<?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%">Mastichiadis, A.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">The implications of ultra-high-energy activity in X-ray binary systems</style></title><short-title><style face="normal" font="default" size="100%">Astronomy and Astrophysics</style></short-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Astrophysics</style></keyword><keyword><style  face="normal" font="default" size="100%">Electron-Positron Pairs</style></keyword><keyword><style  face="normal" font="default" size="100%">Energetic Particles</style></keyword><keyword><style  face="normal" font="default" size="100%">Gamma Ray Spectra</style></keyword><keyword><style  face="normal" font="default" size="100%">High Energy Interactions</style></keyword><keyword><style  face="normal" font="default" size="100%">Neutron stars</style></keyword><keyword><style  face="normal" font="default" size="100%">Pair Production</style></keyword><keyword><style  face="normal" font="default" size="100%">Pions</style></keyword><keyword><style  face="normal" font="default" size="100%">Stellar Luminosity</style></keyword><keyword><style  face="normal" font="default" size="100%">Stellar Spectra</style></keyword><keyword><style  face="normal" font="default" size="100%">X Ray Binaries</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1986</style></year><pub-dates><date><style  face="normal" font="default" size="100%">1986/11/1</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://ui.adsabs.harvard.edu/abs/1986A&amp;A...169..373M</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">169</style></volume><pages><style face="normal" font="default" size="100%">373 - 379</style></pages><isbn><style face="normal" font="default" size="100%">0004-6361</style></isbn><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">A mechanism for producing the high energy γ-ray spectrum of X-ray binaries exhibiting ultra-high-energy activity is proposed. γ-rays can result from decay of π&lt;SUP&gt;0&lt;/SUP&gt; produced in collisions of energetic protons with the keV ambient photons. Consequently, the X-ray photons modify the produced primary spectrum by selectively absorbing the lower energy part of it. As a result of this differential absorption these systems should exhibit a power law spectrum of index 1.5 - 2.0. Moreover, these systems should have a high electron-positron pair number density that will lead to 511 keV annihilation line emission.</style></abstract></record></records></xml>