A Signature of Merger Driven Star Formation in Spiral Galaxies
Tim Dolley (Monash University)
Local galaxy star formation is thought to be dominated by secular evolution, but star formation triggered by mergers must also contribute. We have measured the clustering of spiral galaxies as a function of specific star formation rate (SSFR), for a morphology selected sample. We find that large scale clustering of spiral galaxies is independent of SSFR, indicating spiral galaxies with high and low SSFRs typically reside within the same mass dark matter halos. On intermediate scales (~500kpc), spiral galaxies with high SSFRs have a deficiency in satellite companions, but an excess of satellite companions at smaller scales (~50kpc). This appears to be the signature of recent or ongoing mergers, where the suppressed correlation function at ~500kpc scales is due to the infall of a satellite companion.