The Double-peaked Radio Light Curve of Supernova PTF11qcj
We present continued radio and X-ray follow-up observations of PTF11qcj, a highly energetic broad-lined Type Ic supernova (SN), with a radio peak luminosity comparable to that of the γ-ray burst (GRB) associated SN 1998bw. The latest radio observations, carried out with the Karl G. Jansky Very Large Array, extend up to ~5 yr after the PTF11qcj optical discovery. The radio light curve shows a double-peak profile, possibly associated with density variations in the circumstellar medium (CSM), or with the presence of an off-axis GRB jet. Optical spectra of PTF11qcj taken during both peaks of the radio light curve do not show the broad Hα features typically expected from H-rich circumstellar interaction. Modeling of the second radio peak within the CSM-interaction scenario requires a flatter density profile and an enhanced progenitor mass-loss rate compared to those required to model the first peak. Our radio data alone cannot rule out the alternative scenario of an off-axis GRB powering the second radio peak, but the derived GRB parameters are somewhat unusual compared to typical values found for cosmological long GRBs. On the other hand, Chandra X-ray observations carried out during the second radio peak are compatible with the off-axis GRB hypothesis, within the large measurement errors. We conclude that VLBI measurements of the PTF11qcj radio ejecta are needed to unambiguously confirm or rule out the off-axis GRB jet scenario.
© 2019 The American Astronomical Society. Received 2018 June 10; revised 2018 November 22; accepted 2018 December 3; published 2019 February 25. A.C. and N.T.P. acknowledge support from the NSF CAREER award #1455090. A.C. also acknowledges partial support by Chandra Award No. GO7-18065X. J.V. is supported by the GINOP-2.3.2-15-2016-00033 project, which is funded by the Hungarian National Research, Development and Innovation Fund and the European Union. J.C.W. is supported in part by the Samuel T. and Fern Yanagisawa Regents Professorship. A.G.-Y. is supported by the EU via ERC grant No. 725161, the Quantum Universe I-Core program, the ISF, the BSF Transformative program and by a Kimmel award. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
Submitted - 1802.09683.pdf
Published - Palliyaguru_2019_ApJ_872_201.pdf