Fürst, F.Kreykenbohm, I.Pottschmidt, KatjaWilms, J.Hanke, M.Rothschild, R. E.Kretschmar, P.Schulz, N. S.Huenemoerder, D. P.Klochkov, D.Staubert, R.2023-09-262023-09-262010-09-09Fürst, F., I. Kreykenbohm, K. Pottschmidt, J. Wilms, M. Hanke, R. E. Rothschild, P. Kretschmar, et al. “X-Ray Variation Statistics and Wind Clumping in Vela X-1.” Astronomy & Astrophysics 519 (September 1, 2010): A37. https://doi.org/10.1051/0004-6361/200913981.https://doi.org/10.1051/0004-6361/200913981http://hdl.handle.net/11603/29887We investigate the structure of the wind in the neutron star X-ray binary system Vela X-1 by analyzing its flaring behavior. Vela X-1 shows constant flaring, with some flares reaching fluxes of more than 3.0 Crab between 20-60 keV for several 100 s, while the average flux is around 250 mCrab. We analyzed all archival INTEGRAL data, calculating the brightness distribution in the 20-60 keV band, which, as we show, closely follows a log-normal distribution. Orbital resolved analysis shows that the structure is strongly variable, explainable by shocks and a fluctuating accretion wake. Analysis of RXTE ASM data suggests a strong orbital change of NH. Accreted clump masses derived from the INTEGRAL data are on the order of 5 x 10¹⁹ - 10²¹ g. We show that the lightcurve can be described with a model of multiplicative random numbers. In the course of the simulation we calculate the power spectral density of the system in the 20-100 keV energy band and show that it follows a red-noise power law. We suggest that a mixture of a clumpy wind, shocks, and turbulence can explain the measured mass distribution. As the recently discovered class of supergiant fast X-ray transients (SFXT) seems to show the same parameters for the wind, the link between persistent HMXB like Vela X-1 and SFXT is further strengthened.8 pagesen-USThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.Attribution 4.0 International (CC BY 4.0)https://creativecommons.org/licenses/by/4.0/Text