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Minor mergers: fundamental but unexplored drivers of galaxy evolution

Published online by Cambridge University Press:  17 August 2016

Sugata Kaviraj
Sugata Kaviraj*
Affiliation:
Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
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Abstract

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We use the SDSS Stripe 82 to study the stellar-mass growth that is triggered by minor mergers in local disk galaxies. Since major mergers destroy disks and create spheroids, morphologically disturbed spirals are likely remnants of minor mergers (since the disk remains intact). Disturbed spirals exhibit enhanced specific star formation rates (SSFRs), with the enhancement increasing in galaxies with ‘later’ morphological type (that have larger gas reservoirs and smaller bulges). By combining the SSFR enhancements with the fraction of time spirals in various morphological classes spend in this ‘enhanced’ mode, we estimate that ~40% of the star formation activity in local spirals is directly triggered by minor mergers. Combining our results with the star formation in local early-type galaxies – which is almost completely driven by minor mergers – suggests that around half the star formation activity at the present day is likely to be triggered by the minor-merger process.

Keywords

galaxies: formation – galaxies: evolution – galaxies: interactions – galaxies: spirals
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 11 , Symposium S319: Galaxies at High Redshift and Their Evolution Over Cosmic Time , August 2015 , pp. 130 - 136
Copyright
Copyright © International Astronomical Union 2016 

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