Abstract Details
| Name: Nagendra Kumar Affiliation: Ph.D. Student, IUCAA, Pune-411007, India Conference ID: ASI2015_842 Title : Rapid variability in NS LMXBs and the thermal Comptonization process. Authors and Co-Authors : Ranjeev Misra IUCAA, Pune-411007, India Abstract Type : Poster Abstract Category : Stars, The Milky Way Galaxy and its neighbours Abstract : In neutron star low-mass X-ray binaries (NS LMXBs) system the X-ray photons varied rapidly (of order of milliseconds), this variability has quasi periodic nature (termed as kHz QPO) and occurred frequently in lifetime. The X-ray spectrum is explained usually in terms of thermal Comptonization process and it is correlated with kHz QPOs. We have described a thermal Comptonization model for kHz QPOs in NS LMXB which also constrained the size of the Comptonizing medium with comparing the energy dependency of kHz QPO. We have explored the relation between medium size and kHz QPO frequencies for both type of LMXBs transient and persistent source, but this relation depends on adequate spectral modeling. In transient source, for one spectral model, the medium size is increased as kHz QPO frequencies are decreased but not such clear distinction for other spectral model. In addition, to explain the time lags (between two energy band) associated to kHz QPO frequencies, we have taken an additional assumption that significant fraction of Comptonized photons impinge back to the seed photon source. To check this assumption we have set up a Monte Carlo experiment for Compton scattering process and studied the relation between fraction of return back Comptonized photons and the geometry of the comptonizing system. |