An analysis of the synchrotron self-compton model for the multi-wave band spectra of blazars

被引:409
作者
Bloom, SD [1 ]
Marscher, AP [1 ]
机构
[1] TECHNION ISRAEL INST TECHNOL, ASHER SPACE RES INST, IL-32000 HAIFA, ISRAEL
关键词
BL Lacertae objects; general; quasars; radiation mechanisms; nonthermal;
D O I
10.1086/177092
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
The effects of varying key physical parameters of a source emitting synchrotron self-Compton (SSC) radiation are examined in relation to the broadband spectrum of blazars, with emphasis on the high-energy gamma-ray spectrum. We also explore the connection between observational parameters, such as angular size, and the predicted spectra. Model spectra show that the relationship of the predicted variations of high-energy flux densities to those at radio to infrared wavelengths is sensitive to whether magnetic field or relativistic electron density dominates the variations. Furthermore, models that involve the scattering of external seed photons can be discerned from SSC models based on the relative variability amplitudes of the high- and low-energy emission. Second-order self-Compton scattering tends to dominate the gamma-ray emission in sources with steeper spectral indices, provided that the other observed properties (flux, spectral turnover, etc.) are roughly equal. Also, if the emission at the highest energies is due to second-order scattering, and if the quantity nu F-nu at X-ray frequencies is less than that in the radio-IR domain, then the value of nu F-nu in the gamma-ray range must be less than that in the X-ray range. In general, the second-order spectra show strong curvature, contrary to observations, while the nu F-nu spectrum of first-order scattering has a broad, flat peak that could be mistaken for a power law of slope near zero. These considerations lead us to conclude that, in general, second-order SSC emission does not dominate the hard gamma-ray emission from gamma-ray-bright blazars. However, first-order SSC emission remains a prime candidate for explaining the hard gamma-rays observed in these sources.
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页码:657 / 663
页数:7
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