Characterizing the circum-galactic medium of damped Lyman-α absorbing galaxies

Abstract

Gas flows in and out of galaxies through their circumgalactic medium (CGM) are poorly constrained and direct observations of this faint, diffuse medium remain challenging. We use a sample of five z ∼ 1-2 galaxy counterparts to Damped Lyman-α Absorbers (DLAs) to combine data on cold gas, metals and stellar content of the same galaxies. We present new HST/WFC3 imaging of these fields in 3-5 broadband filters and characterise the stellar properties of the host galaxies. By fitting the spectral energy distribution, we measure their stellar masses to be in the range of log(M * /M ) ∼ 9.1−10.7. Combining these with IFU observations, we find a large spread of baryon fractions inside the host galaxies, between 7 and 100 percent. Similarly, we find gas fractions between 3 and 56 percent. Given their star formation rates, these objects lie on the expected main sequence of galaxies. Emission line metallicities indicate they are consistent with the mass-metallicity relation for DLAs. We also report an apparent anti-correlation between the stellar masses and N(H i), which could be due to a dust bias effect or lower column density systems tracing more massive galaxies. We present new ALMA observations of one of the targets leading to a molecular gas mass of log(M mol /M ) < 9.89. We also investigate the morphology of the DLA counterparts and find that most of the galaxies show a clumpy structure and suggest ongoing tidal interaction. Thanks to our high spatial resolution HST data, we gain new insights in the structural complexity of the CGM.

MUSE-ALMA haloes V: physical properties and environment of z ≤ 1.4 H i quasar absorbers

“…In Fig.8 we present the H i column density versus impact parameter. Studies so far, mostly for high H i column density absorbers (Krogager et al 2017;Augustin et al 2018), showed an anti-correlation between N(H i) and impact parameter, which is also reproduced by the OWLS hydrodynamical simulations (Rahmati & Schaye 2014): the larger the N(H i) column densities the smaller the impact parameter. Including all galaxies associated with absorbers, we are retrieving this relation also at lower H i column densities (from 10 18 to 10 21.7 cm −2 ).…”

The nature of strong H i absorbers probed by cosmological simulations: satellite accretion and outflows

“…Similar conclusions were also reached with deep ground-based imaging of sub-DLA hosts, which suggest that these systems preferentially sample more luminous -and therefore more massive galaxies than DLAs (Meiring et al 2011). By measuring the stellar mass of the absorbing galaxies from matching spectral energy distribution galaxy templates to photometry, Augustin et al (2018) and Rhodin et al (2018) directly confirmed the apparent anti-correlation between the host's stellar mass and the H i column-density of the absorber. If real, this correlation is remarkable as we expect both high-and low column-density LOS to pass through a given galaxy.…”

Exploring galaxy dark matter haloes across redshifts with strong quasar absorbers

“…Moreover, this relation can be interpreted as a relation between DLA metallicity and host galaxy halo mass (Møller et al 2013), reflecting the known luminosity-selected galaxy mass-metallicity relation (Tremonti et al 2004;Maiolino et al 2008). By measuring the stellar masses of the host galaxies, we now know that DLAs indeed follow a mass-metallicity relation (Christensen et al 2014;Augustin et al 2018;Rhodin et al 2018).…”