23 GHz VLBI Observations of SN 2008ax
| Autor: | Marti-Vidal, I., Marcaide, J. M., Alberdi, A., Guirado, J. C., Perez-Torres, M. A., Ros, E., Shapiro, I. I., Beswick, R. J., Muxlow, T. W. B., Pedlar, A., Argo, M. K., Immler, S., Panagia, N., Stockdale, C. J., Sramek, R. A., Van Dyk, S., Weiler, K. W. |
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| Rok vydání: | 2009 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1051/0004-6361/200912034 |
| Popis: | We report on phase-referenced 23 GHz Very-Long-Baseline-Interferometry (VLBI) observations of the type IIb supernova SN 2008ax, made with the Very Long Baseline Array (VLBA) on 2 April 2008 (33 days after explosion). These observations resulted in a marginal detection of the supernova. The total flux density recovered from our VLBI image is 0.8$\pm$0.3 mJy (one standard deviation). As it appears, the structure may be interpreted as either a core-jet or a double source. However, the supernova structure could be somewhat confused with a possible close by noise peak. In such a case, the recovered flux density would decrease to 0.48$\pm$0.12 mJy, compatible with the flux densities measured with the VLA at epochs close in time to our VLBI observations. The lowest average expansion velocities derived from our observations are $(1.90 \pm 0.30) \times 10^5$ km s$^{-1}$ (case of a double source) and $(5.2 \pm 1.3) \times 10^4$ km s$^{-1}$ (taking the weaker source component as a spurious, close by, noise peak, which is the more likely interpretation). These velocities are 7.3 and 2 times higher, respectively, than the maximum ejecta velocity inferred from optical-line observations. Comment: 4 pages, 3 figures. Accepted in A&A on 24/03/2009 |
| Databáze: | arXiv |
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