GOODS-Herschel: the impact of galaxy-galaxy interactions on the far-infrared properties of galaxies

¹ Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu, CNRS, Université Paris Diderot, CE-Saclay, 91191 Gif-sur-Yvette, France
e-mail: hwang.ho.seong@gmail.com
² National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719, USA
³ Department of Physics and Institute of Theoretical & Computational Physics, University of Crete, 71003 Heraklion, Greece
⁴ IESL/Foundation for Research and Technology - Hellas, 71110 Heraklion, Greece
⁵ Laboratoire d’Astrophysique de Marseille, OAMP, Université Aix-Marseille, CNRS, 38 rue Frédéric Joliot-Curie, 13388 Marseille Cedex 13, France
⁶ Institut d’Astrophysique de Paris, UMR 7095, CNRS, UPMC Univ. Paris 06, 98bis boulevard Arago, 75014 Paris, France
⁷ Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH, UK
⁸ Herschel Science Centre, European Space Astronomy Centre, Villanueva de la Cañada, 28691 Madrid, Spain
⁹ Max-Planck-Institut für Extraterrestrische Physik (MPE), Postfach 1312, 85741, Garching, Germany

Received: 14 June 2011
Accepted: 8 September 2011

Abstract

Aims. We study the impact of galaxy-galaxy interactions on the far-infrared properties of galaxies and its evolution at 0 < z < 1.2.

Methods. Using the high-z galaxies in the fields of Great Observatories Origins Deep Survey (GOODS) observed by the Herschel Space Observatory in the framework of the GOODS-Herschel key program and the local IRAS or AKARI-selected galaxies in the field of Sloan Digital Sky Survey Data Release 7, we investigate the dependence of galaxy properties on the morphology of and the distance to the nearest neighbor galaxy.

Results. We find that the star-formation rates (SFRs) and the specific SFRs (SSFRs) of galaxies on average depend on the morphology of and the distance to the nearest neighbor galaxy in this redshift range. When a late-type galaxy has a close neighbor galaxy, the SFR and the SSFR increase as it approaches a late-type neighbor, which is supported by Kolmogorov-Smirnov (K-S) and Monte Carlo (MC) tests with a significance level of  >99%. However, the SFR and the SSFR decrease or do not change much as the galaxy approaches an early-type neighbor. The bifurcations of SFRs and SSFRs depending on the neighbor’s morphology seem to occur at R_n ≈ 0.5r_vir,nei (virial radius of the neighbor), which is supported by K-S and MC tests with a significance level of  >98%. For all redshift bins, the SSFRs of late-type galaxies interacting with late-type neighbors are increased by factors of about 1.8  ±  0.7 and 4.0  ±  1.2 compared to those of non-interacting galaxies when the pair separation is smaller than 0.5r_vir,nei and 0.1r_vir,nei, respectively. The dust temperature of both local and high-z late-type galaxies that strongly interact with late-type neighbors (i.e. R_n ≤ 0.1r_vir,nei) appears to be higher than that of non-interacting galaxies with a significance level of 96−99%. However, the dust temperature of local late-type galaxies that strongly interact with early-type neighbors seems to be lower than or similar to that of non-interacting galaxies.

Conclusions. Our results suggest that galaxy-galaxy interactions and mergers have been strongly affecting the SFR and the dust properties of star-forming galaxies over at least 8 billion years.