Abstract Details
| Name: Subhashree Swain Affiliation: Ph.D. scholar,Pondicherry University Conference ID: ASI2018_1575 Title : A brief study of the nature of Active Galaxies(AG) through Seyfert Unification Scheme in UV and IR band(8µm) Authors and Co-Authors : K.V.P Latha, Pondicherry University, Puducherry P. Shalima, Regional Institute of Education, Mysore Prajval Shastri, Indian Institute of Astrophysics,Bengaluru Abstract Type : Poster Abstract Category : Extragalactic astronomy Abstract : GALEX is a NASA small orbiting telescope, which observes in Ultra-Violet light across 10 billion years of cosmic history. It is conducting several sky surveys, including extra galactic UV sky surveys. It has two bands i.e one is NUV(Near UV) in between 1750-2800Å angst. and other is FUV(Far UV) in between 1350-1750Å with 6-8 arc second resolution. The field of view is 1.27 degree and 1.25 degree for FUV band and NUV bands respectively. For this work, we have usedThe GALEX data extracted from the Nearby Galaxies Survey(NGS) and All Image Sky survey(AIS). Infra-red data is taken from Spitzer Archive of IRAC 8micron-meter band. We have studied 8 Active galaxies of Seyfert 1 type and 8 Active galaxies of Seyfert type 2. As data in two UV bands are available, i.e. NUV and FUV, we have compared the fluxes in these bands with the data in the Mid-IR band for our sample of Seyfert galaxies. From the results, it is noticed that IR flux is greater than the UV flux for both types of galaxies. In addition, the ratio of Mid-IR and NUV luminosities is nearly the same in most of the galaxies. We also find that there is no significant difference in the Mid-IR luminosity between the type 1 and type 2 galaxies. However, we expect that, Seyfert 1s should be brighter in the IR than Seyfert 2s because the torus is a thick structure surrounding the central AGN with its inner edge hotter than the outer edge. The IR radiation emitted by the inner edge is obscured by the torus in Seyfert 2 galaxies. In Seyfert 2s we only observe radiation from the outer edge which is colder than the inner edge of the torus. However in 1s type, we get radiation from the inner edge as well. So therefore in Seyfert 1s, IR should be higher than Seyfert 2s according to the model made by E.A. Pier and J.H. Krolik. Where as in Seyfert type 2 galaxy, we do not see directly into the center of the AGN. We get to see the edge on view where the UV radiation is absorbed by the torus. So we expect lower UV luminosities in this case. However, here we find that both the types of galaxies have similar IR and UV luminosities. This result could contribute to a better understanding of the AGN Unification Scheme. We will be investigating these results more thoroughly with a larger sample in the coming days. |