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X-ray intensity and spectral variations in the BL Lac sources H2155-304 and PKS0548-322The results from the X-ray observations of two BL Lacertae objects, H2155-304 and PKS0548-322, are presented. The observations were carried out with the HEAO-1 A2 Low Energy Detectors, the High Resolution Imager, and the Monitor Proportional Counter aboard the Einstein Observatory. Correlated X-ray intensity variations of about 20 percent in the 0.15-3.5 keV energy band and about 40 percent in the 1.5-10 keV energy band are observed in H2155-304 over a period of about 8 hr. A factor of two change in the intensity of PKS0548-322 in the 3.5-10 keV energy interval is also detected over a time interval of 1 hr. Variations in the X-ray intensity over a timescale of months and the hardening of the spectrum with increasing intensity are seen in the HEAO-1 A2 data on H2155-304. The shortest observed timescale for the variability is used to derive an upper limit on the mass of the central accreting source in the two BL Lac objects studied here.
Document ID
19870060818
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Agrawal, P. C.
(Tata Inst. of Fundamental Research Bombay, India)
Singh, K. P.
(Tata Institute of Fundamental Research Bombay, India)
Riegler, G. R.
(California Institute of Technology Jet Propulsion Laboratory, Pasadena, United States)
Date Acquired
August 13, 2013
Publication Date
July 15, 1987
Publication Information
Publication: Royal Astronomical Society, Monthly Notices
Volume: 227
ISSN: 0035-8711
Subject Category
Astronomy
Accession Number
87A48092
Distribution Limits
Public
Copyright
Other

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