Star formation concentration as a tracer of environmental quenching in action: a study of the eagle and c-eagle simulations

Wang, Di; Lagos, Claudia D P; Croom, Scott M; Wright, Ruby J; Bahé, Yannick M; Bryant, Julia J; van de Sande, Jesse; Vaughan, Sam P

Abstract

We study environmental quenching in the EAGLE/C-EAGLE cosmological hydrodynamic simulations over the last 11 Gyr (i.e. z = 0–2). The simulations are compared with observations from the SAMI Galaxy Survey at z = 0. We focus on satellite galaxies in galaxy groups and clusters (1012 M< M200 < 3 × 1015 M We study environmental quenching in the EAGLE/C-EAGLE cosmological hydrodynamic simulations over the last 11 Gyr (i.e. z = 0–2). The simulations are compared with observations from the SAMI Galaxy Survey at z = 0. We focus on satellite galaxies in galaxy groups and clusters (⁠ ≲ M200 < ⁠). A star-formation concentration index [C-index = log10(r50, SFR/r50, rband)] is defined, which measures how concentrated star formation is relative to the stellar distribution. Both EAGLE/c-EAGLE and SAMI show a higher fraction of galaxies with low C-index in denser environments at z = 0–0.5. Low C-index galaxies are found below the SFR–M⋆ main sequence (MS), and display a declining specific star formation rate (sSFR) with increasing radii, consistent with ‘outside-in’ environmental quenching. Additionally, we show that C-index can be used as a proxy for how long galaxies have been satellites. These trends become weaker at increasing redshift and are absent by z = 1–2. We define a quenching time-scale tquench as how long it takes satellites to transition from the MS to the quenched population. We find that simulated galaxies experiencing ‘outside-in’ environmental quenching at low redshift (z = 0 ∼ 0.5) have a long quenching time-scale (median tquench > 2 Gyr). The simulated galaxies at higher redshift (z = 0.7 ∼ 2) experience faster quenching (median tquench < 2 Gyr). At z ≳ 1–2 galaxies undergoing environmental quenching have decreased sSFR across the entire galaxy with no ‘outside-in’ quenching signatures and a narrow range of C-index, showing that on average environmental quenching acts differently than at z ≲ 1.

Citation

Wang, D., Lagos, C. D. P., Croom, S. M., Wright, R. J., Bahé, Y. M., Bryant, J. J., …Vaughan, S. P. (2023). Star formation concentration as a tracer of environmental quenching in action: a study of the eagle and c-eagle simulations. Monthly Notices of the Royal Astronomical Society, 523(4), 6020-6040. https://doi.org/10.1093/mnras/stad1864

• Journal Article Type: Article
• Acceptance Date: Jun 13, 2023
• Online Publication Date: Jun 22, 2023
• Publication Date: 2023-08
• Deposit Date: Dec 19, 2023
• Publicly Available Date: Dec 20, 2023
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 523
• Issue: 4
• Pages: 6020-6040
• DOI: https://doi.org/10.1093/mnras/stad1864
• Public URL: https://durham-repository.worktribe.com/output/2048178