THE LYMAN ALPHA REFERENCE SAMPLE. V. THE IMPACT OF NEUTRAL ISM KINEMATICS AND GEOMETRY ON Lyα ESCAPE

Thøger E. Rivera-Thorsen, Matthew Hayes, Göran Östlin, Florent Duval, Ivana Orlitová, Anne Verhamme, J. Miguel Mas-Hesse, Daniel Schaerer, John M. Cannon, Héctor Otí-Floranes, Andreas Sandberg, Lucia Guaita, Angela Adamo, Hakim Atek, E. Christian Herenz, Daniel Kunth, Peter Laursen, Jens Melinder

Resultado de la investigación: Contribución a una revistaArtículorevisión exhaustiva

64 Citas (Scopus)

Resumen

We present high-resolution far-UV spectroscopy of the 14 galaxies of the Lyα 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 Lyα 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 Lyα 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 Lyα radiative transfer and escape. Lyα escape in our sample coincides with a maximum velocity-binned covering fraction of ≲0.9 and bulk outflow velocities of 50 km s-1, although a number of galaxies show these characteristics and yet little or no Lyα escape. We find that Lyα 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 Hα equivalent width and maximum velocity-binned covering factor, and propose a heuristic explanatory model.

Idioma originalInglés
Número de artículo14
PublicaciónAstrophysical Journal
Volumen805
N.º1
DOI
EstadoPublicada - 20 may 2015
Publicado de forma externa

Áreas temáticas de ASJC Scopus

  • Astronomía y astrofísica
  • Ciencias planetarias y espacial

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