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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 606585.0, MPI für Astronomie / Publikationen_mpia
The nature of z ~ 2.3 Lyman-a emitters
Authors:Nilsson, K. K.; Östlin, G.; Møller, P.; Möller-Nilsson, O.; Tapken, C.; Freudling, W.; Fynbo, J. P. U.
Date of Publication (YYYY-MM-DD):2011
Journal Abbrev.:Astronomy and Astrophysics
Audience:Not Specified
Abstract / Description:We study the multi-wavelength properties of a set of 171 Lyα emitting candidates at redshift z = 2.25 found in the COSMOS field, with the aim of understanding the underlying stellar populations in the galaxies. We especially seek to understand what the dust contents, ages and stellar masses of the galaxies are, and how they relate to similar properties of Lyα emitters at other redshifts. The candidates here are shown to have different properties from those of Lyα emitters found at higher redshift, by fitting the spectral energy distributions (SEDs) using a Monte-Carlo Markov-Chain technique and including nebular emission in the spectra. The stellar masses, and possibly the dust contents, are higher, with stellar masses in the range log M∗ = 8.5-11.0 M&sun; and AV = 0.0-2.5 mag. Young population ages are well constrained, but the ages of older populations are typically unconstrained. In 15% of the galaxies only a single, young population of stars is observed. We show that the Lyα fluxes of the best fit galaxies are correlated with their dust properties, with higher dust extinction in Lyα faint galaxies. Testing for whether results derived from a light-weighted stack of objects correlate to those found when fitting individual objects we see that stellar masses are robust to stacking, but ages and especially dust extinctions are derived incorrectly from stacks. We conclude that the stellar properties of Lyα emitters at z = 2.25 are different from those at higher redshift and that they are diverse. Lyα selection appears to be tracing systematically different galaxies at different redshifts. Based on observations carried out at the European Southern Observatory (ESO) under prog. ID No. 084.A-0318(B).Tables 6 is only available in electronic form at <A href="http://www.aanda.org">http://www.aanda.org</A>
Free Keywords:cosmology: observations; galaxies: high-redshift
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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