A1 Refereed original research article in a scientific journal

Galaxy and mass assembly (GAMA): comparing visually and spectroscopically identified galaxy merger samples




AuthorsDesmons Alice, Brough Sarah, Martínez-Lombilla Cristina, De Propris Roberto, Holwerda Benne, López-Sánchez Ángel R.

PublisherOxford University Press

Publication year2023

JournalMonthly Notices of the Royal Astronomical Society

Journal name in sourceMonthly Notices of the Royal Astronomical Society

Volume523

Issue3

First page 4381

Last page4393

eISSN1365-2966

DOIhttps://doi.org/10.1093/mnras/stad1639

Web address https://academic.oup.com/mnras/article/523/3/4381/7190650

Self-archived copy’s web addresshttps://research.utu.fi/converis/portal/detail/Publication/180600369


Abstract

We conduct a comparison of the merging galaxy populations detected by a sample of visual identification of tidal features around galaxies as well as spectroscopically detected close pairs of galaxies to determine whether our method of selecting merging galaxies biases our understanding of galaxy interactions. Our volume-limited parent sample consists of 852 galaxies from the Galaxy And Mass Assembly (GAMA) survey in the redshift range 0.04 ≤ z ≤ 0.20 and stellar mass range 9.50  ≤  log 10(M/M) ≤ 11.0⁠. We conduct our comparison using images from the Ultradeep layer of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) to visually classify galaxies with tidal features and compare these to the galaxies in the GAMA spectroscopic close-pair sample. We identify 198 galaxies possessing tidal features, resulting in a tidal feature fraction ftidal = 0.23 ± 0.02. We also identify 80 galaxies involved in close pairs, resulting in a close pair fraction fpair = 0.09 ± 0.01. Upon comparison of our tidal feature and close pair samples we identify 42 galaxies that are present in both samples, yielding a fraction fboth = 0.05 ± 0.01. We find evidence to suggest that the sample of close pairs of galaxies is more likely to detect early stage mergers, where two separate galaxies are still visible, and the tidal feature sample detects later-stage mergers, where only one galaxy nucleus remains visible. The overlap of the close pair and tidal feature samples likely detect intermediate-stage mergers. Our results are in good agreement with the predictions of cosmological hydrodynamical simulations regarding the populations of merging galaxies detected by close pair and tidal feature samples.


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