Low frequency radio observations of SN 2011dh and the evolution of its   post-shock plasma properties
  We present late time, low frequency observations of SN 2011dh made using the Giant Metrewave Radio Telescope (GMRT). Our observations at $325\ \rm MHz$, $610\ \rm MHz$ and $1280\ \rm MHz$ conducted between $93-421\ \rm days$ after the explosion supplement the millimeter and centimeter wave observations conducted between $4-15 \ \rm days$ after explosion using the Combined Array for Research in Millimeter-wave Astronomy (CARMA) and extensive radio observations ($ 1.0-36.5\ \rm GHz$) conducted between $16-93\ \rm days$ after explosion using Jansky Very Large Array (JVLA). We fit a synchrotron self absorption model (SSA) to the $610\ \rm MHz$ and $1280\ \rm MHz$ radio light curves. We use it to determine the radius ($R_{\rm p}$) and magnetic field ($B_{\rm p}$) at $173$ \& $323$ days after the explosion. A comparison of the peak radio luminosity $L_{\rm op}$, with the product of the peak frequency $\nu_{\rm p}$ and time to peak $t_{\rm p}$ shows that the supernova evolves between the epochs of CARMA, JVLA and GMRT observations. It shows a general slowing down of the expansion speed of the radio emitting region on a timescale of several hundred days during which the shock is propagating through a circumstellar medium set up by a wind with a constant mass loss parameter, $\dot M/v_{\rm w}$. We derive the mass loss parameter ($A_{\star}$) based on $610\ \rm MHz$ and $1280\ \rm MHz$ radio light curves, which are found to be consistent with each other within error limits. 
Naveen Yadav (1,2), Alak Ray (1,3) and Sayan Chakraborti (3,4) ((1)   Tata Institute of Fundamental Research, Homi Bhabha Ro...
astro-ph.HE