Volume 522, November 2010
|Number of page(s)||5|
|Section||Cosmology (including clusters of galaxies)|
|Published online||27 October 2010|
Dust grain growth in the interstellar medium of 5 < z < 6.5 quasars
Scottish Universities Physics Alliance, Institute for Astronomy, University
of Edinburgh, Royal Observatory, Edinburgh, EH9
2 Spitzer Science Center, MC 314-6, California Institute of Technology, Pasadena, CA 91125, USA
3 Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
4 Department of Physics & Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1, Canada
Accepted: 28 June 2010
Aims. We investigate whether stellar dust sources i.e. asymptotic giant branch (AGB) stars and supernovae (SNe) can account for dust detected in 5 < z < 6.5 quasars (QSOs).
Methods. We calculate the required dust yields per AGB star and per SN using the dust masses of QSOs inferred from their millimeter emission and stellar masses approximated as the difference between the dynamical and the H2 gas masses of these objects.
Results. We find that AGB stars are not efficient enough to form dust in the majority of the z > 5 QSOs, whereas SNe may be able to account for dust in some QSOs. However, they require very high dust yields even for a top-heavy initial mass function.
Conclusions. This suggests additional non-stellar dust formation mechanism e.g. significant dust grain growth in the interstellar medium of at least three out of nine z > 5 QSOs. SNe (but not AGB stars) may deliver enough heavy elements to fuel this growth.
Key words: dust, extinction / galaxies: high-redshift / galaxies: ISM / submillimeter: galaxies / quasars: general
© ESO, 2010
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