EARLY RADIO AND X-RAY OBSERVATIONS OF THE YOUNGEST NEARBY TYPE Ia SUPERNOVA PTF 11kly (SN 2011fe)

TLDR: In this article, the authors present the analysis of radio and X-ray observations, yielding the tightest constraints yet placed on the pre-explosion mass-loss rate from the progenitor system of this supernova.

Abstract: On August 24 (UT) the Palomar Transient Factory (PTF) discovered PTF11kly (SN 2011fe), the youngest and most nearby type Ia supernova (SN Ia) in decades. We followed this event up in the radio (centimeter and millimeter bands) and X-ray bands, starting about a day after the estimated explosion time. We present our analysis of the radio and X-ray observations, yielding the tightest constraints yet placed on the pre-explosion mass-loss rate from the progenitor system of this supernova. We find a robust limit of M(raised dot) less than or equal to 10(exp -8) (w /100 kilometers per second ) solar mass yr(exp -1) from sensitive X-ray non-detections, as well as a similar limit from radio data, which depends, however, on assumptions about microphysical parameters. We discuss our results in the context of single-degenerate models for SNe Ia and find that our observations modestly disfavor symbiotic progenitor models involving a red giant donor, but cannot constrain systems accreting from main sequence or sub-giant stars, including the popular supersoft channel. In view of the proximity of PTF11kly and the sensitivity of our prompt observations we would have to wait for a long time (decade or longer) in order to more meaningfully probe the circumstellar matter of Ia supernovae.

Figures

Table 1 Log of Radio Observations

Table 2 Log of X-Ray Observations

Figure 1. 21 cm image of M101 taken with WSRT on UT 2011 August 31. SN position is shown by the cross. (A color version of this figure is available in the online journal.)

Figure 2. Model light curves for four different values of B = Ṁ/w where 2 = B e , w is the wind velocity, and Ṁ is the mass-loss rate (see also Section 3.1). We assume the following normalization, = 0.1, w = 107 cm s−1, and vs = 4×109 cm s−1. Model light curves for four values of B = [10−6, 10−7, 10−8, 10−9](0.1/ )w7 M yr−1 are shown. Top panel is for X band (8 GHz) while bottom panel is for C (5 GHz) band. The open triangles in both panels show upper limits from Panagia et al. (2006). The gray triangle in the top panel is the best limit from Panagia et al. (2006) while that in the bottom panel is the upper limit from Hancock et al. (2011). Red triangles are measurements of PTF11kly and presented in Table 1.