Revealing H I gas in emission and absorption on pc to kpc scales in a galaxy at z similar to 0.017

N. Gupta*, R. Srianand, J. S. Farnes, Y. Pidopryhora, M. Vivek, Z. Paragi, P. Noterdaeme, T. Oosterloo, P. Petitjean

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

We present a detailed study of the quasar-galaxy pair: J1243+4043-UGC 07904. The sight line of the background quasar (z(q) = 1.5266) passes through a region of the galaxy (z(g) = 0.0169) at an impact parameter of 6.9 kpc with high metallicity (0.5 Z(circle dot)) and negligible dust extinction. We detect H I 21-cm absorption from the foreground galaxy at arcsecond and milliarcsecond scales. For typical cold neutral medium (CNM) temperatures in the Milky Way, this 21-cm absorber can be classified as a damped Ly alpha absorber (DLA). We infer the harmonic mean spin temperature of the gas to be similar to 400K and for a simple two-phase medium we estimate the CNM fraction to be f(CNM) = 0.27. This is remarkably consistent with the CNM fraction observed in the Galaxy and less than that of high-redshift DLAs. The quasar exhibits a core-jet morphology on milliarcsecond scales, corresponding to an overall extent of similar to 9 pc at z(g). We show that the size of CNM absorbing clouds associated with the foreground galaxy is >5 pc and they may be part of cold gas structures that extend beyond similar to 35 pc. Interestingly, the rotation measure of quasar J1243+ 4043 is higher than any other source in samples of quasars with high-z DLAs. However, we do not find any detectable differences in rotation measures and polarization fraction of sight lines with or without high-z (z >= 2) DLAs or low-z (z

Original languageEnglish
Pages (from-to)2432-2445
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Volume476
Issue number2
DOIs
Publication statusPublished - May-2018

Keywords

  • galaxies: individual: UGC07904, IC 3723, IC 3726
  • galaxies: magnetic fields
  • quasars: absorption lines
  • quasars: individual: SDSS J124357.15+404346.5
  • DIGITAL SKY SURVEY
  • LY-ALPHA SYSTEMS
  • 21 CM ABSORPTION
  • STAR-FORMATION HISTORY
  • SPIN TEMPERATURE
  • HIGH-REDSHIFT
  • 21-CM ABSORPTION
  • CENTIMETER ABSORPTION
  • INTERSTELLAR-MEDIUM
  • FORMING GALAXIES

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