• Fulltext

       

        Click here to view fulltext PDF


      Permanent link:
      https://www.ias.ac.in/article/fulltext/joaa/008/01/0033-0050

    • Keywords

       

      radio sources, extragala ctic; angular-size-flux-density relation; cosmology; radio sources, evolution

    • Abstract

       

      The interpretation of the observed relation between median angular sizes (θm) of extragalactic radio sources and flux density at 408 MHz has been examined. The predictedθm-S relations based on well-observed strong sources in parent samples selected at 178 and 1400 MHz, and existing models of the evolving radio luminosity function can be made to fit the observed relation only by invoking cosmological evolution in linear sizes even for theq0 = 0 universe. Predictions based on a parent sample at 2.7 GHz are shown to overestimate the contribution of steep-spectrum, compact (SSC) sources in low-frequency samples unless the downward curvature in the spectra of such sources is taken into account. When approximate corrections are made for this effect, predictions based on the 2.7 GHz parent sample cannot obviate the need for linear size evolution as claimed in the literature.

    • Author Affiliations

       

      V. K. Kapahi1 V. K. Kulkarni2 C. R. Subrahmanya1

      1. Tata Institute of Fundamental Research, Post Box No. 1234, Bangalore - 560012
      2. Radio Astronomy Centre, Tata Institute of Fundamental Research, Post Box No. 8, Ootacamund - 643001
    • Dates

       
  • Journal of Astrophysics and Astronomy | News

    • Continuous Article Publication

      Posted on January 27, 2016

      Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately. All these have helped shorten the publication time and have improved the visibility of the articles.

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2017-2019 Indian Academy of Sciences, Bengaluru.