Showing papers by "L. Maraschi published in 1992"
TL;DR: The physical conditions in the gamma-ray-emitting blazar 3C 279 are discussed in this article, where it is proposed that the gamma rays are produced in a relativistic jet via the synchrotron self-Compton mechanism.
Abstract: The physical conditions in the gamma-ray-emitting blazar 3C 279 are discussed. The requirement of transparency for gamma-rays, together with the observation of rapid variability, imply that the high-energy radiation is anisotropic. It is proposed that the gamma-rays are produced in a relativistic jet via the synchrotron self-Compton mechanism. The gamma-ray spectrum is the high-energy extension of the inverse Compton radiation responsible for the X-ray emission. It is softer than the X-ray spectrum, owing to upper cutoffs in the electron energy spectra along the jet. The same electrons are responsible for the low-frequency emission via synchrotron radiation. The expected correlation of variability at different frequencies is discussed. 38 refs.
946 citations
01 Mar 1992
TL;DR: The bright quasar Kaz 102, which lies in the vicinity of the North Ecliptic Pole, was monitored during the ROSAT All Sky Survey for 121.5 days from 1990 July 30 to 1991 January 25.
Abstract: The bright quasar Kaz 102, which lies in the vicinity of the North Ecliptic Pole, was monitored during the ROSAT All Sky Survey for 121.5 days from 1990 July 30 to 1991 January 25. In the course of the survey, optical photometry with various filters was peformed at several epochs, together with UV (IUE) and optical spectrophotometry. The spectral energy distribution in the 3 x 10(exp 14) -3 x 10(exp 17) Hz range is obtained simultaneously among the various frequencies to less than or = 1 day. No clear case of variability can be made in the X-rays, while in the optical and UV variability of 10%-20% is apparent. An analysis of IUE and Einstein archives indicates a doubling timescale of years for the UV and soft X-ray flux. The X-ray photon index, which in 1979 was rather flat (Gamma = 0.8(+0.6 -0.4), in 1990/1991 was found to be Gamma = 2.22 +/- 0.13, a typical value for radio-quiet quasars in this energy range. The overall energy distribution and the variability are discussed.
8 citations
TL;DR: In this paper, simultaneous photometric and spectrometric observations of the source E1013-477 in X-ray, UV, optical, and IR bands are presented in support of the recently proposed orbital period of 10.12 hr.
Abstract: Simultaneous photometric and spectrometric observations of the source E1013-477 in X-ray, UV, optical, and IR bands are presented. Evidence is found in support of the recently proposed orbital period of 10.12 hr. The X-ray spectra (0.1-10 keV) are well fitted by a single power law of photon index -0.8 with interstellar absorption N H ≤ 10 21 cm -2 . Discussing the classification of the source in the frame of the magnetic cataclysmic variables, it is concluded that E1013-477 is probably a new intermediate polar candidate
2 citations