Open AccessPKS 0405−385: The Smallest Radio Quasar?
Author(s) -
Lucyna KedzioraChudczer,
D. L. Jauncey,
M. H. Wieringa,
M. A. Walker,
G. D. Nicolson,
J. E. Reynolds,
A. K. Tzioumis
Publication year - 1997
Publication title -
the astrophysical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.376
H-Index - 489
eISSN - 1538-4357
pISSN - 0004-637X
DOI - 10.1086/311001
Subject(s) - quasar , physics , brightness , synchrotron , astrophysics , flux (metallurgy) , brightness temperature , lorentz factor , limit (mathematics) , inverse , magnitude (astronomy) , astronomy , lorentz transformation , optics , galaxy , classical mechanics , metallurgy , mathematical analysis , mathematics , geometry , materials science
We have observed profound variability in the radio flux density of the quasarPKS 0405-385 on timescales of less than an hour; this is unprecedented amongstextragalactic sources. If intrinsic to the source, these variations would implya brightness temperature 10^21 K, some nine orders of magnitude larger than theinverse Compton limit for a static synchrotron source, and still a milliontimes greater than can be accommodated with bulk relativistic motion at aLorentz factor equal to 10. The variability is intermittent with episodeslasting a few weeks to months. Our data can be explained most sensibly as interstellar scintillation of asource component which is < 5 microarcsec in size - a source size which impliesa brightness temperature > 5 times 10^14 K, still far above the inverse Comptonlimit. Simply interpreted as a steady, relativistically beamed synchrotronsource, this would imply a bulk Lorentz factor 1000.Comment: 13 pages, 3 PostScript figures, to appear in ApJ
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