<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Konopelko, A.</style></author><author><style face="normal" font="default" size="100%">Mastichiadis, A.</style></author><author><style face="normal" font="default" size="100%">Kirk, J.</style></author><author><style face="normal" font="default" size="100%">de Jager, O. C.</style></author><author><style face="normal" font="default" size="100%">Stecker, F. W.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Modeling the TeV Gamma-Ray Spectra of Two Low-Redshift Active Galactic Nuclei: Markarian 501 and Markarian 421</style></title><short-title><style face="normal" font="default" size="100%">The Astrophysical Journal</style></short-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Astrophysics</style></keyword><keyword><style  face="normal" font="default" size="100%">galaxies: active</style></keyword><keyword><style  face="normal" font="default" size="100%">Galaxies: BL Lacertae Objects: Individual: Name: Markarian 421</style></keyword><keyword><style  face="normal" font="default" size="100%">Galaxies: BL Lacertae Objects: Individual: Name: Markarian 501</style></keyword><keyword><style  face="normal" font="default" size="100%">Gamma Rays: Observations</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2003</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2003/11/1</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://ui.adsabs.harvard.edu/abs/2003ApJ...597..851K</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">597</style></volume><pages><style face="normal" font="default" size="100%">851 - 859</style></pages><isbn><style face="normal" font="default" size="100%">0004-637X</style></isbn><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">We discuss the results of modeling the TeV γ-ray spectra of two active galactic nuclei, Mrk 501 and Mrk 421, that have almost the same redshifts: z=0.031 and 0.034, respectively. The effect of intergalactic γ-ray absorption is treated as an uncertainty in the measurement of the intrinsic spectrum. Although the objects differ, we obtain satisfactory fits for both of them in a synchrotron self-Compton scenario. Compared to previous models, our fits are characterized by higher values of the Doppler factor (δ&amp;gt;=50) and an electron injection spectrum extending to higher energies (γ&lt;SUB&gt;max&lt;/SUB&gt;&amp;gt;=1.5×10&lt;SUP&gt;5&lt;/SUP&gt;). In the case of Mrk 421, the observed difference in spectral slope in X-rays and TeV γ-rays between the high and low states can be explained as a variation of a single parameter-the maximum energy γ&lt;SUB&gt;max&lt;/SUB&gt;mc&lt;SUP&gt;2&lt;/SUP&gt; at which electrons are injected.</style></abstract></record></records></xml>