Abstract
Gamma-ray emission from the bright radio source 3C 84, associated with the Perseus cluster, is ascribed to the radio galaxy NGC 1275 residing at the centre of the cluster. Study of the correlated X-ray/gamma-ray emission from this active galaxy, and investigation of the possible disk-jet connection, are hampered because the X-ray emission, particularly in the soft X-ray band (2–10 keV), is overwhelmed by the cluster emission. Here we present a method to spectrally decouple the cluster and active galactic nucleus (AGN) emission in imaging X-ray detectors. We use three sets of simultaneous Niel Gehrels Swift XRT and NuStar data. These observations were made during the period 2015 November to 2017 February, when a huge increase in the gamma-ray emission was observed. We find that the gamma-ray emission shows a very high degree of variability (40%–50%) on time scales of 1–10 days, whereas the hard X-ray emission, associated with the AGN, shows a low variability (∼15%–30%), on various time scales in the range of 0.01–60 days.
Highlights
NGC 1275 is a radio galaxy located at the centre of the Perseus cluster
In this paper we report the results of our investigation of this source using the X-ray Telescope (XRT)-NuSTAR observations which were made in the period of 2015–2017, when a long term gamma-ray flare was observed
For circular region with radius of 1’, at energies above 19 keV, contribution to total flux from apec is less than 10%
Summary
NGC 1275 is a radio galaxy located at the centre of the Perseus cluster This galaxy harbours an active galactic nucleus (AGN), and it is classified as a Fanaroff–Riley I radio galaxy based on radio morphology. This is one of the closest AGNs at a redshift of 0.01756 [1]. The optical emission from the nucleus was found to be variable and strongly polarized from 3% to 6% [5,6,7] This implies a significant contribution from the putative relativistic jet to Galaxies 2020, 8, 63; doi:10.3390/galaxies8030063 www.mdpi.com/journal/galaxies
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
