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The Radio Evolution of SN 2001gd

Stockdale, Christopher J. and Williams, Christopher L. and Weiler, Kurt W. and Panagia, Nino and Sramek, Richard A. and Van Dyk, Schuyler D. and Kelley, Matthew T. (2007) The Radio Evolution of SN 2001gd. Astrophysical Journal, 671 (1). pp. 689-694. ISSN 0004-637X.

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We present the results of observations of the radio emission from SN 2001gd in NGC5033 from 2002 February 8 through 2006 September 25. The data were obtained using the VLA at wavelengths of 1.3 cm (22.4 GHz), 2 cm (14.9 GHz), 3.6 cm (8.4 GHz), 6 cm (4.9 GHz), and 20 cm (1.5 GHz), with one upper limit at 90 cm (0.3 GHz). In addition, one detection has been provided by the GMRT at 21 cm (1.4 GHz). SN 2001gd was discovered in the optical well past maximum light, so that it was not possible to obtain many of the early radio "turn-on" measurements that are important for estimating the local CSM properties. Only at 20 cm were turn-on data available. However, our analysis and fitting of the radio light curves, along with the assumption that the Type IIb SN 2001gd resembles the much better studied Type IIb SN 1993J, enables us to describe the radio evolution as being very regular through day ~550 and consistent with a nonthermal-emitting model with a thermal absorbing CSM. The presence of SSA at early times is implied by the data, but determination of the exact relationship between the SSA component from the emitting region and the free-free absorption component from the CSM is not possible, as there are insufficient early measurements to distinguish between models. After day ~550, the radio emission exhibits a dramatically steeper decline rate, which, assuming similarity to SN 1993J, can be described as an exponential decrease with an e-folding time of 500 days. We interpret this abrupt change in the radio flux density decline rate as implying a transition of the shock front into a more tenuous region of circumstellar material. A similar change in radio evolution has been seen earlier in other SNe, such as SN 1988Z, SN 1980K, and SN 1993J.

Item Type:Article
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Van Dyk, Schuyler D.0000-0001-9038-9950
Additional Information:© 2007 The American Astronomical Society. Received 2007 July 8; accepted 2007 August 7. K.W.W. wishes to thank the Office of Naval Research (ONR) for the 6.1 funding supporting his research. C. J. S. is a Cottrell Scholar of the Research Corporation, and work on this project has been supported by the NASA Wisconsin Space Grant Consortium. N. P. is Astronomer Emeritus at the Space Telescope Science Institute (STScI), which kindly provided research facilities and partial support for this work. Additional information and data on radio supernovae can be found at and linked pages.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Office of Naval Research (ONR)UNSPECIFIED
Wisconsin Space Grant ConsortiumUNSPECIFIED
Space Telescope Science InstituteUNSPECIFIED
Cottrell Scholar of Research CorporationUNSPECIFIED
Subject Keywords:galaxies : individual (NGC5033); radio continuum : stars; supernovae : individual (SN 2001gd)
Issue or Number:1
Record Number:CaltechAUTHORS:20091202-134234336
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Official Citation:The Radio Evolution of SN 2001gd Christopher J. Stockdale, Christopher L. Williams, Kurt W. Weiler, Nino Panagia, Richard A. Sramek, Schuyler D. Van Dyk, and Matthew T. Kelley 2007 ApJ 671 689-694 doi: 10.1086/522584
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:16859
Deposited By: Tony Diaz
Deposited On:23 Dec 2009 03:55
Last Modified:03 Oct 2019 01:18

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