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Interactions and star formation

Published online by Cambridge University Press:  12 September 2016

Johan H. Knapen
Affiliation:
Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife, Spain Departamento de Astrofísica, Universidad de La Laguna, E-38205 La Laguna, Tenerife, Spain
Mauricio Cisternas
Affiliation:
Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife, Spain Departamento de Astrofísica, Universidad de La Laguna, E-38205 La Laguna, Tenerife, Spain
Miguel Querejeta
Affiliation:
Max Planck Institute for Astronomy, Königstuhl 17, 69117, Heidelberg, Germany
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Abstract

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We investigate the influence of interactions on the star formation by studying a sample of almost 1500 of the nearest galaxies, all within a distance of ~45 Mpc. We define the massive star formation rate (SFR), as measured from far-IR emission, and the specific star formation rate (SSFR), which is the former quantity normalized by the stellar mass of the galaxy, and explore their distribution with morphological type and with stellar mass. We then calculate the relative enhancement of these quantities for each galaxy by normalizing them by the median SFR and SSFR values of individual control populations of similar non-interacting galaxies. We find that both SFR and SSFR are enhanced in interacting galaxies, and more so as the degree of interaction is higher. The increase is, however, moderate, reaching a maximum of a factor of 1.9 for the highest degree of interaction (mergers). The SFR and SSFR are enhanced statistically in the population, but in most individual interacting galaxies they are not enhanced at all. We discuss how those galaxies with the largest SFR and/or SSFR enhancement can be defined as starbursts. We argue that this study, based on a representative sample of nearby galaxies, should be used to place constraints on studies based on samples of galaxies at larger distances.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2016 

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