SCYON Abstract

Received on December 12 2011

The merger history, AGN and dwarf galaxies of HicksonCompactGroup59

Authors	I.S. Konstantopoulos ((¹), S.C. Gallagher (²), K. Fedotov (^2,3), P.R. Durrell (⁴), P. Tzanavaris (^5,6,7), A.R. Hill (²), A.I. Zabludoff (⁸), M.L. Maier (⁹), D.M. Elmegreen (¹⁰), J.C. Charlton (¹), K.E. Johnson (^11,12), W.N. Brandt (¹), L.M. Walker (¹¹), M. Eracleous (¹), A. Maybhate (¹³), C. Gronwall (¹), J. English (¹⁴), A.E. Hornschemeier (⁵), J.S. Mulchaey (¹⁵)
Affiliation	(¹) Department of Astronomy; Astrophysics, The Pennsylvania State University, University Park, PA 16802 (²) Department of Physics & Astronomy, The University of Western Ontario, London, ON, N6A 3K7, Canada (³) Herzberg Institute of Astrophysics, Victoria, BC V9E 2E7, Canada (⁴) Department of Physics & Astronomy, Youngstown State University, Youngstown, OH 44555 (⁵) Laboratory for X-ray Astrophysics, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (⁶) Department of Physics; Astronomy, The Johns Hopkins University, Baltimore, MD 21218 (⁷) NASA Post-doctoral Program Fellow (⁸) Steward Observatory, University of Arizona, Tucson, AZ 85721 (⁹) Gemini Observatory, Casilla 603, Colina el Pino S/N, La Serena, Chile (¹⁰) Department of Physics & Astronomy, Vassar College, Poughkeepsie, NY 12604 (¹¹) University of Virginia, Charlottesville, VA (¹²) National Radio Astronomy Observatory, Charlottesville, VA (¹³) Space Telescope Science Institute, Baltimore, MD (¹⁴) University of Manitoba, Winnipeg, MN, Canada (¹⁵) Carnegie Observatories, Pasadena, CA 91101
Accepted by	Astrophysical Journal
Contact	iraklis@astro.psu.edu
URL	https://files.me.com/iraklisk/ysogey
Links

Abstract

Compact group galaxies often appear unaffected by their unusually dense environment. Closer examination can, however, reveal the subtle, cumulative effects of multiple galaxy interactions. Hickson Compact Group(HCG)59 is an excellent example of this situation. We present a photometric study of this group in the optical (HST), infrared (Spitzer) and X-ray (Chandra) regimes aimed at characterizing the star formation and nuclear activity in its constituent galaxies and intra-group medium. We associate five dwarf galaxies with the group and update the velocity dispersion, leading to an increase in the dynamical mass of the group of up to a factor of 10 (to 2.8x10¹³M(sun)), and a subsequent revision of its evolutionary stage. Star formation is proceeding at a level consistent with the morphological types of the four main galaxies, of which two are star-forming and the other two quiescent. Unlike in some other compact groups, star-forming complexes across HCG59 closely follow mass-radius scaling relations typical of nearby galaxies. In contrast, the ancient globular cluster populations in galaxies HCG59A and B show intriguing irregularities, and two extragalactic HII regions are found just west of B. We age-date a faint stellar stream in the intra-group medium at ~1 Gyr to examine recent interactions. We detect a likely low-luminosity AGN in HCG59A by its ~10⁴⁰Lumin X-ray emission; the active nucleus rather than star formation can account for the UV+IR SED. We discuss the implications of our findings in the context of galaxy evolution in dense environments.