Understanding the X-ray absorption and emission in archetypal radio-loud AGN 3C 273 with XMM Newton RGS

Abstract

In this thesis I present the results from high-resolution X-ray spectroscopic observations in the direction of Seyfert Type-1 AGN 3C 273, using RGS detectors mounted on XMM-Newton. AGNs are currently one of the most investigated objects in the universe. With the recent progress done in X-ray observations, mostly thanks to high resolution Chandra and XMM-Newton observatories, many questions could now be answered or addressed from a different perspective. Nonetheless, there is still a large number of questions to which this thesis, and many other papers will try to find an answer to. Using the observations, the recorded spectrum from 6 to 38 Ang was analysed with several models for fitting the continuum and distinct absorption and emission lines, provided by SPEX software package. We show that power-law (Γ = 1.54±0.01) describes the basic continuum model sufficiently,and is further improved by using ’warm’ Comptonisation (T ≈ 1.8 keV) to model the soft X-ray excess. We identify several gas absorption lines occurring in three different components of Milky Way gas, at temperatures approximately 0.5 eV, 10 ev, and 130 eV, with varying velocities between -100 km/s and 500 km/s, which is in agreement with the results obtained in previous studies of the source. We also identify broad emission lines of O VII and Ne IX triplet, as well as O VIII Lyman-α emissions in broad line region (BLR) of the AGN. We investigate the possibility of photoionised plasma absorption lines from the AGN wind, but can only determine an upper limit of the NH. This limit is relatively low, NH = 1.9^(+2)_(−1) × 10^(22) m^(−2), and therefore does not substantially improve the fit to the spectrum, which suggest that there is no significant wind present in this radio-loud AGN.