| Description |
We propose to map a complete sample of 88 local star-formingmajor-merger pairs (median redshift 0.04), using PACS and SPIREphotometers in 6 bands at 70, 100, 160, 250, 350 and 500 micron. Thegoal is to set the local benchmarks for the cosmic evolution of theSFR-to-gas relation (the Kennicutt-Schmidt law) for major-mergerpairs, complementing a study on the K-S law for high-z mergers in theCOSMOS field using the PEP and HerMES data. The K-S law for majormergers may be significantly different from that for normal galaxies.The SPIRE imaging at 250, 350, and 500 micron, together with PACS mapsat shorter wavelengths, will probe the gas mass estimated from thedust mass. Dust is arguably the best proxy for total gas in galaxiesspanning a wide redshift range, given the fact that it is stillimpossible to observe the HI gas in high redshift galaxies through the21cm line emission. The PACS imaging at 70, 100, and 160 micron willmap the star formation in these systems, with good angular resolutions(6 -- 12 arcsec) and at the wavelengths near the peak of the infrareddust emission. The local sample closely matches the high-z COSMOSpairs sample (278 pairs) in the pair selection criteria, both beingstellar mass selected and including only spiral-spiral (S+S) andspiral-elliptical (S+E) major-merger pairs. This will facilitatestudies on stellar mass dependence of the K-S law for major mergerswith different redshifts. The large sample size enables goodstatistics even after separating the sample into subsamples of S+Spairs and of S+E pairs, and into several mass bins. |
