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An early and comprehensive millimetre and centimetre wave and X-ray study of SN 2011dh: a non-equipartition blast wave expanding into a massive stellar wind

2013; Oxford University Press; Volume: 436; Issue: 2 Linguagem: Inglês

10.1093/mnras/stt1645

1365-2966

A. Horesh, Chris Stockdale, D. B. Fox, D. A. Frail, John M. Carpenter, S. R. Kulkarni, E. O. Ofek, A. Gal‐Yam, M. M. Kasliwal, I. Arcavi, R. Quimby, S. B. Cenko, P. Nugent, J. S. Bloom, Nicholas M. Law, D. Poznanski, E. Gorbikov, David Polishook, O. Yaron, S. D. Ryder, K. W. Weiler, F. E. Bauer, Schuyler D. Van Dyk, S. Immler, N. Panagia, D. Pooley, N. E. Kassim,

Pulsars and Gravitational Waves Research

Only a handful of supernovae (SNe) have been studied in multi-wavelength from radio to X-rays, starting a few days after explosion. The early detection and classification of the nearby type IIb SN2011dh/PTF11eon in M51 provides a unique opportunity to conduct such observations. We present detailed data obtained at the youngest phase ever of a core-collapse supernova (days 3 to 12 after explosion) in the radio, millimeter and X-rays; when combined with optical data, this allows us to explore the early evolution of the SN blast wave and its surroundings. Our analysis shows that the expanding supernova shockwave does not exhibit equipartition (e_e/e_B ~ 1000), and is expanding into circumstellar material that is consistent with a density profile falling like R^-2. Within modeling uncertainties we find an average velocity of the fast parts of the ejecta of 15,000 +/- 1800 km/s, contrary to previous analysis. This velocity places SN 2011dh in an intermediate blast-wave regime between the previously defined compact and extended SN IIb subtypes. Our results highlight the importance of early (~ 1 day) high-frequency observations of future events. Moreover, we show the importance of combined radio/X-ray observations for determining the microphysics ratio e_e/e_B.