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Name: HARIKRISHNA SRIPADA Affiliation: Dept. of Astronomy, Osmania University Conference ID: ASI2020_160 Title : Vertical oscillations of the radiation dominated inner accretion disk region and its implication on QPOs. Authors and Co-Authors : S.Harikrishna, K.Sriram Abstract Type : Poster Abstract Category : Stars, ISM and Galaxy Abstract : We attempt to explain the normal branch oscillations (NBOs) in Z sources and type-B Quasi Periodic Oscillations (QPOs) in black hole X-ray binaries (BHXBs) as oscillations in the inner region of the accretion disk, dominated by the radiation pressure, and those in the outer region that is Shakura-Sunyaev (SS) disk. We tested different surface density distributions in the accretion disk and found that the vertical oscillation of this configuration produces ∼ 6-25 Hz frequencies .The inner region of accretion disk was puffed-up to a certain radius and the oscillation frequencies were observed at >6 Hz that are often seen as NBOs and flaring branch oscillations (FBOs, 8-21 Hz) observed in Sco X-1 and GX 17+2. It was found that the oscillations should occur in a few hundreds to thousand Schwarzschild radius in the case of Z sources and BHXBs. These results are consistent with the frequencies observed in Z sources in the form of NBOs and FBOs. We found that the instability radii associated with the appearance of NBO in Z sources and type-B QPO in BHXBs were closely matching with oscillation radii in our model. |