Discovery and progenitor constraints on the Type Ia supernova 2013gy

• We present an early-phase g-band light curve and visual-wavelength spectra of the normal Type Ia supernova (SN) 2013gy. The light curve is constructed by determining the appropriate S-corrections to transform KAIT natural-system B- and V-band photometry and Carnegie Supernova Project natural-system g-band photometry to the Pan-STARRS1 g-band natural photometric system. A Markov chain Monte Carlo calculation provides a best-fit single power-law function to the first ten epochs of photometry described by an exponent of 2.16(-0.06)(+0.06) and a time of first light of MJD 56629.4(-0.1)(+0.1), which is 1.93(-0.13)(+0.12) days (i.e., <48 h) before the discovery date (2013 December 4.84 UT) and -19.10(-0.13)(+0.12) days before the time of B- band maximum (MJD 56648.5 +/- 0.1). The estimate of the time of first light is consistent with the explosion time inferred from the evolution of the Si II lambda 6355 Doppler velocity. Furthermore, discovery photometry and previous nondetection limits enable us to constrain the companion radius down to R-c <= 4 R-circle dot. In addition to our early-time constraints, we used a deep +235 day nebular-phase spectrum from Magellan/IMACS to place a stripped H-mass limit of <0.018 M-circle dot. Combined, these limits effectively rule out H-rich nondegenerate companions.

Ämnesord

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

Nyckelord

supernovae: general

supernovae: individual SN 2013gy

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