Abstract Details
| Name: C S Stalin Affiliation: Indian Institute of Astrophysics Conference ID: ASI2017_784 Title : Narrow Line Seyfert 1 galaxies Authors and Co-Authors : C. S. Stalin Suvendu Rakshit Indian Institute of Astrophysics Abstract Type : Oral Abstract Category : Extragalactic astronomy Abstract : Narrow Line Seyfert 1 (NLSy1) galaxies were identified as a new class of active galactic nuclei (AGN) by Osterbrock and his collaborators in the year 1985. Since then the number of NLSy1 galaxies has gradually increased and the last homogeneous catalog of NLSy1 galaxies was from SDSS-DR3 that resulted in 2011 NLSy1 galaxies. The interest in the study of NLSy1 galaxies has increased recently due to the detection of gamma ray emission in about half a dozen sources by the Fermi gamma-ray space telescope. This detection of gamma-rays in some NLSy1 galaxies indicate that they do have relativistic jets similar to blazars. Recent multi-band SED modeling results indicate that they resemble flat spectrum radio quasars. To augment the number of NLSy1 galaxies known as of today we have carried out a systematic analysis of sources classified as QSOs in SDSS-DR12. Our systematic study has yielded a new sample of about 11,000 sources, a factor of five increase from what is known today. Cross-correlating these new NLSy1 galaxies with the FIRST radio survey we found that only about 5% of NLSy1 galaxies are radio-loud. This is much lower than the 15% of radio-loud sources we know in quasars. Long-term optical variability study of this new sample of NLSy1 galaxies, using data that spans over 10 years, indicates that they show less variation compared to their broad line counterparts. Further details of this work will be discussed. |