Skip to main content

Research Repository

Advanced Search

Metal-enriched, subkiloparsec gas clumps in the circumgalactic medium of a faint z = 2.5 galaxy

Crighton, N.H.M.; Hennawi, J.F.; Simcoe, R.A.; Cooksey, K.L.; Murphy, M.T.; Fumagalli, M.; Prochaska, J.X.; Shanks, T.

Metal-enriched, subkiloparsec gas clumps in the circumgalactic medium of a faint z = 2.5 galaxy Thumbnail


Authors

N.H.M. Crighton

J.F. Hennawi

R.A. Simcoe

K.L. Cooksey

M.T. Murphy

J.X. Prochaska



Abstract

We report the serendipitous detection of a 0.2 L*, Lyα emitting galaxy at redshift 2.5 at an impact parameter of 50 kpc from a bright background QSO sightline. A high-resolution spectrum of the QSO reveals a partial Lyman-limit absorption system (NHi=1016.94±0.10 cm−2) with many associated metal absorption lines at the same redshift as the foreground galaxy. Using photoionization models that carefully treat measurement errors and marginalize over uncertainties in the shape and normalization of the ionizing radiation spectrum, we derive the total hydrogen column density NH=1019.4±0.3cm−2, and show that all the absorbing clouds are metal enriched, with Z = 0.1–0.6 Z⊙. These metallicities and the system's large velocity width (436 km s− 1) suggest the gas is produced by an outflowing wind. Using an expanding shell model we estimate a mass outflow rate of ∼5 M⊙ yr−1. Our photoionization model yields extremely small sizes (<100–500 pc) for the absorbing clouds, which we argue is typical of high column density absorbers in the circumgalactic medium (CGM). Given these small sizes and extreme kinematics, it is unclear how the clumps survive in the CGM without being destroyed by hydrodynamic instabilities. The small cloud sizes imply that even state-of-the-art cosmological simulations require more than a 1000-fold improvement in mass resolution to resolve the hydrodynamics relevant for cool gas in the CGM.

Citation

Crighton, N., Hennawi, J., Simcoe, R., Cooksey, K., Murphy, M., Fumagalli, M., …Shanks, T. (2015). Metal-enriched, subkiloparsec gas clumps in the circumgalactic medium of a faint z = 2.5 galaxy. Monthly Notices of the Royal Astronomical Society, 446(1), 18-37. https://doi.org/10.1093/mnras/stu2088

Journal Article Type Article
Acceptance Date Oct 6, 2014
Online Publication Date Nov 10, 2014
Publication Date Jan 1, 2015
Deposit Date Nov 17, 2014
Publicly Available Date Nov 18, 2014
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 446
Issue 1
Pages 18-37
DOI https://doi.org/10.1093/mnras/stu2088
Keywords Galaxies: haloes, Quasars: absorption lines.
Public URL https://durham-repository.worktribe.com/output/1450379
Related Public URLs http://adsabs.harvard.edu/abs/2015MNRAS.446...18C

Files

Published Journal Article (1.9 Mb)
PDF

Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.






You might also like



Downloadable Citations