Time-scales for the effects of interactions on galaxy properties and SMBH growth

ABSTRACT Galaxy interaction and merging have clear effects on the systems involved. We find an increase in the star formation rate (SFR), potential ignition of active galactic nuclei (AGNs), and significant morphology changes. However, at what stage during interactions or mergers these changes begin to occur remains an open question. With a combination of machine learning and visual classification, we select a sample of 3162 interacting and merging galaxies in the Cosmic Evolutionary Survey (COSMOS) field across a redshift range of 0.0–1.2. We divide this sample into four distinct stages of interaction based on their morphology, each stage representing a different phase of the dynamical time-scale. We use the rich ancillary data available in COSMOS to probe the relation between interaction stage, stellar mass, SFR, and AGN fraction. We find that the distribution of SFRs rapidly changes with stage for mass distributions consistent with being drawn from the same parent sample. This is driven by a decrease in the fraction of red sequence galaxies (from 17 per cent as close pairs to 1.4 per cent during merging) and an increase in the fraction of starburst galaxies (from 7 per cent to 32 per cent). We find that the AGN fraction increases by a factor of 1.2 only at coalescence. We find that the effects of interaction peak at the point of closest approach and coalescence of the two systems. We show that the point in time of the underlying dynamical time-scale – and its related morphology – is as important to consider as its projected separation.

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Publication Details

Journal
Monthly Notices of the Royal Astronomical Society
Published
2025-04-03
DOI
https://doi.org/10.1093/mnras/staf541
Citations
1
Primary Topic
Engineering Applied Research
Type
article
Field-Weighted Citation Impact
0.95

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Time-scales for the effects of interactions on galaxy properties and SMBH growth

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Monthly Notices of the Royal Astronomical Society
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article

Time-scales for the effects of interactions on galaxy properties and SMBH growth

David O’Ryan, Tobias Géron, Matthew R Thorne, G. Gozaliasl, Anton M. Koekemoer, John R. Weaver, Sandor Kruk, Brooke Simmons, Izzy L. Garland, Karen L. Masters, William C. Keel, Steven Gillman, Andreas L. Faisst, Sofia Guedes Vaz Pinto, Montoya C Oscar, Mason Redden, Emily R Walls, Deneth Weerasinghe
article en
1 citations

Abstract

ABSTRACT Galaxy interaction and merging have clear effects on the systems involved. We find an increase in the star formation rate (SFR), potential ignition of active galactic nuclei (AGNs), and significant morphology changes. However, at what stage during interactions or mergers these changes begin to occur remains an open question. With a combination of machine learning and visual classification, we select a sample of 3162 interacting and merging galaxies in the Cosmic Evolutionary Survey (COSMOS) field across a redshift range of 0.0–1.2. We divide this sample into four distinct stages of interaction based on their morphology, each stage representing a different phase of the dynamical time-scale. We use the rich ancillary data available in COSMOS to probe the relation between interaction stage, stellar mass, SFR, and AGN fraction. We find that the distribution of SFRs rapidly changes with stage for mass distributions consistent with being drawn from the same parent sample. This is driven by a decrease in the fraction of red sequence galaxies (from 17 per cent as close pairs to 1.4 per cent during merging) and an increase in the fraction of starburst galaxies (from 7 per cent to 32 per cent). We find that the AGN fraction increases by a factor of 1.2 only at coalescence. We find that the effects of interaction peak at the point of closest approach and coalescence of the two systems. We show that the point in time of the underlying dynamical time-scale – and its related morphology – is as important to consider as its projected separation.

Monthly Notices of the Royal Astronomical SocietyVol. 539(4)
California Institute of Technology (US), Space Telescope Science Institute (US), Haverford College (US), University of Alabama (US), University of Toronto (CA), Masaryk University (CZ), University of Massachusetts Amherst (US), European Space Agency (FR), Dawn Research (United States) (US), European Space Astronomy Centre (ES), DAWN Center for Independent Living (US), Université Bourgogne Franche-Comté (FR), Centro de Astrobiología (ES), Infrared Processing and Analysis Center (US), Lancaster University (GB), Technical University of Denmark (DK), Aalto University (FI)
National Research Foundation, Danmarks Grundforskningsfond, Grantová Agentura České Republiky, European Southern Observatory, Science and Technology Facilities Council
Openalex Percentile: Top 27%
Engineering Applied Research
0.95
DOIOpen Access PDFOpenAlex
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