Journal article
THE LYMAN ALPHA REFERENCE SAMPLE V. THE IMPACT OF NEUTRAL ISM KINEMATICS AND GEOMETRY ON Lyα ESCAPE
The Astrophysical journal, Vol.805(1), pp.1-26
05/20/2015
DOI: 10.1088/0004-637X/805/1/14
Abstract
We present high-resolution far-UV spectroscopy of the 14 galaxies of the Ly alpha Reference Sample; a sample of strongly star-forming galaxies at low redshifts (0.028 < z < 0.18). We compare the derived properties to global properties derived from multi-band imaging and 21 cm H I interferometry and single-dish observations, as well as archival optical SDSS spectra. Besides the Ly alpha line, the spectra contain a number of metal absorption features allowing us to probe the kinematics of the neutral ISM and evaluate the optical depth and and covering fraction of the neutral medium as a function of line of sight velocity. Furthermore, we show how this, in combination with the precise determination of systemic velocity and good Ly alpha spectra, can be used to distinguish a model in which separate clumps together fully cover the background source, from the "picket fence" model named by Heckman et al. We find that no one single effect dominates in governing Ly alpha radiative transfer and escape. Ly alpha escape in our sample coincides with a maximum velocity-binned covering fraction of less than or similar to 0.9 and bulk outflow velocities of greater than or similar to 50 km s(-1), although a number of galaxies show these characteristics and yet little or no Ly alpha escape. We find that Ly alpha peak velocities, where available, are not consistent with a strong backscattered component, but rather with a simpler model of an intrinsic emission line overlaid by a blueshifted absorption profile from the outflowing wind. Finally, we find a strong anticorrelation between H alpha equivalent width and maximum velocity-binned covering factor, and propose a heuristic explanatory model.
Details
- Title: Subtitle
- THE LYMAN ALPHA REFERENCE SAMPLE V. THE IMPACT OF NEUTRAL ISM KINEMATICS AND GEOMETRY ON Lyα ESCAPE
- Creators
- Thoger E. Rivera-Thorsen - Stockholm UniversityMatthew Hayes - Stockholm UniversityGoran Ostlin - Stockholm UniversityFlorent Duval - Stockholm UniversityIvana Orlitova - Czech Academy of Sciences, Astronomical InstituteAnne Verhamme - University of GenevaJ. Miguel Mas-Hesse - CSIC, INTA, Ctr Astrobiol, Dept Astrofis, E-28691 Villanueva De La Canada, SpainDaniel Schaerer - Université de ToulouseJohn M. Cannon - Macalester CollegeHector Oti-Floranes - Universidad Nacional Autónoma de MéxicoAndreas Sandberg - Stockholm UniversityLucia Guaita - Astronomical Observatory of RomeAngela Adamo - Stockholm UniversityHakim Atek - École Polytechnique Fédérale de LausanneE. Christian Herenz - Leibniz Institute for Astrophysics PotsdamDaniel Kunth - Institut d'Astrophysique de ParisPeter Laursen - University of CopenhagenJens Melinder - Stockholm University
- Resource Type
- Journal article
- Publication Details
- The Astrophysical journal, Vol.805(1), pp.1-26
- Publisher
- Iop Publishing Ltd
- DOI
- 10.1088/0004-637X/805/1/14
- ISSN
- 0004-637X
- eISSN
- 1538-4357
- Number of pages
- 26
- Grant note
- postdoctoral UNAM grant European Research Council (ERC); Spanish Government Swedish National Space Board (SNSB); Swedish National Space Agency (SNSA) Catedra CONACyT para Jovenes Investigadores GACR 14-20666 P / Czech Science Foundation; Grant Agency of the Czech Republic Vetenskapsradet; Swedish Research Council Centre National d'Etudes Spatiales (CNES); Centre National D'etudes Spatiales EGGS-278202 / ERC-StG grant; European Research Council (ERC) Swedish Research Council DNRF
- Language
- English
- Date published
- 05/20/2015
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984627186002771