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      Permanent link:
      https://www.ias.ac.in/article/fulltext/joaa/039/05/0061

    • Keywords

       

      QSOs; photometric classification; point-sources; SDSS-GALEX; SED fitting; UV-optical photometry.

    • Abstract

       

      We have classified a sample of 37,492 objects from SDSS into QSOs, galaxies and stars using photometric data over five wave bands ($u, g, r , i$ and $z$) and UV GALEX data over two wave bands (near-UV and far-UV) based on a template fitting method. The advantage of this method of classification is that it does not require any spectroscopic data and hence the objects for which spectroscopic data is not available can also be studied using this technique. In this study, we have found that our method is consistent by spectroscopic methods given that their UV information is available. Our study shows that the UV colours are especially important for separating quasars and stars, as well as spiral and starburst galaxies. Thus it is evident that the UVbands play a crucial role in the classification and characterization of astronomical objects that emit over a wide range of wavelengths, but especially for those that are bright at UV. We have achieved the efficiency of 89% for the QSOs, 63% for the galaxies and 84% for the stars. This classification is also found to be in agreement with the emission line diagnostic diagrams.

    • Author Affiliations

       

      AYESHA ANJUM1 MOUSUMI DAS2 JAYANT MURTHY2 S. B. GUDENNAVAR1 RAJESH GOPAL3 S. G. BUBBLY1

      1. Department of Physics and Electronics, CHRIST (Deemed to be University), Bengaluru 560 029, India.
      2. Indian Institute of Astrophysics, II Block, Kormamangala, Bengaluru 560 034, India.
      3. Department of Physics, CMR Institute of Technology, Bengaluru 560 037, India.
    • Dates

       
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