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X-ray spectra of a complete sample of extragalactic core-dominated radio sourcesWe present ROSAT soft X-ray spectra for the members of a complete sample of 13 core-dominated, flat radio spectrum sources. The sample comprises all radio sources from a flux-limited radio catalog (S(sub 5GHz) greater than 1 Jy; Kuehr et al. 1981) which are north of delta = 70 deg, at galactic latitudes b greater than 10 deg, and have a flat radio spectrum between 1.4 and 5 GHz (alpha(sub r) less than 0.5; f approximately nu(sup -alpha)). The sources have already undergone much study at radio and optical wavelengths and are classified in broad terms as quasars (8 sources) and BL Lac objects (5 sources). We find mean X-ray power-law energy indices of alpha(sub x) = 0.59 +/- 0.19 for the quasars and 1.36 +/- 0.27 for the BL Lac objects (68% confidence range for two parameters of interest as determined by a maximum likelihood method), supporting earlier Einstein Observatory results for heterogeneous samples of sources (Worrall & Wilkes 1990). A non-zero dispersion on alpha(sub x) is found for both the quasars and the BL Lac objects. When we incorporate published radio, mm, and optical measurements and compare the X-ray and broad-band spectral indices alpha(sub x), alpha(sub rx), alpha(sub mm,x), and alpha(sub ox), the most obvious difference between the quasar and BL Lac subsamples lies within the X-ray band. We have fitted the multi-wavelength data to inhomogeneous synchotron-self-Compton models and find that, for the BL Lac objects with steep X-ray spectra, synchotron emission can account for the radio to soft X-ray measurements, whereas the BL Lac objects with hard X-ray spectra and the quasars require significant Compton emission to model the spectral flattening indicated by alpha(sub x) less than alpha(sub ox).
Document ID
19950057023
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Brunner, H.
(Astronomisches Institut der Universitaet Tuebingen, Tuebingen, Germany)
Lamer, G.
(Astronomisches Institut der Universitaet Tuebingen, Tuebingen, Germany)
Worrall, D. M.
(Harvard-Smithsonian Center for Astrophysics, Cambridge, MA United States)
Staubert, R.
(Astronomisches Institut der Universitaet Tuebingen, Tuebingen, Germany)
Date Acquired
August 16, 2013
Publication Date
July 10, 1994
Publication Information
Publication: Astronomy and Astrophysics
Volume: 287
Issue: 2
ISSN: 0004-6361
Subject Category
Astronomy
Accession Number
95A88622
Funding Number(s)
CONTRACT_GRANT: NAG5-1724
CONTRACT_GRANT: NAG5-1882
Distribution Limits
Public
Copyright
Other

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