Lyman α absorption beyond the disc of simulated spiral galaxies

Bernhard Röttgers, Thorsten Naab, Miha Cernetic, Romeel Davé, Guinevere Kauffmann, Sanchayeeta Borthakur, Horst Foidl

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

We present an analysis of the origin and properties of the circumgalactic medium (CGM) in a suite of 11 cosmological zoom simulations resembling present-day spiral galaxies. On average the galaxies retain about 50 per cent of the cosmic fraction in baryons, almost equally divided into disc (interstellar medium) gas, cool CGM gas and warm-hot CGM gas. At radii smaller than 50 kpc the CGM is dominated by recycled warm-hot gas injected from the central galaxy, while at larger radii it is dominated by cool gas accreted on to the halo. The recycled gas typically accounts for one-third of the CGM mass. We introduce the novel publicly available analysis tool pygad to compute ion abundances and mock absorption spectra. For Lyman α absorption, we find good agreement of the simulated equivalent width (EW) distribution and observations out to large radii. Disc galaxies with quiescent assembly histories show significantly more absorption along the disc major axis. By comparing the EW and H i column densities, we find that CGM Lyman α absorbers are best represented by an effective line width b ≈ 50-70 km s-1 that increases mildly with halo mass, larger than typically assumed.

Original languageEnglish (US)
Pages (from-to)152-168
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Volume496
Issue number1
DOIs
StatePublished - Jun 11 2020

Keywords

  • Galaxy: formation
  • circumstellar matter
  • line: profiles
  • quasars: absorption lines

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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