Year: 2019
Type: article
Abstract: Context . Galaxy mergers and interactions are an integral part of our basic understanding of how galaxies grow and evolve over time. However, the effect that galaxy mergers have on star-formation rates (SFRs) is contested, with observations of galaxy mergers showing reduced, enhanced, and highly enhanced star formation. Aims . We aim to determine the effect of galaxy mergers on the SFR of galaxies using statistically large samples of galaxies, totalling over 200 000, which is over a large redshift range from 0.0 to 4.0. Methods . We trained and used convolutional neural networks to create binary merger identifications (merger or non-merger) in the SDSS, KiDS, and CANDELS imaging surveys. We then compared the SFR, with the galaxy main sequence subtracted, of the merging and non-merging galaxies to determine what effect, if any, a galaxy merger has on SFR. Results . We find that the SFR of merging galaxies are not significantly different from the SFR of non-merging systems. The changes in the average SFR seen in the star-forming population when a galaxy is merging are small, of the order of a factor of 1.2. However, the higher the SFR is above the galaxy main sequence, the higher the fraction is for galaxy mergers. Conclusions . Galaxy mergers have little effect on the SFR of the majority of merging galaxies compared to the non-merging galaxies. The typical change in SFR is less than 0.1 dex in either direction. Larger changes in SFR can be seen but are less common. The increase in merger fraction as the distance above the galaxy main sequence increases demonstrates that galaxy mergers can induce starbursts.
Source: Astronomy and Astrophysics
Authors: W. J. Pearson, L. Wang, M. Alpaslan, I. Baldry, M. Bilicki, M. J. I. Brown, M. W. Grootes, B. W. Holwerda, T. D. Kitching, S. Kruk, F. F. S. van der Tak
Institutions: University of Groningen, Space Research Organisation Netherlands, New York University, Liverpool John Moores University, Center for Theoretical Physics, Polish Academy of Sciences, Monash University, Netherlands eScience Center, University of Louisville, European Space Agency, European Space Research and Technology Centre
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funders: National Science Foundation, U.S. Department of Energy, National Aeronautics and Space Administration, Alfred P. Sloan Foundation, Princeton University, Ohio State University, University of Washington, Johns Hopkins University, University of Pittsburgh, Case Western Reserve University, Drexel University, Universität Basel, University of Portsmouth, New Mexico State University, Deutsche Forschungsgemeinschaft, Rijksuniversiteit Groningen, Chinese Academy of Sciences, Nederlandse Organisatie voor Wetenschappelijk Onderzoek, Università degli Studi di Padova, Max-Planck-Gesellschaft, Max-Planck-Institut für Astronomie, Science and Technology Facilities Council, Center for Information Technology, U.S. Naval Observatory, Fermilab, Los Alamos National Laboratory
Awards: G2667869601, G4930006217, G58316358
OpenAlex ID: W2970953561