The Optical/Near‐Infrared Light Curves of SN 2002ap for the First 1.5 Years after Discovery

Late-time BVRIJHK photometry of the peculiar Type Ic SN 2002ap, taken between2002 June 12 and 2003 August 29 with the MAGNUM telescope, is presented. Thelight curve decline rate is derived in each band and the color evolution isstudied through comparison with nebular spectra and with SN 1998bw. Using thephotometry, the OIR bolometric light curve is built, extending from beforelight maximum to day 580 after explosion. The light curve has a late-time shapestrikingly similar to that of the hypernova SN 1998bw. The decline rate changesfrom 0.018 mag/day between day 130 and 230 to 0.014 mag/day between day 270 and580. To reproduce the late-time light curve, a dense core must be added to the1-D hypernova model that best fits the early-time observations, bringing theejecta mass from 2.5 Msun to 3 Msun without much change in the kinetic energy,which is 4 times 10^51 ergs. This is similar to the case of other hypernovaeand suggests asymmetry. A large H-band bump developed in the spectral energydistribution after about day 300, probably caused by strong [Si I] 1.646 micronand 1.608 micron emissions. The near-infrared flux contribution increasedsimultaneously from <30% to >50% at day 580. The near-infrared light curveswere compared with those of other Type Ib/c supernovae, among which SN 1983Iseems similar to SN 2002ap both in the near-infrared and in the optical.Comment: 24pages, 9 figures, ApJ in press (10 June 2006, v644 1 issue). Acknowledgements update