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Radio Non-Detections of SN 2010cu and PSN J13203538+3408222 in IC 883

ATel #3291; Cristina Romero Canizales (IAA-CSIC), Miguel A. Perez-Torres (IAA-CSIC), Antxon Alberdi (IAA-CASIC), Erkki Kankare (Turku), Stuart D. Ryder (AAO), Seppo Mattila (Stockholm)
on 18 Apr 2011; 12:17 UT
Credential Certification: Seppo Mattila (seppo.mattila@utu.fi)

Subjects: Radio, Infra-Red, Supernovae

We report 5 GHz eEVN observations of the luminous infrared galaxy IC 883 intended as a radio follow-up of SN 2010cu (CBET # 2213 and 2286) and PSN J13203538+3408222 (ATel # 3245) that were recently discovered within the nuclear regions of IC 883 by near-IR adaptive-optics observations. The observations were carried out on 23rd March 2011 between 0200UT and 0400UT (total time on source ~1.3 hours) and included the following antennae (diameter, location): Effelsberg (100m, Germany), Jodrell Bank (25m, UK), Medicina (32 m, Italy), Onsala (25 m, Sweden), Torun (32 m, Poland), Westerbork array (14x25 m, NL) and Yebes (40 m, Spain). We achieved a thermal rms of 28 microJy/beam, for a beam size of 10.5x8.5 milliarcsec. The strongest component in the field has a peak flux density at 5 GHz of 3.5 mJy, corresponding to a luminosity of 4.19x10^{28} erg/s/Hz (at an adopted distance of 100 Mpc) and a size similar to the beam, which yields a brightness temperature of approximately 2.7x10^{6} K, indicating a non-thermal origin. The source is located at 13h20m35s.3184, 34o08'22".352 (J2000), about 0.33 arcsec North and 0.14 arcsec East from the near-IR K-band nucleus. No radio source was detected above 3 sigma in the region around the reported positions for either SN 2010cu nor PSN J13203538+3408222. This upper limit corresponds to a 5 GHz luminosity of 1.01x10^{27} erg/s/Hz, which suggests either that PSN J13203538+3408222 is a Type Ib/c SN, which become radio faint in very short time scales (a few months at most), or alternatively, if a Type II SN, we have these likely scenarios: i) the radio emission at 5 GHz is still optically thick, ii) the probable SN is a low luminosity one and thus more sensitive observations are required for its detection. SN 2010cu, which was discovered more than one year ago, has been found to be consistent with a core-collapse SN (CBET 2286). If this SN is a Type II, its non-detection at 5 GHz could indicate that its radio emission at that frequency has entered the optically thin part of the spectrum, having now a luminosity well below 1.0x10^{27} erg/s/Hz, thus being fainter than other well known radio SNe, e.g. SN 1979C. Further high spatial resolution near-IR and radio observations are encouraged.