2007/03/29 by S. Immler, P. J. Brown, Peter Milne +27 · 2 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Gamma-ray bursts and supernovae #astro-ph
paper · pdf · doi:10.1086/518466
published as Astrophys.J.664:435-442,2007 · 8 pages, 5 figures, accepted for publication in ApJ
arxiv created 2007/03/29 · openalex publication_date 2007/07/10 · arxiv updated 2010/03/19 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/04
We present results on the X-ray and optical/UV emission from the Type II-P supernova (SN) 2006bp and the interaction of the SN shock with its environment, obtained with the X-Ray Telescope (XRT) and UV/Optical Telescope (UVOT) on board Swift . SN 2006bp is detected in X-rays at a 4.5 σ level of significance in the merged XRT data from days 1 to 12 after the explosion. If the 0.2-10 keV band X-ray luminosity of L 0.2-10 = (1.8 ± 0.4) × 10 39 ergs s -1 is caused by interaction of the SN shock with circumstellar material (CSM) deposited by a stellar wind from the progenitor's companion star, a mass-loss rate of ≈ (1 × 10 -5 M ☉ yr -1 )( v w /10 km s -1 ) is inferred. The mass-loss rate is consistent with the nondetection in the radio with the VLA on days 2, 9, and 11 after the explosion and is characteristic of a red supergiant progenitor with a mass of ≈12-15 M ☉ prior to the explosion. The Swift data further show a fading of the X-ray emission starting around day 12 after the explosion. In combination with a follow-up XMM-Newton observation obtained on day 21 after the explosion, an X-ray rate of decline of L X ∝ t - n with index n = 1.2 ± 0.6 is inferred. Since no other SN has been detected in X-rays prior to the optical peak, and since Type II-P SNe have an extended "plateau" phase in the optical, we discuss the scenario that the X-rays might be due to inverse Compton scattering of photospheric optical photons off relativistic electrons produced in circumstellar shocks. However, due to the high required value of the Lorentz factor (≈10-100), which is inconsistent with the ejecta velocity inferred from optical line widths, we conclude that inverse Compton scattering is an unlikely explanation for the observed X-ray emission.