A long-term study of Mrk 50 : Appearance and disappearance of soft excess

TL;DR

This long-term study of Mrk 50 reveals the transient nature of its soft X-ray excess and confirms the absence of obscuration, providing insights into the variability and accretion processes of this Seyfert 1 AGN over 15 years.

Contribution

First comprehensive 15-year multiwavelength analysis of Mrk 50, demonstrating the appearance and disappearance of soft excess and characterizing its spectral and temporal behavior.

Findings

Soft excess was present between 2007-2010 and vanished afterward.

Mrk 50 shows no signs of obscuration, indicating a 'bare' nucleus.

The AGN accretes at sub-Eddington rates throughout the observation period.

Abstract

We present an extensive temporal and spectral study of the Seyfert 1 AGN Mrk 50 using 15 years (2007-2022) of multiwavelength observations from XMM-Newton, Swift, and NuSTAR for the first time. From the timing analysis, we found that the source exhibited variability of $\sim$20 % during the 2007 observation, which reduced to below 10 % in the subsequent observations and became non-variable in the observations from 2010 onward. From the spectral study, we found that the spectra are nearly featureless. Non-detection of absorption in the low-energy domain during the 15 years of observation infers the absence of obscuration around the central engine, rendering the nucleus a `bare' type. A prominent soft X-ray excess below 2 keV was detected in the source spectrum during the observations between 2007 and 2010, which vanished during the later observations. To describe the nature of the soft excess, we use two physical models, such as warm Comptonization and blurred reflection from the ionized accretion disk. Both the physical models explain the nature and origin of the soft excess in this source. Our analysis found that Mrk~50 accretes at sub-Eddington accretion rate ($\lambda_{Edd}=0.13-0.02$) during all the observations used in this work.