Solar-metallicity gas in the extended halo of a galaxy at z ∼ 0.12

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

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


We present the detection and analysis of a weak low-ionization absorber at z = 0.121 22 along the sightline of the blazar PG 1424+240, using spectroscopic data from both HST/COS and STIS. The absorber is a weak Mg II analogue, with an incidence of weak C II and Si II, along with multicomponent C IV and O VI. The low ions are tracing a dense (nH ∼ 10−3 cm−3) parsec-scale cloud of solar or higher metallicity. The kinematically coincident higher ions are either from a more diffuse (nH ∼ 10−5–10−4 cm−3) photoionized phase of kiloparsec-scale dimensions or are tracing a warm (T ∼ 2 × 105 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 velocity of 750 km s−1. The multiphase properties, high metallicity, and proximity to a 1.4L galaxy, at ρ ∼ 200 kpc and separation |v| = 11 km s−1, favour 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.

Original languageEnglish (US)
Pages (from-to)250-266
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - Mar 1 2020

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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