| Name: | Shree Suman |
| Affiliation: | Indian Institute of Technology,Hyderabad |
| Conference ID : | ASI2024_467 |
| Title : | X-ray Reverberation and Spectral Variability in Seyfert type 1 Galaxies: NGC 4593 |
| Authors : | Shree Suman ,Mayukh Pahari |
| Authors Affiliation: | Department of Physics, Indian Institute of Technology Hyderabad, Kandi-502284, Telangana,India |
| Mode of Presentation: | Oral |
| Abstract Category : | Galaxies and Cosmology |
| Abstract : | The near UV to optical reverberation mapping of strongly variable Seyfert galaxies are consistent with standard disk prescriptions, however, Far UV to X-ray variability departs. To understand the accretion geometry close to supermassive black holes, an X-ray reverberation study is the most powerful technique. In this study, we focus on the Seyfert 1 galaxy NGC 4593, known for its strong short-term flux variations, and conduct a comprehensive analysis of X-ray reverberation. • Utilizing long XMM-Newton observations from 2002 (∼78 ks) and 2016 (∼135 ks), we divide the data into high-flux (≥ 16 counts/sec) and low-flux regimes (≤ 14 counts/sec) and determine the accretion disc geometry by applying the lamppost configuration of disk and corona. Using a GR relativistic model we uncover a remarkable observation: the corona consistently resides close to the event horizon. This results in a significant gravitational light-bending effect that enhances the reflection fraction, with corona heights ranging from approximately 2.7 to 3.5 times the Schwarzschild radius. To uncover the underlying variable spectral component we develop Python codes to calculate photon energy-dependent RMS and covariance spectra. Our analysis reveals the presence of a stronger variability spectral component during the low flux observation while the variability is suppressed during the high flux. Using variability analysis we aim to accurately determine the inner disc-corona geometry across various mass accretion rates. Analyzing the X-ray time delay between 0.3-2 keV (reflection-dominated soft excess) and 2-5 keV (continuum-dominated hard X-ray) in NGC 4593, we observed that changing coronal height and disk ionisation from high to low flux are consistent with that obtained from relativistic reflection modelling. To explain our results, we plan to extend our work by exploring other models like extended corona and test their validity. |
