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      https://www.ias.ac.in/article/fulltext/joaa/028/01/0029-0040

    • Keywords

       

      Blazars: general; galaxies: active, quasars, jets, nuclei, radio continuum.

    • Abstract

       

      We present diagrams depicting the expected inter-dependences of two key kinematical parameters of radio knots in the parsec-scale jets of blazars, deduced from VLBI observations. The two parameters are the apparent speed (𝑣app = c𝛽app) and the effective Doppler boosting factor (𝛿eff) of the relativistically moving radio knot. A novel aspect of these analytical computations of 𝛽–𝛿 diagrams is that they are made for parsecscale jets having a conical shape, with modest opening angles (𝜔 up to 10°), in accord with the VLBI observations of the nuclei of the nearest radio galaxies. Another motivating factor is the recent finding that consideration of a conical geometry can have important implications for the interpretation of a variety of radio observations of blazar jets. In addition to uniform jet flows (i.e., those having a uniform bulk Lorentz factor, 𝛤), computational results are also presented for stratified jets where an ultra-relativistic central spine along the jet axis is surrounded by a slower moving sheath, possibly arising from a velocity shear.

    • Author Affiliations

       

      Gopal-Krishna1 Pronoy Sircar2 Samir Dhurde3

      1. National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Pune University Campus, Post Bag No. 3, Pune 411 007, India.
      2. Department of Physics, Indian Institute of Technology, Kanpur, India.
      3. Inter-University Centre for Astronomy & Astrophysics, Pune University Campus, Post Bag No. 4, Pune 411 007, India.
    • Dates

       
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