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Paper: Time Lag in the X-ray Dust Scattering Halo of Cyg X-1
Volume: 404, The Eighth Pacific Rim Conference on Stellar Astrophysics: A Tribute to Kam Ching Leung
Page: 144
Authors: Zhang, S.N.; Ling, Z.; Xiang, J.; Tang S.
Abstract: X-ray photons scattered by the interstellar, carry the information of dust distribution, dust grain model, scattering cross section, and the distance of the source and so on; they also take longer time than the unscattered photons. Using a cross-correlation method, we study the light curves of the X-ray dust scattering halo of Cyg X-1, observed with the Chandra X-ray Observertary. Significant time lags are found between the light curves of the point source and its halo. This time lag increases with the angular distance from Cyg X-1, implying a dust concentration in the location of 2.0 kpc × (0.876 ± 0.002). By fitting the observed light curves of the halo at different radii with simulated light curves, we obtain a width of ΔL = 33+18-13 pc of this dust concentration. The origin of this dust concentration is still not clearly known.
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