### Multi-Wavelength Study of Narrow-Line Seyfert 1 Galaxies

Speaker : Vineet Ojha
Affiliation : ARIES
Date & Time :
Venue : Auditorium
Abstract :

Narrow-line Seyfert 1 galaxies (NLSy1s) are a peculiar class of lower luminosity AGNs, characterised by the narrow width of optical Balmer emission lines FWHM(H${\beta}$)$<$ 2000 km s$^{-1}$, a small flux ratio [O$_{III}]_{\lambda5007}/H\beta<$ 3 and strong permitted optical/UV Fe~{\sc ii} emission lines. As a class of lower luminous AGN, NLSy1s were initially classified as radio-quiet objects, which were thought not to eject relativistic jets like those observed in radio-loud AGNs. However, unexpected discovery of $\gamma$-ray emissions from more than a dozen of NLSy1s since the launch of {\it Fermi}-Gamma-ray telescope and realisation that essentially all of them have detection ($>$ 3$\sigma$) in radio band too, has brought real path break in the field of NLSy1s which harbour lower black hole masses. In these contexts, I will briefly discuss my Ph. D. work which is dedicated to understanding the enigmatic problem of getting high energy $\gamma$-ray emissions from NLSy1s, hosted by spiral galaxies and primarily classified as radio-quiet AGNs. In addition to this, I will also briefly discuss a detailed X-ray spectral analysis in conjunction with optical data for a large sample of 221 NLSy1s as compare to its luminosity-redshift (L-z) matched control sample of 154 Broad-line Seyfert 1 galaxies (BLSy1s) which has been done as a dedicated work in my Ph.D. to understand the X-ray emission mechanism of NLSy1s and its comparison with other luminous classes of AGN. At the end of each project, I will discuss a proposed future work which I will do during my PDF tenure at ARIES using ARIES 1.04-m ST, 1.30-m DFOT facilities and archival data.