The importance of minor-merger-driven star formation and black hole growth in disc galaxies

摘要: We use the SDSS Stripe 82 to empirically quantify stellar-mass and black-hole growth triggered by minor mergers in local spiral (disk) galaxies. Since major destroy disks create spheroids, morphologically disturbed spirals are likely remnants of mergers. Disturbed exhibit enhanced specific star formation rates (SSFRs), enhancement increasing galaxies 'later' morphological type (which have more gas smaller bulges). By combining SSFR enhancements with fraction time spend this 'enhanced' mode, we estimate that ~40% is directly The also higher nuclear-accretion rates, implying enhance rate central black hole. However, accretion shows a lower than SSFR, suggesting coupling between weak minor-merger-driven episodes. Given significant mergers, weaker may contribute large intrinsic scatter observed stellar vs. mass relation spirals. Combining our results early-type -- which accounts for ~14% budget suggests around half activity Universe minor-merger process.