From large-scale environment to CGM angular momentum to star forming activities -- I: star-forming galaxies

Abstract

The connection between halo gas acquisition through the circumgalactic medium (CGM) and galaxy star formation has long been studied. In this series of two papers, we put this interplay within the context of the galaxy environment on large scales (several hundreds of kpc), which, to a certain degree, maps out various paths for galaxy interactions. We use the IllustrisTNG-100 simulation to demonstrate that the large-scale environment modulates the circumgalactic gas angular momentum, resulting in either enhanced (Paper I) or suppressed (Paper II) star formation inside a galaxy. In this paper (Paper I), we show that the large-scale environment around a star-forming galaxy is often responsible for triggering new episodes of star formation. Such an episodic star formation pattern is well synced with a pulsating motion of the circumgalactic gas, which, on the one hand receives angular momentum modulations from the large-scale environment, yielding in-spiralling gas to fuel the star-forming reservoir, while, on the other hand, is affected by the feedback activities from the galaxy centre. As a result, a present-day star-forming galaxy may have gone through several cycles of star-forming and quiescent phases during its evolutionary history, with the circumgalactic gas carrying out a synchronized cadence of "breathing in and out" motions out to ∼ 100 kpc.

Quenched, bulge-dominated, but dynamically cold galaxies in IllustrisTNG and their real-world counterparts

“…And further, what causes the high CGM angular momentum in these galaxies? We address these interesting questions in our another series of studies (Wang et al 2021;Lu et al 2021a), in which the connections between the environment torque field, the CGM gas, and the inner star-formation activities in galaxies are studied.…”

From large-scale environment to CGM angular momentum to star forming activities -- II: quenched galaxies

“…Specifically we use the IllustrisTNG-100 simulation (Marinacci et al 2018;Naiman et al 2018;Nelson et al 2018;Pillepich et al 2018b;Springel et al 2018) to investigate modulations of star formation induced by the circumgalactic medium (CGM), which inherits angular momentum from the galaxy's largescale environment. In Paper I of this series (Wang et al 2021), we focus on present-day star-forming disk galaxies and investigate their typically episodic star-formation activities, intermittent with quenched phases. In this paper, we study these effects for present-day quenched galaxies.…”

Submillimetre galaxies in two massive protoclusters at z = 2.24: witnessing the enrichment of extreme starbursts in the outskirts of HAE density peaks

“…However, the abundance and birthplace of SMGs rely on the evolutionary stage of galaxy protoclusters and how massive galaxies form in and around the protoclusters Cooke et al 2019;Shi et al 2020). On the other hand, large-scale environment is reported to play a key role in setting of the circumgalactic medium (CGM) angular momentum that governs gas infall and star formation in a galaxy (Wang et al 2021;Lu et al 2021). Therefore, mapping SMGs in and around the high-𝑧 protoclusters of galaxies is strongly demanded to uncover where and how extreme starbursts take place in the densest large-scale structures, and shed light on how massive galaxies form in the overdense environments (Bahé et al 2017;Bassini et al 2020;Lim et al 2021).…”