelengths studied here, there is a clear shift toward more negative M_(20) (more bulge-dominated) and a less significant decrease in G values at longer wavelengths. We find no correlation between the derived FUV G-M_(20) parameters and the global measures of the IR to FUV flux ratio (IRX). Given the fine resolution in our HST data, this suggests either that the UV morphology and IRX are correlated on very small scales, or that the regions emitting the bulk of the IR emission emit almost no FUV light. We use our multi-wavelength data to simulate how merging LIRGs would appear from z~0.5–3 in deep optical and near-infrared images such as the Hubble Ultra-Deep Field, and use these simulations to measure the G-M_(20) at these redshifts. Our simulations indicate a noticeable decrease in G, which flattens at z ≥ 2 by as much as 40%, resulting in mis-classifying our LIRGs as disk-like, even in the rest-frame FUV. The higher redshift values of M_(20) for the GOALS sources do not appear to change more than about 10% from the values at $z\sim 0$. The change in G-M_(20) is caused by the surface brightness dimming of extended tidal features and asymmetries, and also the decreased spatial resolution which reduced the number of individual clumps identified. This effect, seen as early as z~0.5, could easily lead to an underestimate of the number of merging galaxies at high-redshift in the rest-frame FUV.

Additional Information

© 2014 American Astronomical Society. Received 2014 March 31; accepted 2014 August 3; published 2014 October 30. Support for Program number HST-GO-11196 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. VC would like to acknowledge partial support from the EU FP7 Grant PIRSES-GA-2012-316788. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

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Published - 1538-3881_148_6_111.pdf

Submitted - 1408.2511v1.pdf


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August 22, 2023
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