Abstract Details
| Name: Sheelu Abraham Affiliation: St. Thomas College, Kozhencheri, Kerala Conference ID: ASI2015_598 Title : Photometric Redshifts of Quasars from SDSS Authors and Co-Authors : Ninan Sajeeth Philip, St. Thomas College, Kozhencheri, Kerala Abstract Type : Poster Abstract Category : Extragalactic astronomy Abstract : With the availability of large volume of astronomical data with unconfirmed nature, the accurate photometric classification and redshift estimations are still remaining as major challenges in the observational astronomy. The best way to find the redshift of an astronomical source is to take its spectrum. However, there are situations where the spectroscopic estimation becomes impossible due to poor signal-to-noise ratio, instrumental systematics or that the brightness of the object under study is fainter than the spectroscopic limit. Moreover, given the large number of objects, it is necessary to have some prior knowledge that would help one to shortlist the interesting objects for spectroscopic observations. We therefore address the problem of photometric redshifts of unresolved point sources, especially quasars, using photometric colour information from Sloan Digital Sky Survey (SDSS). SDSS was chosen because it was primarily designed to track quasars. In the present study, we have used the DBNN Bayesian classifier for the estimation of the photometric redshifts of quasars using 10 colours and one magnitude from SDSS as the input features. There are ~158,165 known quasars which span the redshift range 0 to 7 in SDSS i - band magnitudes brighter than 23. We report the accuracy of the predictions within different error bars and identify the colour regions as a function of predictability confidence. The poster presentation shall cover the major findings of this work. |