The effect of dust scattering on the timing properties of black holes

Official URL: http://pos.sissa.it//archive/conferences/033/080/MQW6_080.pdf

It has been known that sources with high absorption column density also have high dust column density along the line of sight. The differential delays caused by small angle scattering of X rays by dust may have important effects on the power spectra of Galactic black holes at low energies, and impact studies that use the relation between the rms amplitude of variability and energy to determine the origin of QPOs from these sources. We observed the high absorption column density (NH ˜1023 cm-2 ) GBH 1E1740.7-2942 for 20 ks simultaneously with XMM-Newton and RXTE. By comparing the power spectra from the events in the core of the point spread function (PSF) of XMM-Newton EPIC-PN (using imaging and excluding the scattering halo) and the RXTE data, we quantified the effects of small angle scattering on the timing properties of this source. The rms amplitude of variability in ˜2-6 keV band obtained from the XMM-Newton data is higher than that of the RXTE as expected from the a scattering halo contribution in the RXTE.