Herschel Observations of Major Merger Pairs at z=0: Dust Mass and Star Formation

Creators: Cao, Chen; Xu, Cong Kevin; Domingue, Donovan; Buat, Veronique; Cheng, Yi-Wen; Gao, Yu; Huang, Jiasheng; Jarrett, Thomas H.; Lisenfeld, Ute; Lu, Nanyao; Mazzarella, Joe; Sun, Wei-Hsin; Wu, Hong; Yun, Min S.; Ronca, Joseph; Jacques, Allison

Abstract

We present Herschel PACS and SPIRE far-infrared (FIR) and submillimeter imaging observations for a large K-band selected sample of 88 close major-merger pairs of galaxies (H-KPAIRs) in 6 photometric bands (70, 100, 160, 250, 350, and 500 μm). Among 132 spiral galaxies in the 44 spiral–spiral (S+S) pairs and 44 spiral–elliptical (S+E) pairs, 113 are detected in at least 1 Herschel band. The star formation rate (SFR) and dust mass (M_(dust)) are derived from the IR SED fitting. The mass of total gas (M_(gas)) is estimated by assuming a constant dust-to-gas mass ratio of 0.01. Star-forming spiral galaxies (SFGs) in S+S pairs show significant enhancements in both specific star formation rate (sSFR) and star formation efficiency (SFE), while having nearly the same gas mass compared to control galaxies. On the other hand, for SFGs in S+E pairs, there is no significant sSFR enhancement and the mean SFE enhancement is significantly lower than that of SFGs in S+S pairs. This suggests an important role for the disk–disk collision in the interaction-induced star formation. The M_(gas) of SFGs in S+E pairs is marginally lower than that of their counterparts in both S+S pairs and the control sample. Paired galaxies with and without interaction signs do not differ significantly in their mean sSFR and SFE. As found in previous works, this much larger sample confirms that the primary and secondary spirals in S+S pairs follow a Holmberg effect correlation on sSFR.

Additional Information

© 2016 The American Astronomical Society. Received 2015 September 7; accepted 2015 December 10; published 2016 February 10. We thank the anonymous referee for helpful comments and suggestions. We acknowledge useful discussions with Dr. Yinghe Zhao, and thank Dr. Yuyen Chang for the help with data tables of 1M galaxies from SDSS+WISE. C.C. and Y.G. are supported by NSFC-11503013, NSFC-11420101002, NSFC-10978014, NSFC-11173059, NSFC-11390373, and CAS-XDB09000000. U.L. acknowledges support by the research projects AYA2011-24728 and AYA2014-53506-P from the Spanish Ministerio de Economía y Competividad and the Junta de Andalucía (Spain). The Herschel spacecraft was designed, built, tested, and launched under a contract with ESA, managed by the Herschel/Planck Project team through an industrial consortium under the overall responsibility of the prime contractor Thales Alenia Space (Cannes), and including Astrium (Friedrichshafen), responsible for the payload module and for system testing at the spacecraft level, Thales Alenia Space (Turin), responsible for the service module, and Astrium (Toulouse) responsible for the telescope, with an excess of a hundred subcontractors. HCSS/HSpot/HIPE are joint developments by the Herschel Science Ground Segment Consortium, consisting of ESA, the NASA Herschel Science Center, and the HIFI, PACS and SPIRE consortia. 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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