SN 2010ay is a Luminous and Broad-lined Type Ic Supernova within a Low-metallicity Host Galaxy
Price, P. A.; Berger, E.; Cline, T.; Hurley, K.; Kirshner, R. P.; Foley, R. J.; Gehrels, N.; von Kienlin, A.; Chambers, K. C.; Stubbs, C. W.; Magnier, E. A.; Chornock, R.; Golenetskii, S.; Tonry, J. L.; Botticella, M. T.; Mazets, E.; Kaiser, N.; Wainscoat, R. J.; Terada, Y.; Valenti, S.; Soderberg, A. M.; Barthelmy, S. D.; Hodapp, K. W.; Luppino, G. A.; Connaughton, V.; Monet, D. G.; Briggs, M. S.; Boynton, W.; Sanders, N. E.; Chomiuk, L.; Narayan, G.; Kudritzki, R. -P.; Morgan, J. S.; Lupton, R. H.; Smartt, S.; Heasley, J. N.; Jedicke, R.; Grav, T.; Levesque, E. M.; Onaka, P. M.; Waterson, M. F.
United States, United Kingdom, Japan, Russia, Germany, Australia
Abstract
We report on our serendipitous pre-discovery detection and follow-up observations of the broad-lined Type Ic supernova (SN Ic) 2010ay at z = 0.067 imaged by the Pan-STARRS1 3π survey just ~4 days after explosion. The supernova (SN) had a peak luminosity, MR ≈ -20.2 mag, significantly more luminous than known GRB-SNe and one of the most luminous SNe Ib/c ever discovered. The absorption velocity of SN 2010ay is v Si ≈ 19 × 103 km s-1 at ~40 days after explosion, 2-5 times higher than other broad-lined SNe and similar to the GRB-SN 2010bh at comparable epochs. Moreover, the velocity declines ~2 times slower than other SNe Ic-BL and GRB-SNe. Assuming that the optical emission is powered by radioactive decay, the peak magnitude implies the synthesis of an unusually large mass of 56Ni, M Ni = 0.9 M ⊙. Applying scaling relations to the light curve, we estimate a total ejecta mass, M ej ≈ 4.7 M ⊙, and total kinetic energy, EK ≈ 11 × 1051 erg. The ratio of M Ni to M ej is ~2 times as large for SN 2010ay as typical GRB-SNe and may suggest an additional energy reservoir. The metallicity (log (O/H)PP04 + 12 = 8.19) of the explosion site within the host galaxy places SN 2010ay in the low-metallicity regime populated by GRB-SNe, and ~0.5(0.2) dex lower than that typically measured for the host environments of normal (broad-lined) SNe Ic. We constrain any gamma-ray emission with E γ <~ 6 × 1048 erg (25-150 keV), and our deep radio follow-up observations with the Expanded Very Large Array rule out relativistic ejecta with energy E >~ 1048 erg. We therefore rule out the association of a relativistic outflow like those that accompanied SN 1998bw and traditional long-duration gamma-ray bursts (GRBs), but we place less-stringent constraints on a weak afterglow like that seen from XRF 060218. If this SN did not harbor a GRB, these observations challenge the importance of progenitor metallicity for the production of relativistic ejecta and suggest that other parameters also play a key role.