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arXiv · 2001.10558

Solar-Metallicity Gas in the Extended Halo of a Galaxy at $z \sim 0.12$

Jayadev Pradeep·Sriram Sankar·T. M. Umasree·Anand Narayanan·Vikram Khaire·Matthew Gebhardt·Sameer·Jane C. Charlton
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Abstract

We present the detection and analysis of a weak low-ionization absorber at $z = 0.12122$ along the blazar sightline PG~$1424+240$, using spectroscopic data from both $HST$/COS and STIS. The absorber is a weak Mg II analogue, with incidence of weak C II and Si II, along with multi-component C IV and O VI. The low ions are tracing a dense ($n_{H} \sim 10^{-3}$ cm$^{-3}$) parsec scale cloud of solar or higher metallicity. The kinematically coincident higher ions are either from a more diffuse ($n_{H} \sim 10^{-5} - 10^{-4}$ cm$^{-3}$) photoionized phase of kiloparsec scale dimensions, or are tracing a warm (T $\sim 2 \times 10^{5}$ K) collisionally ionized transition temperature plasma layer. The absorber resides in a galaxy overdense region, with 18 luminous ($> L^*$) galaxies within a projected radius of $5$ Mpc and $750$ km s$^{-1}$ of the absorber. The multi-phase properties, high metallicity and proximity to a $1.4$ $L^*$ galaxy, at $\rho \sim 200$ kpc and $|\Delta v| = 11$ km s$^{-1}$ separation, favors the possibility of the absorption tracing circumgalactic gas. The absorber serves as an example of weak Mg II - O VI systems as a means to study multiphase high velocity clouds in external galaxies.

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Jayadev Pradeep, Sriram Sankar, T. M. Umasree, Anand Narayanan, Vikram Khaire, Matthew Gebhardt, Sameer, Jane C. Charlton. 2020-01-28. Solar-Metallicity Gas in the Extended Halo of a Galaxy at $z \sim 0.12$. https://doi.org/10.1093/mnras/staa184

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