AAS 207th Meeting, 8-12 January 2006
Session 141 Blazars and AGN Variability
Poster, Wednesday, 9:20am-6:30pm, January 11, 2006, Exhibit Hall

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[141.09] X-ray Spectral Variability of TeV Blazars

Y. Q. Xue, F. Yuan, W. Cui (Purdue University)

TeV blazars radiate maximum (and comparable) amount of power at both keV and TeV energies. While the origin of the gamma-ray emission is still being debated, the X-ray emission is generally believed to originate in the synchrotron emission from relativistic electrons in the jet of these sources. We report results from a systematic modeling of X-ray spectral variability of Mrk 421 and Mrk 501 during major flares, making use of some of the high-quality data that have recently become available. The X-ray spectra of the two sources fall on the opposite sides of the synchrotron peak in their respective spectral energy distributions (SEDs). So they together may offer additional insights into the physical origin of X-ray spectral variability of TeV blazars. Assuming that the X-ray emission comes from the synchrotron radiation from a homogeneously distributed electron population of power-law spectral shape, we model the X-ray spectrum quantitatively by varying four key parameters: electron spectral index (p), magnetic field (B), maximum Lorentz factor (\gammamax), and electron energy density (Etot). While there is considerable degeneracy in the theoretical fits, we show that, in order to account for the X-ray spectral variability observed in Mrk 421, at least three of the four parameters are required to vary in most cases, with p being one of them. The observations of Mrk 501 support the conclusion, although the quality of the data is not as good as Mrk 421. We discuss the implications of the results.

This work was supported in part by NASA Grants NAG5-13736 and NNG04GP86G.

The author(s) of this abstract have provided an email address for comments about the abstract: xuey@physics.purdue.edu

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