Gas around galaxy haloes - III: hydrogen absorption signatures around galaxies and QSOs in the Sherwood simulation suite

Abstract

Modern theories of galaxy formation predict that galaxies impact on their gaseous surroundings, playing the fundamental role of regulating the amount of gas converted into stars. While star-forming galaxies are believed to provide feedback through galactic winds, Quasi-Stellar Objects (QSOs) are believed instead to provide feedback through the heat generated by accretion onto a central supermassive black hole. A quantitative difference in the impact of feedback on the gaseous environments of starforming galaxies and QSOs has not been established through direct observations. Using the Sherwood cosmological simulations, we demonstrate that measurements of neutral hydrogen in the vicinity of star-forming galaxies and QSOs during the era of peak galaxy formation show excess Lyman-α absorption extending up to comoving radii of ∼ 150 kpc for star-forming galaxies and 300−700 kpc for QSOs. Simulations including supernovae-driven winds account for the absorption around star-forming galaxies but not QSOs.

simba: the average properties of the circumgalactic medium of 2 ≤ z ≤ 3 quasars are determined primarily by stellar feedback

“…Directly related to the HI content of CGM and IGM surrounding galaxies, the average Lyα absorption profile is another very well-studied statistic. Large-volume hydrodynamic simulations with various feedback implementations have been employed in several works (Kollmeier et al 2003(Kollmeier et al , 2006Rakic et al 2012Rakic et al , 2013Meiksin et al 2014Meiksin et al , 2015Meiksin et al , 2017Turner et al 2017, see also Chung et al 2019 for a related study with zoom-in simulations) aiming at reproducing measurements of the Lyα flux decrement around LBGs (Adelberger et al 2003(Adelberger et al , 2005Steidel et al 2010;Crighton et al 2011;Rakic et al 2012;Turner et al 2014) and/or QSOs (Prochaska et al 2013b). Except for data points within the virial radius of foreground objects, these observations were generally matched by the simulations.…”

“…The majority of past numerical studies of the CGM were mainly concerned with reproducing the covering factor of optically thick absorbers around galaxies and QSOs in the redshift range z ∼ 2 − 3. While recent simulations (Ceverino et al 2012;Dekel et al 2013;Shen et al 2013;Meiksin et al 2015;Suresh et al 2015;Meiksin et al 2017;Suresh et al 2019) were able to broadly reproduce Rudie et al (2012) measurements of this quantity around galaxies, the high covering factor observed around QSOs by Prochaska et al (2013b) proved to be harder to reproduce (Fumagalli et al 2014;Faucher-Giguère et al 2015). Later, Faucher-Giguère et al (2016) was able to recover such measurements with the FIRE zoom-in simulations (Hopkins et al 2014), which included only stellar feedback, arguing that high resolution was a crucial element to obtain this result.…”

“…Later, systematic studies of Lyα absorbers with high optical depth in the IGM at 2.6 z 3.3 revealed overdensities in the cosmic web on scales ∼ 10−20Mpc, thus constraining structure formation models (Cai et al 2016(Cai et al , 2017. More recently, Lyα forest tomography techniques (Pichon et al 2001;Caucci et al 2008;Gallerani et al 2011;Stark et al 2015a,b;Lee et al 2016a;Horowitz et al 2019) enabled the 3D reconstruction of the cosmic web thanks to various surveys (e.g., CLAMATO Lee et al 2014, LATIS Newman et al 2020, and eBOSS Ravoux et al 2020, whereby Lyα absorption in spectra of z ∼ 2−3 galaxies and quasars is utilised as a probe of diffuse gas in the intervening IGM, and around foreground star-forming galaxies and protoclusters (Lee et al 2016b; see also Mukae et al 2019 andMomose et al 2020 for related studies).…”

“…Except for data points within the virial radius of foreground objects, these observations were generally matched by the simulations. Using the Sherwood (Bolton et al 2017) suite of simulations, Meiksin et al (2017) suggested that the discrepancy with observations close to the foreground objects could be mitigated by stronger stellar feedback, while Turner et al (2017) found that the Lyα optical depth given by the EAGLE simulations depends only weakly on the stellar feedback model. More recently, Sorini et al (2018) expanded this line of research by comparing the predictions of different cosmological simulations with several observations of Lyα transmission at redshift z ∼ 2 − 3 around QSOs (Font-Ribera et al 2013;Prochaska et al 2013b), LBGs (Adelberger et al 2003(Adelberger et al , 2005Crighton et al 2011;Turner et al 2014), and DLAs (Font-Ribera et al 2012;Rubin et al 2015), covering three decades of distance (10 kpc − 10 Mpc) around such objects (see also Sorini 2017).…”

A comparison of observed and simulated absorption from H i, C iv, and Si ivaroundz ≈ 2 star-forming galaxies suggests redshift–space distortions are due to inflows

“…Faucher-Giguère et al (2016) and Meiksin, Bolton & Puchwein (2017) also concluded that simulations employing strong feedback can reproduce the observations. For metal-line absorption, z < 1 O VI observations from Tumlinson et al (2011) and Prochaska et al (2011) have proven challenging for simulations to reproduce (Suresh et al 2017;Oppenheimer et al 2016), though the correspondence is better for low ions, perhaps due to a paucity of hot gas in the models (Hummels et al 2013;Ford et al 2016).…”