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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 448239.0, MPI für Astronomie / Publikationen_mpia
GMASS ultradeep spectroscopy of galaxies at z ~ 2. IV. The variety of dust populations
Authors:Noll, S.; Pierini, D.; Cimatti, A.; Daddi, E.; Kurk, J. D.; Bolzonella, M.; Cassata, P.; Halliday, C.; Mignoli, M.; Pozzetti, L.; Renzini, A.; Berta, S.; Dickinson, M.; Franceschini, A.; Rodighiero, G.; Rosati, P.; Zamorani, G.
Date of Publication (YYYY-MM-DD):2009
Title of Journal:Astronomy and Astrophysics
Journal Abbrev.:A & A
Start Page:69
End Page:85
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:Aims. The properties of dust attenuation at rest-frame UV wavelengths are inferred from very high-quality FORS 2 spectra of 78 galaxies from the GMASS survey at redshift 1 < z < 2.5. These objects complement a previously investigated sample of 108 UV-luminous, intermediate-mass (i.e., with stellar masses 1010-1011 Msun) galaxies at similar redshifts, selected from the FDF spectroscopic survey, the K20 survey, and the GDDS. Detection of the broad absorption feature centred on about 2175 Å (``UV bump'') implies that the average UV extinction curve of a galaxy more closely resembles that of the Milky Way (MW) or the Large Magellanic Cloud (LMC), and differs from that of the Small Magellanic Cloud (SMC). Methods: The shape of the UV extinction curve is constrained by a parametric description of the rest-frame UV continuum with the support of a suite of models combining radiative transfer and stellar population synthesis. The UV bump is further characterised by fitting Lorentzian-like profiles. Results: Spectra exhibit a significant 2175 Å feature in at least 30% of the cases, especially those suffering from substantial reddening. If attenuation is dominated by dust ejected from the galaxy main body via galactic winds or more localised superwinds, UV extinction curves in-between those of the SMC and LMC characterise UV-luminous, intermediate-mass galaxies at 1 < z < 2.5. The fraction of galaxies with extinction curves differing from the SMC one increases, if more dust resides in the galactic plane or dust attenuation depends on stellar age. On average, the width of the manifested UV bumps is about 60% of the values typically measured along sightlines in the LMC and MW. This suggests the presence of dust similar to that found in the ``supergiant'' shell of ionised filaments LMC 2, close to 30 Dor. The presence of the carriers of the UV bump (probably organic carbon and amorphous silicates) at 1 < z < 2.5 argues for outflows from asymptotic giant branch (AGB) stars being copious then. Consistent with their higher star-formation rates, the GMASS galaxies with a manifested UV bump are more luminous at rest-frame 8 mum, where the emission is dominated by polycyclic aromatic hydrocarbons (also products of AGB stars). In addition, they exhibit larger equivalent widths for prominent
Free Keywords:galaxies: high-redshift; galaxies: starburst; galaxies: ISM; ISM: dust; extinction; ultraviolet: galaxies
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2009A%26A...499...69... [ID No:1]
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