Wednesday, July 10, 2013

1307.2366 (A. Corsi et al.)

A multi-wavelength investigation of a radio-loud supernova interacting with Helium-dominated circumstellar material    [PDF]

A. Corsi, E. O. Ofek, A. Gal-Yam, D. A. Frail, S. R. Kulkarni, D. B. Fox, M. M. Kasliwal, M. Sullivan, A. Horesh, J. Carpenter, K. Maguire, I. Arcavi, S. B. Cenko, Y. Cao, K. Mooley, Y. -C. Pan, B. Sesar, A. Sternberg, D. Xu, D. Bersier, P. James, J. S. Bloom, P. E. Nugent
We present the discovery, classification, and extensive panchromatic follow-up observations of PTF11qcj, a type Ibn supernova discovered by the Palomar Transient Factory. Our observations with the Karl G. Jansky Very Large Array show that this event is the first radio-loud member of the rare Ibn class: PTF11qcj reached a radio peak luminosity comparable to that of the famous gamma-ray-burst-associated supernova 1998bw (L5GHz ~ 10^{29} erg/s/Hz). PTF11qcj is also detected in X-rays with the Chandra observatory, and in the infrared band with Spitzer. Our multi-wavelength analysis probes the supernova interaction with a Helium-rich circumstellar material. The radio observations suggest a progenitor mass-loss rate of ~ 10^{-4} Msun/yr x (v_w/1000 km/s), and a velocity of ~(0.3-0.5)c for the fastest moving ejecta (at about 10d after explosion). However, these estimates are derived assuming the simplest model of supernova ejecta interacting with a smooth circumstellar material, and could be improved via modeling accounting for inhomogeneities in the medium and asphericity of the explosion. The X-ray flux from PTF11qcj is compatible with the high-frequency extrapolation of the radio synchrotron emission (within the large uncertainties). A light echo from pre-existing dust is in agreement with our data. Our analysis of pre-explosion images from the Palomar Transient Factory suggests that a precursor eruption of M_r ~ -13 mag may have occurred ~2.5 yr prior to the supernova explosion. We conclude that PTF11qcj fits the expectations from the explosion of a Wolf-Rayet star of the WNE class. Precursor eruptions may be a common feature during the final evolution of such stars.
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