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Title: Electron cooling in a young radio supernova: SN 2012aw

We present the radio observations and modeling of an optically bright Type II-P supernova (SN), SN 2012aw which exploded in the nearby galaxy Messier 95 (M95) at a distance of 10 Mpc. The spectral index values calculated using C, X, and K bands are smaller than the expected values for the optically thin regime. During this time, the optical bolometric light curve stays in the plateau phase. We interpret the low spectral-index values to be a result of electron cooling. On the basis of comparison between the Compton cooling timescale and the synchrotron cooling timescale, we find that the inverse Compton cooling process dominates over the synchrotron cooling process. We therefore model the radio emission as synchrotron emission from a relativistic electron population with a high energy cutoff. The cutoff is determined by comparing the electron cooling timescale, t {sub cool}, and the acceleration timescale, t-tilde {sub acc}. We constrain the mass-loss rate in the wind ( M-dot ∼1.9×10{sup −6} M{sub ⊙} yr{sup −1}) and the equipartition factor between relativistic electrons and the magnetic field ( α-tilde =ϵ{sub e}/ϵ{sub B}∼1.12×10{sup 2}) through our modeling of radio emission. Although the time of explosion is fairly well constrained by optical observations withinmore » about two days, we explore the effect of varying the time of explosion to best fit the radio light curves. The best fit is obtained for the explosion date as 2012 March 15.3 UT.« less
Authors:
;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ; ;  [6] ;  [7] ;  [8] ;  [9]
  1. Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)
  2. Institute for Theory and Computation, Harvard Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  3. Marquette University, Milwaukee, WI 53233 (United States)
  4. National Center for Radio Astronomy-TIFR, Pune 411007 (India)
  5. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  6. Aryabhhata Research Institute of Observational Sciences, Nainital 263129 (India)
  7. Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States)
  8. Indian Institute of Astrophysics, Bangalore 560034 (India)
  9. Department of Physics, Sam Houston State University, Huntsville, TX 77341 (United States)
Publication Date:
OSTI Identifier:
22348044
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 782; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BOLOMETERS; COMPARATIVE EVALUATIONS; ELECTRON COOLING; EMISSION; EXPLOSIONS; GALAXIES; MAGNETIC FIELDS; MASS TRANSFER; RELATIVISTIC RANGE; SIMULATION; STELLAR WINDS; SUPERNOVAE; VISIBLE RADIATION; X RADIATION