Evidence for rapid variability in the optical light curve of the Type Ia SN 2014J^⋆,⋆⋆

IAASARS, National Observatory of Athens, 15236 Penteli, Greece
e-mail: bonanos@astro.noa.gr

Received: 26 November 2014
Accepted: 25 October 2015

Abstract

We present results of high-cadence monitoring of the optical light curve of the nearby, Type Ia SN 2014J in M 82, using the 2.3 m Aristarchos telescope. B and V-band photometry on days 15–18 after t_max(B) was obtained with a cadence of 2 min per band, revealing evidence for rapid variability at the 0.02–0.05 mag level on timescales of 15–60 min on all four nights. The decline slope was measured as steeper in the B-band than in the V-band, and to steadily decrease in both bands from 0.15 mag day^-1 (night 1) to 0.04 mag day^-1 (night 4) in V, and from 0.19 mag day^-1 (night 1) to 0.06 mag day^-1 (night 4) in B, corresponding to the onset of the secondary maximum. We propose that rapid variability could be due to one or a combination of the following scenarios: the clumpiness of the ejecta, their interaction with circumstellar material, the asymmetry of the explosion, or the mechanism causing the secondary maximum in the near-infrared light curve. We encourage the community to undertake high-cadence monitoring of future, nearby and bright supernovae to investigate the intraday behaviour of their light curves.