| Name: AYON MONDAL |
| Affiliation: PRESIDENCY UNIVERSITY, KOLKATA |
| Conference ID: ASI2026_33 |
| Title: A Two-Decade X-ray and UV Spectral-Timing Study of Mrk 766: Disk Reflection, Outflows, and the Evolution of Fe~K$\alpha$ Complex |
| Abstract Type: Poster |
| Abstract Category: High Energy Phenomena, Fundamental Physics and Astronomy |
| Author(s) and Co-Author(s) with Affiliation: Ayon Mondal(Presidency University, 86/1 College Street, Kolkata - 700073, India), Tathagata Saha(Inter-University Centre for Astronomy and Astrophysics (IUCAA), Pune, Maharashtra - 411007, India), Arijit Sar(Presidency University, 86/1 College Street, Kolkata - 700073, India), Ritaban Chatterjee(Presidency University, 86/1 College Street, Kolkata - 700073, India) |
| Abstract: We present a multi-epoch, primarily X-ray study of the narrow-line Seyfert 1 (NLSy1) galaxy Mrk~766 by combining archival \textit{XMM-Newton} observations spanning nearly two decades together with a \textit{XRISM} observation obtained during its Performance Verification Phase. We analyzed the absorption and emission features in the soft X-ray spectra from RGS and EPIC-pn data, revealing a stratified multi-phase potentially ionised absorber with a varying column density at a timescale of $\sim$1 day. The covering fraction of the absorber shows a systematic increase by a factor of 1.1 while the continuum flux increases by a factor of 3.4, supporting radiation-driven outflows. Mrk~766 exhibits a multi-component Fe K$\alpha$ emission line as revealed by fits to the \textit{XRISM} data. A quasi-phenomenological model comprising a torus and a broad \textit{diskline} component distinguishes the two components and constrains the inner radius of the potential broad line emitting disk substructure between $R_{in}=40–60~r_{\rm g}$. Analysis of multiple epochs of the Fe K$\alpha$ complex across \textit{XMM-Newton} observations reveals that the broad component tracks the continuum flux closely and effectively reflects the trend with respect to the continuum. The narrow component is consistent with a distant emitter, potentially the torus. Quasi-simultaneous monitoring with \textit{Swift}-XRT and UVOT further indicates UV emission lagging the X-rays by $5.9^{+4.1}_{-5.7}$ hours, consistent with disk reprocessing of coronal X-ray fluctuations, and corresponds to a light travel distance of up to $10^{3}~r_{\rm g}$. Overall, our analysis maps the extent of the dynamically evolving absorber, the iron line emitter, and the accretion disk in this highly accreting NLSy1 system. |
