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Published November 20, 2012 | Published
Journal Article Open

Cosmic Evolution of Star Formation Enhancement in Close Major-merger Galaxy Pairs Since z = 1


The infrared (IR) emission of "M_* galaxies" (10^(10.4) ≤ M_(star) ≤ 10^(11.0) M_☉) in galaxy pairs, derived using data obtained in Herschel (PEP/HerMES) and Spitzer (S-COSMOS) surveys, is compared to that of single-disk galaxies in well-matched control samples to study the cosmic evolution of the star formation enhancement induced by galaxy-galaxy interaction. Both the mean IR spectral energy distribution and mean IR luminosity of star-forming galaxies (SFGs) in SFG+SFG (S+S) pairs in the redshift bin of 0.6 < z < 1 are consistent with no star formation enhancement. SFGs in S+S pairs in a lower redshift bin of 0.2 < z < 0.6 show marginal evidence for a weak star formation enhancement. Together with the significant and strong sSFR enhancement shown by SFGs in a local sample of S+S pairs (obtained using previously published Spitzer observations), our results reveal a trend for the star formation enhancement in S+S pairs to decrease with increasing redshift. Between z = 0 and z = 1, this decline of interaction-induced star formation enhancement occurs in parallel with the dramatic increase (by a factor of ~10) of the sSFR of single SFGs, both of which can be explained by the higher gas fraction in higher-z disks. SFGs in mixed pairs (S+E pairs) do not show any significant star formation enhancement at any redshift. The difference between SFGs in S+S pairs and in S+E pairs suggests a modulation of the sSFR by the intergalactic medium (IGM) in the dark matter halos hosting these pairs.

Additional Information

© 2012 American Astronomical Society. Received 2012 June 15; accepted 2012 October 3; published 2012 November 6. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. Dr. Xianzhong Zheng is thanked for kindly providing the software and instructions for the "clean stacking."We acknowledge support from the Science and Technology Facilities Council (grant No. ST/I000976/1). PACS has been developed by a consortium of institutes led by MPE (Germany) and including UVIE (Austria); KU Leuven, CSL, IMEC (Belgium); CEA, LAM (France); MPIA (Germany); INAF-IFSI/OAA/OAP/OAT, LENS, SISSA (Italy); IAC (Spain). This development has been supported by the funding agencies BMVIT (Austria), ESA-PRODEX (Belgium), CEA/CNES (France), DLR (Germany), ASI/INAF (Italy), and CICYT/MCYT (Spain). SPIRE has been developed by a consortium of institutes led by Cardiff University (UK) and including: the University of Lethbridge (Canada); NAOC (China); CEA, LAM (France); IFSI, the University of Padua (Italy); IAC (Spain); Stockholm Observatory (Sweden); Imperial College London, RAL, UCLMSSL, UKATC, the University of Sussex (UK); and Caltech, JPL, NHSC, the University of Colorado (USA). This development has been supported by national funding agencies: CSA (Canada); NAOC (China); CEA, CNES, CNRS (France); ASI (Italy);MCINN (Spain); SNSB (Sweden); STFC, UKSA (UK); and NASA (USA). The data presented in this paper will be released through the Herschel Database in Marseille (HeDaM, http://hedam.oamp.fr/HerMES).

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