Colloquium on 27 March 2015
Narrow line Seyfert 1 galaxies: a new class of gamma-ray emitting AGN

Details

Title: Narrow line Seyfert 1 galaxies: a new class of gamma-ray emitting AGN
Speaker: C.S. Stalin
Date: Friday, 27 March 2015
Time: 12:00 - 13:00
Venue: SAAO Auditorium

Abstract

The launch of the Fermi gamma-ray space telescope in the year 2008 has led to the discovery of gamma-ray emission from more than thousands of celestial sources based on the first two years of its operation. Considering only the extragalactic sky, blazars dominate the population of gamma-ray emitting sources. Prior to Fermi, only two classes of gamma-ray emitting AGN were known, namely radio galaxies and quasars. However, since the launch of Fermi, gamma-ray emission has also been detected in a total of five Narrow line Seyfert 1 (NLSy1) galaxies, which clearly demonstrates the existence of a third class of gamma-ray emitting AGN. The detection of gamma-rays from NLSy1 galaxies have established beyond doubt the presence of relativistic jets in these sources. However, it is generally thought that NLSy1 ga laxies are hosted by spiral galaxies, and if it is true, then spiral galaxies can also launch relativistic jets. We have carried out a systematic study of these newly discovered gamma-ray emitting NLSy1 galaxies, using data in the optical/IR from ground based telescopes, UV and X-rays from Swift/UVOT, Swift/XRT and Swift/BAT, and gamma-rays from Fermi. We have found that these new gamma-ray emitting NLSy1 galaxies have properties similar to the Flat Spectrum Radio Quasar (FSRQ) category of AGN. However, we find one of the gamma-ray emitting NLSy1 galaxies to have both the characteristics of a Seyfert galaxy and a FSRQ.

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