Local Benchmarks for the Evolution of Major-Merger Galaxies - Spitzer Observations of a K-Band Selected Sample - Astrophysics > Cosmology and Nongalactic AstrophysicsReportar como inadecuado




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Abstract: We present Spitzer observations for a sample of close major-merger galaxypairs KPAIR sample selected from 2MASS-SDSS-DR3 cross-matches. The goals areto study the star formation activity in these galaxies and to set a local benchmark for the cosmic evolution of close major mergers. The Spitzer KPAIR sample27 pairs, 54 galaxies includes all spectroscopically confirmed S+S and S+Epairs in a parent sample that is complete for primaries brighter than K=12.5mag, projected separations of 5< s < 20 kpc-h, and mass ratios<2.5. The Spitzerdata consist of images in 7 bands 3.6, 4.5, 5.8, 8, 24, 70, 160 um. Comparedto single spiral galaxies in a control sample, only spiral galaxies in S+Spairs show significantly enhanced specific star formation rate sSFR=SFR-M,whereas spiral galaxies in S+E pairs do not. Furthermore, the SFR enhancementof spiral galaxies in S+S pairs is highly mass-dependent. Only those with $ mM \gsim 10^{10.5} M \sun$ show significant enhancement. Relatively low mass$ m M \sim 10^{10} M \sun$ spirals in S+S pairs have about the same SFR-Mcompared to their counterparts in the control sample. There is evidence for acorrelation between the global star formation activities but not the nuclearactivities of the component galaxies in massive S+S major-merger pairs the-Holmberg effect-. There is no significant difference in the SFR-M between theprimaries and the secondaries, nor between spirals of SEP<1 and those of SEP.1.The contribution of KPAIR galaxies to the cosmic SFR density in the localuniverse is only 1.7%.



Autor: C. Kevin Xu, Donovan Domingue, Yi-Wen Cheng, Nanyao Lu, Jiasheng Huang, Yu Gao, Joseph M. Mazzarella, Roc Cutri, Wei-Hsin Sun, Ja

Fuente: https://arxiv.org/







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