Evidence for Impact of Galaxy Mergers on Stellar Kinematics of Early-type Galaxies

Journal Article · 03 February 2022 · The Astrophysical Journal

DOI: https://doi.org/10.3847/1538-4357/ac415d · OSTI ID:1983214

Yoon, Yongmin  ^[1]; Park, Changbom  ^[1]; Chung, Haeun  ^[2]; Lane, Richard R. ^[3]

---

1. Korea Institute for Advanced Study (KIAS), Seoul (Korea, Republic of)
2. Univ. of Arizona, Tucson, AZ (United States)
3. Universidad Bernardo O'Higgins, Santiago (Chile)

We provide observational evidence that galaxy mergers significantly affect stellar kinematics of early-type galaxies (ETGs) such as specific stellar angular momentum within the half-light radius ($${\lambda }_{{R}_{e}}$$) and kinematic misalignment (ψ_mis), using MaNGA integral field unit spectroscopic data that are in the Stripe 82 region of the Sloan Digital Sky Survey. In this study, tidal features around ETGs, which are detected in deep coadded images, are used as direct evidence for mergers that occurred recently. In the case of ETGs that do not have dust lanes, $${\lambda }_{{R}_{e}}$$ is lower in ETGs with tidal features than in those without tidal features (median $${\lambda }_{{R}_{e}}$$: 0.21 versus 0.39) in all stellar mass and Sérsic index ranges except the most massive bin, so that the fraction of ETGs with tidal features in slow rotators is more than twice as large as that in fast rotators (42% versus 18%). Moreover, ETGs with tidal features have larger ψ_mis than those without tidal features (mean ψ_mis: 28° versus 15°). By contrast, ETGs with dust lanes are fast rotators, and ETGs with both dust lanes and tidal features have the highest $${\lambda }_{{R}_{e}}$$ (median $${\lambda }_{{R}_{e}}$$: 0.59) among all ETG categories. In addition, ETGs with dust lanes have small ψ_mis regardless of the existence of tidal features (Ψ_mis<7$$^{°}_{.}$$5). Our results can be explained if mergers with different gas fractions generate merger remnants that have different kinematic properties.

• Research Organization: US Department of Energy (USDOE), Washington, DC (United States). Office of Science, Sloan Digital Sky Survey (SDSS)
• Sponsoring Organization: Korea Institute for Advanced Study (KIAS); USDOE Office of Science (SC)
• OSTI ID: 1983214
• Journal Information: The Astrophysical Journal, Journal Name: The Astrophysical Journal Journal Issue: 2 Vol. 925; ISSN 0004-637X
• Publisher: IOP PublishingCopyright Statement
• Country of Publication: United States
• Language: English