The Cosmic Ultraviolet Baryon Survey (CUBS). II. Discovery of an H₂-bearing DLA in the Vicinity of an Early-type Galaxy at z = 0.576*

Abstract

We report the serendipitous detection of an H2-bearing damped Lyα absorber at z = 0.576 in the spectrum of the QSO J0111–0316 in the Cosmic Ultraviolet Baryon Survey. Spectroscopic observations from Hubble Space Telescope-COS in the far-ultraviolet reveal a damped absorber with log[N(H i)/cm−2] = 20.1 ± 0.2 and log[N(H2)/cm−2] . The diffuse molecular gas is found in two velocity components separated by Δ ν ≈ 60 km s−1, with >99.9% of the total H2 column density concentrated in one component. At a metallicity of ≈50% of solar, there is evidence for Fe enhancement and dust depletion, with a dust-to-gas ratio κ O ≈ 0.4. A galaxy redshift survey conducted with IMACS and LDSS-3C on Magellan reveals an overdensity of nine galaxies at projected distance d ≤ 600 proper kpc (pkpc) and line-of-sight velocity offset Δ ν g ≤ 300 km s−1 from the absorber. The closest is a massive, early-type galaxy at d = 41 pkpc that contains ≈70% of the total stellar mass identified at d ≤ 310 pkpc of the H2 absorber. The close proximity of the H2-bearing gas to the quiescent galaxy and the Fe-enhanced chemical abundance pattern of the absorber suggest a physical connection, in contrast to a picture in which DLAs are primarily associated with gas-rich dwarfs. This case study illustrates that deep galaxy redshift surveys are needed to gain insight into the diverse environments that host dense and potentially star-forming gas.

The Cosmic Ultraviolet Baryon Survey (CUBS) V: on the thermodynamic properties of the cool circumgalactic medium at z ≲ 1

“…Previous studies have shown that the CGM is multiphase, including cold molecular gas, cool photoionized gas, warm-hot collisionallyionized gas, and hot X-ray/𝛾-ray emitting plasma (e.g., Savage et al 2014;Werk et al 2016;Bogdán et al 2017;Li et al 2018;Das et al 2020;Boettcher et al 2021;Karwin et al 2021). Theoretically, the volume-filling hot medium is formed via virial shocks and galactic feedback (e.g., Cen & Ostriker 2006), while lower temperature gas is confined within this volume-filling hot medium in the forms of clouds or filaments.…”

MALS SALT-NOT survey of MIR-selected powerful radio-bright AGN at 0

“…Despite the availability of large samples of intervening DLAs (e.g., Noterdaeme et al 2009;Parks et al 2018) and the fact that they trace the bulk of neutral hydrogen in the Universe (Wolfe et al 2005), the detected DLAs show little dust (e.g. Murphy & Liske 2004) and only a small fraction exhibit the presence of molecular hydrogen (Petitjean et al 2000;Ledoux et al 2003;Noterdaeme et al 2008;Srianand et al 2012;Noterdaeme et al 2015;Muzahid et al 2015;Balashev & Noterdaeme 2018;Zahedy et al 2020;Boettcher et al 2021).…”

Discovery of a damped Ly$α$ absorber originating in a spectacular interacting dwarf galaxy pair at $z = 0.026$

“…We refer the reader to Chen et al (2020) for a description of the absorption-line observations of J2339-5523 from the Cosmic Origins Spectrograph (COS) on HST (𝜆 = 1100-1800 Å, spectral resolution FWHM ≈ 20 km s −1 ) and the Magellan Inamori Kyocera Echelle (MIKE) spectrograph on Magellan-Clay (𝜆 = 3200-9200 Å, FWHM ≈ 8 km s −1 ). We use Voigt profile fitting to determine the velocity (𝑣), Doppler parameter (𝑏), and column density (𝑁) of the atomic and ionic transitions associated with the DLA using a grid search as described in §3 of Boettcher et al (2021). The COS wavelength calibration is sufficiently uncertain that we allow small variations within 𝛿𝑣 = ±5 km s −1 for low and intermediate ions in COS with respect to Ca II𝜆𝜆3934, 3969 in MIKE.…”