Long term X-ray spectral variations of the Seyfert-1 galaxy Mrk 279

TL;DR

This study analyzes long-term X-ray spectral variations of the Seyfert-1 galaxy Mrk 279 using data from AstroSat, NuSTAR, and XMM-Newton between 2018 and 2020, revealing flux variability and spectral shape changes over time.

Contribution

It provides a comprehensive multi-mission analysis of Mrk 279's X-ray spectral variability, highlighting the long-term flux and spectral shape changes and their correlations.

Findings

Significant flux variations observed over the years.

Spectral shape, indicated by photon index, varies only over longer timescales.

No strong correlation between fluxes and photon indices found.

Abstract

We present the results from a long term X-ray analysis of Mrk 279 during the period 2018-2020. We use data from multiple missions - AstroSat, NuSTAR and XMM-Newton, for the purpose. The X-ray spectrum can be modelled as a double Comptonisation along with the presence of neutral Fe K${\alpha}$ line emission, at all epochs. We determined the source's X-ray flux and luminosity at these different epochs. We find significant variations in the source's flux state. We also investigated the variations in the source's spectral components during the observation period. We find that the photon index and hence the spectral shape follow the variations only over longer time periods. We probe the correlations between fluxes of different bands and their photon indices, and found no significant correlations between the parameters.