Toz saçılım harelerinin galaktik transit karadeliklerin zamansal ozelliklerine etkileri

Sources with high column density of absorption have also been known to have high column density of dust along the line of sight. The process of small angle scattering of X-rays by the dust grains in the molecular clouds can produce delays on the order of days. Moreover, the scattering cross-section scales as ~E^{-2} where E is the energy of the X-ray photon, which means the low energy photons are heavily scattered. The differential delays caused by the scattering process may cause loss of coherence and a decrease in the rms amplitude of variability, therefore may impact the studies that use the correlations between the rms amplitude of variability and energy. We observed the Galactic black hole 1E1740.7-2942 which has very high column density (N_H ~10^{23}) for ~20 ks with XMM-Newton and RXTE simultaneously. We also used an archival Chandra observation to diagnose if the dust scattering halo (DSH) is present. We characterized the DSH emission in 2.11-5.86 keV energy band by spectral means and also by comparing the power spectra from XMM-Newton and RXTE. We also investigated the possible location of the HCO^+ cloud relative to the source. Finally, we propose a correction method to obtain the ``intrinsic'' power spectra and rms amplitude of variability values for XMM-Newton and RXTE observations that are behind ample amount of interstellar medium.