Abstract Details
| Name: Dr. P. Seema Affiliation: University of Hyderabad Conference ID: ASI2018_1009 Title : Investigation of SPITZER MIR spectra on a sample of Ultra Large/ Large infra- red Galaxies to understand the role of Polycyclic Aromatic Hydrocarbons Authors and Co-Authors : P. Seema(1) , B.G.Anandarao(2), V. Venkataraman(2), P.K. Suresh (1), Teja Teppala (1) 1. University of Hyderabad, Hyderabad 2. Physical Research Laboratory, Ahmedabad Abstract Type : Poster Abstract Category : Stars,ISM and the Galaxy Abstract : With the availability of far infra-red data from Infrared Astronomical Satellite (IRAS,1983), it was discovered that there exists a large number of galaxies having luminosities > 10(+12) LϾ . These galaxies are known as Ultra Luminous Infra-Red Galaxies (ULIRGs). They play an important role in the formation of massive galaxies and Quasars. Their high luminosities were attributed either to starburst activity or to presence of AGNs (Active Galactic Nuclei) activity in these galaxies. The high sensitivity observations of Infra-red Space Observatory (ISO) and SPIZER brought a revolution in the understanding of the ULIRGs. It was found from these observations that the spectra of ULIRGs galaxies contain prominent 'PAH features' (Polycyclic Aromatic Hydrocarbon molecules), while these features were very weak or absent in AGNs. Therefore, these emission features can be used as a diagnostic tool in discriminating Starburst and AGN activity in ULIRGs. Even though there were numerous studies done in the past there was no clear picture about the prominent source of luminosity within these ULIRGs. Therefore more studies were required on a larger sample of galaxies, especially on the role of PAH molecules in contributing to the infrared flux in ULIRGs and have a better understanding of the evolution of these galaxies Our study involves a large sample of ULIRGs galaxies taken from the existing sample catalogues. Data analysis is performed using high resolution SPITZER spectra in mid-IR (3-15µm) region. Fluxes of the prominent PAH molecular features, 6.2µm, 7.7µm, 11.3µm which represent different modes of excitation, are extracted in most of the ULIRGs and their relative strengths are estimated. Preliminary results will be presented. |