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          Institute: MPI für extraterrestrische Physik     Collection: Infrared and Submillimeter Astronomy     Display Documents

ID: 10684.0, MPI für extraterrestrische Physik / Infrared and Submillimeter Astronomy
Investigating the central engine of ultraluminous infrared galaxies: near-infrared imaging
Authors:Davies, R. I.; Burston, A.; Ward, M. J.
Date of Publication (YYYY-MM-DD):2002-01-11
Title of Journal:Monthly Notices of the Royal Astronomical Society
Journal Abbrev.:Mon. Not. R. Astron. Soc.
Issue / Number:2
Start Page:367
End Page:376
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:We present 0.5-arcsec-resolution near-infrared images of six ultraluminous infrared galaxies with known redshifts. Six of the eight bright nuclei are resolved on kiloparsec scales, suggesting that there is significant circumnuclear star formation or close progenitor nuclei. At this spatial resolution, the nuclei have very red colours that cannot in general be reproduced by reddening stellar light, but require an additional component of hot dust emission. In five of the six primary nuclei more than 20 per cent of the K-band continuum originates in hot dust, but the temperature cannot be determined by JHK broad-band colours alone. Comparison with the spectral shapes, however, does allow the temperature to be constrained, and we find in every case that it is at the upper end of the permissible range, greater than or similar to 1000 K. This does not necessarily imply that there is an active galactic nucleus present, since there is evidence that stellar processes can also generate dust this hot via stochastic heating of small grains. The quantities of hot dust we have found here can make up to 0.5-mag difference to the K-band magnitude even at z similar to 1, with implications for observations and population synthesis models of higher-redshift objects. Observations in the L or M bands, where hot dust is most important at z similar to 1, could help to discriminate between models of dusty starbursts and ellipticals.
Free Keywords:galaxies : active; galaxies : interactions; galaxies : nuclei; galaxies : Seyfert; galaxies : starburst; infrared : galaxies
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für extraterrestrische Physik
External Affiliations:Max Planck Inst Extraterr Phys, Postfach 1312, D-85741; Garching, Germany; Max Planck Inst Extraterr Phys, D-85741 Garching, Germany; Univ Leicester, Dept Astron, Leicester LE1 7RH, Leics, England
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