Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published May 2015 | Published + Submitted
Journal Article Open

Properties of QSO Metal-line Absorption Systems at High Redshifts: Nature and Evolution of the Absorbers and New Evidence on Escape of Ionizing Radiation from Galaxies

Abstract

Using Voigt-profile-fitting procedures on Keck High Resolution Spectrograph spectra of nine QSOs, we identify 1099 C IV absorber components clumped in 201 systems outside the Lyman forest over 1.6 ≾ z ≾ 4.4. With associated Si IV, C II, Si II and N V where available, we investigate the bulk statistical and ionization properties of the components and systems and find no significant change in redshift for C IV and Si IV while C II, Si II and N V change substantially. The C IV components exhibit strong clustering, but no clustering is detected for systems on scales from 150 km s^(–1) out to 50,000 km s^(–1). We conclude that the clustering is due entirely to the peculiar velocities of gas present in the circumgalactic media of galaxies. Using specific combinations of ionic ratios, we compare our observations with model ionization predictions for absorbers exposed to the metagalactic ionizing radiation background augmented by proximity radiation from their associated galaxies and find that the generally accepted means of radiative escape by transparent channels from the internal star-forming sites is spectrally not viable for our stronger absorbers. We develop an active scenario based on runaway stars with resulting changes in the efflux of radiation that naturally enable the needed spectral convergence, and in turn provide empirical indicators of morphological evolution in the associated galaxies. Together with a coexisting population of relatively compact galaxies indicated by the weaker absorbers in our sample, the collective escape of radiation is sufficient to maintain the intergalactic medium ionized over the full range 1.9 < z ≾ 4.4.

Additional Information

© 2015 American Astronomical Society. Received 2003 June 12; accepted 2014 September 9; published 2015 May 11. Foremost, I want to acknowledge Wallace Sargent who passed away in 2012 October. He has been my best friend from the time we first worked together at Palomar exactly 41 years ago. A true gentleman, he excelled not only in science but also widely in many cultures. He inspired and helped me in countless ways and I am forever grateful to him. Also, we had great fun together. He is the founding worker of all in this paper (A.B.). We are grateful to the anonymous referees, whose advice improved this paper significantly. We are greatly indebted to Michael Rauch for generous provision of some of his QSO spectra which added much to our results; Tom Barlow for the initial data reduction; Robert Carswell for being so unstinting with his time for schooling, advice, and assistance for use of VPFIT; Francesco Haardt with Piero Madau for their great generosity over the years 1998–2014 in providing many new trial computations for the metagalactic background radiation and for very many greatly helpful discussions; Roderick Johnstone for enormous help, assistance, and advice in the use of Cloudy; Max Pettini for spending so much time on many clarifying discussions and for invaluable help and encouragement; Robin Catchpole for continuous patient discussion, advice, and encouragement and shared humor over many years; Michael Shull for a great many extremely illuminating, inspiring, and course-setting discussions and his trenchant critical reading of the manuscript; Sverre Aarseth for fundamental advice and extreme generosity and good will in providing the means for gravitational modeling and personally conducting the complex procedures; George Becker for long-standing serial advice and guidance; Gary Ferland for direct advice about Cloudy; Claus Leitherer for help and advice on the use of Starburst99; Robert Lupton for provision of a new facility within Supermongo; Roberto Abraham and Robert Simcoe for setting up analysis software and other assistance; Christopher Tout for much advice and assistance on stellar matters; and Floor van Leeuven for analytical help with Hipparcos runaway star material. We benefited from informative discussions with Cathie Clarke, Crystal Martin, David Valls-Gabaud, Samantha Rix, Paul Crowther, Martin Haehnelt, Andy Fabian, Robert Kennicutt, Maciej Hermanowicz, Stephen Smartt, Michael Irwin, George Efstathiou, Gerry Gilmore, and Michael Murphy among many others. We also thank the Keck Observatory staff for their assistance with the observations. Finally, we extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, the observations presented herein would not have been possible. A.B. gratefully acknowledges support from The Leverhulme Trust, the UK Particle Physics and Astronomy Research Council, and the ongoing wide-ranging support of the Institute of Astronomy. W.L.W.S was supported by NSF grants AST-9900733 and AST-0206067.

Attached Files

Published - 0067-0049_218_1_7.pdf

Submitted - 1410.3784v1.pdf

Files

1410.3784v1.pdf
Files (14.4 MB)
Name Size Download all
md5:a295fa341136427a8db1bd06daf7a07c
7.4 MB Preview Download
md5:ec046b417afb0b48a356de2efb1e1dd7
7.0 MB Preview Download

Additional details

Created:
August 22, 2023
Modified:
October 23, 2023