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Record 1 of 7037
Imaging the host galaxies of high-redshift radio-quiet QSOs
External Online Source: doi:10.1086/175199
Author and Affiliation:
Lowenthal, James D.(Johns Hopkins Univ., Baltimore, MD, United States)
Heckman, Timothy M.(Johns Hopkins Univ., Baltimore, MD, United States)
Lehnert, Matthew, D.(Institute for Geophysics and Planetary Physics, Livermore, CA, United States)
Elias, J. H.(National Optical Astronomical Observatories, Tucson, AZ, United States)
Abstract: We present new deep K-band and optical images of four radio-quiet QSOs at z approximately = 1 and six radio-quiet QSOs at z approximately = 2.5, as well as optical images only of six more at z approximately = 2.5. We have examined the images carefully for evidence of extended 'fuzz' from any putative QSO host galaxy. None of the z approximately = 2.5 QSOs shows any extended emission, and only two of the z approximately = 1 QSOs show marginal evidence for extended emission. Our 3 sigma detection limits in the K images, m(sub K) approximately = 21 for an isolated source, would correspond approximately to an unevolved L(sup star) elliptical galaxy at z = 2.5 or 2-3 mag fainter than an L(sup star) elliptical at z = 1, although our limits on host galaxy light are weaker than this due to the difficulty of separating galaxy light from QSO light. We simulate simple models of disk and elliptical host galaxies, and find that the marginal emission around the two z approximately = 1 QSOs can be explained by disks or bulges that are approximately 1-2 mag brighter than an unevolved L(sup star) galaxy in one case and approximately 1.5-2.5 mag brighter than L(sub star) in the other. For two other z approximately = 1 QSOs, we have only upper limits (L approximately = L(sup star)). The hosts of the high-redshift sample must be no brighter than about 3 mag above an unevolved L(sup star) galaxy, and are at least 1 magnitude fainter than the hosts of radio-loud QSOs at the same redshift. If the easily detected K-band light surrounding a previous sample of otherwise similar but radio-loud QSOs is starlight, then it must evolve on timescales of greater than or approximately equal to 10(exp 8) yr (e.g., Chambers & Charlot 1990); therefore our non-detection of host galaxy fuzz around radio-quiet QSOs supports the view that high-redshift radio-quiet and radio-loud QSOs inhabit different host objects, rather than being single types of objects that turn their radio emission on and off over short timescales. This is consistent with the general trend at low redshifts that radio-loud QSOs are found in giant elliptical galaxies while radio-quiet QSOs are found in less luminous disk galaxies. It also suggests that the processes responsible for the spectacular properties of radio-loud AGNs at high redshifts might not be generally relevent to the (far more numerous) radio-quiet population.
Publication Date: Feb 01, 1995
Document ID:
(Acquired Dec 28, 1995)
Accession Number: 95A76298
Subject Category: ASTROPHYSICS
Document Type: Journal Article
Publication Information: The Astrophysical Journal, Part 1 (ISSN 0004-637X); 439; 2; p. 588-589
Publisher Information: United States
Contract/Grant/Task Num: W-7405-ENG-48; NAG5-26555
Financial Sponsor: NASA; United States
Organization Source: NASA; Washington, DC, United States
NASA Goddard Space Flight Center; Greenbelt, MD, United States
Description: 11p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
Imprint And Other Notes: The Astrophysical Journal, Part 1 vol. 439, no. 2 p. 588-589 February 1, 1995
Miscellaneous Notes: Research sponsored by NASA
Availability Source: Other Sources
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