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Intergalactic Transmission and its Impact on the Ly{\alpha} Line
Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
2011 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 728, no 1, 52- p.Article in journal (Other (popular science, discussion, etc.)) Published
Abstract [en]

We study the intergalactic transmission of radiation in the vicinity of the Ly{\alpha} wavelength. Simulating sightlines through the intergalactic medium (IGM) in detailed cosmological hydrosimulations, the impact of the IGM on the shape of the line profile from Ly{\alpha} emitting galaxies at redshifts 2.5 to 6.5 is investigated. In particular we show that taking into account the correlation of the density and velocity fields of the IGM with the galaxies, the blue part of the spectrum may be appreciably reduced, even at relatively low redshifts. This may in some cases provide an alternative to the often-invoked outflow scenario, although it is concluded that this model is still a plausible explanation of the many asymmetric Ly{\alpha} profiles observed. Applying the calculated wavelength dependent transmission to simulated spectra from Ly{\alpha} emitting galaxies, we derive the fraction of photons that are lost in the IGM, in addition to what is absorbed internally in the galaxies due to dust. Moreover, by comparing the calculated transmission of radiation blueward of the Ly{\alpha} line, the total optical depth to Thomson scattering of cosmic microwave background, with corresponding observations, we are able to constrain the epoch when the Universe was reionized to z <~ 8.5.

Place, publisher, year, edition, pages
2011. Vol. 728, no 1, 52- p.
Keyword [en]
Astrophysics, Cosmology, Extragalactic Astrophysics
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:su:diva-52830DOI: 10.1088/0004-637X/728/1/52ISI: 000286655500052OAI: diva2:389182
authorCount :3Available from: 2011-01-18 Created: 2011-01-18 Last updated: 2011-12-29Bibliographically approved

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Laursen, Peter
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Department of AstronomyThe Oskar Klein Centre for Cosmo Particle Physics (OKC)
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