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arXiv · 1807.02952

Shocked POststarburst Galaxy Survey. III. The Ultraviolet Properties of SPOGs

Felipe Ardila·Katherine Alatalo·Lauranne Lanz·Philip N. Appleton·Rachael L. Beaton·Theodoros Bitsakis·Sabrina L. Cales·Jesús Falcón-Barroso·Lisa J. Kewley·Anne M. Medling·John S. Mulchaey·Kristina Nyland·Jeffrey A. Rich·C. Meg Urry
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Abstract

The Shocked POststarburst Galaxy Survey (SPOGS) aims to identify galaxies in the transitional phase between actively star-forming and quiescence with nebular lines that are excited from shocks rather than star formation processes. We explored the ultraviolet (UV) properties of objects with near-ultraviolet (NUV) and far-ultraviolet (FUV) photometry from archival GALEX data; 444 objects were detected in both bands, 365 in only NUV, and 24 in only FUV, for a total of 833 observed objects. We compared SPOGs to samples of Star-forming galaxies (SFs), Quiescent galaxies (Qs), classical E+A post-starburst galaxies, active galactic nuclei (AGN) host galaxies, and interacting galaxies. We found that SPOGs have a larger range in their FUV-NUV and NUV-r colors compared to most of the other samples, although all of our comparison samples occupied color space inside of the SPOGs region. Based on their UV colors, SPOGs are a heterogeneous group, possibly made up of a mixture of SFs, Qs, and/or AGN. Using Gaussian mixture models, we are able to recreate the distribution of FUV-NUV colors of SPOGs and E+A galaxies with different combinations of SFs, Qs, and AGN. We find that the UV colors of SPOGs require a >60% contribution from SFs, with either Qs or AGN representing the remaining contribution, while UV colors of E+A galaxies required a significantly lower fraction of SFs, supporting the idea that SPOGs are at an earlier point in their transition from quiescent to star-forming than E+A galaxies.

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Felipe Ardila, Katherine Alatalo, Lauranne Lanz, Philip N. Appleton, Rachael L. Beaton, Theodoros Bitsakis, Sabrina L. Cales, Jesús Falcón-Barroso, Lisa J. Kewley, Anne M. Medling, John S. Mulchaey, Kristina Nyland, Jeffrey A. Rich, C. Meg Urry. 2018-07-09. Shocked POststarburst Galaxy Survey. III. The Ultraviolet Properties of SPOGs. https://doi.org/10.3847/1538-4357%2Faad0a3

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