Disparate effects of circumgalactic medium angular momentum in IllustrisTNG and SIMBA

¹ Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China
² University of Chinese Academy of Sciences, Beijing 100049, China
³ Department of Astronomy, Tsinghua University, Beijing 100084, China
⁴ Institute for Computational Cosmology, Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK
⁵ Departamento de Física Teórica, M-8, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain
⁶ Centro de Investigación Avanzada en Física Fundamental (CIAFF), Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain
⁷ Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ, UK
⁸ University of the Western Cape, Bellville, Cape Town 7535, South Africa
⁹ South African Astronomical Observatories, Observatory, Cape Town 7925, South Africa

^⋆ Corresponding authors; liukexin@shao.ac.cn, guohong@shao.ac.cn

Received: 14 September 2024
Accepted: 20 November 2024

Abstract

In this study, we examine the role of the circumgalactic medium (CGM) angular momentum (j_CGM) on star formation in galaxies, whose influence is currently not well understood. The analysis utilises central galaxies from two hydrodynamical simulations, SIMBA and IllustrisTNG. We observe a substantial divergence in how star formation rates correlate with CGM angular momentum between the two simulations. Specifically, quenched galaxies in IllustrisTNG show higher j_CGM than their star-forming counterparts with similar stellar masses, while the reverse is true in SIMBA. This difference is attributed to the distinct active galactic nucleus (AGN) feedback mechanisms active in each simulation. Moreover, both simulations demonstrate similar correlations between j_CGM and environmental angular momentum (j_Env) in star-forming galaxies, but these correlations change notably when kinetic AGN feedback is present. In IllustrisTNG, quenched galaxies consistently show higher j_CGM compared to their star-forming counterparts with the same j_Env, a trend not seen in SIMBA. Examining different AGN feedback models in SIMBA, we further confirm that AGN feedback significantly influences the CGM gas distribution, although the relationship between the cold gas fraction and the star formation rate (SFR) remains largely stable across different feedback scenarios.