Early ultraviolet emission in the Type Ia supernova LSQ12gdj: No evidence for ongoing shock interaction
2014 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 445, no 1, 30-48 p.Article in journal (Refereed) Published
We present photospheric-phase observations of LSQ12gdj, a slowly declining, UV-bright Type Ia supernova. Classified well before maximum light, LSQ12gdj has extinction-corrected absolute magnitude M-B = -19.8, and pre-maximum spectroscopic evolution similar to SN 1991T and the super-Chandrasekhar-mass SN 2007if. We use ultraviolet photometry from Swift, ground-based optical photometry, and corrections from a near-infrared photometric template to construct the bolometric (1600-23 800 angstrom) light curve out to 45 d past B-band maximum light. We estimate that LSQ12gdj produced 0.96 +/- 0.07 M-circle dot of Ni-56, with an ejected mass near or slightly above the Chandrasekhar mass. As much as 27 per cent of the flux at the earliest observed phases, and 17 per cent at maximum light, is emitted bluewards of 3300 angstrom. The absence of excess luminosity at late times, the cutoff of the spectral energy distribution bluewards of 3000 angstrom and the absence of narrow line emission and strong Na I D absorption all argue against a significant contribution from ongoing shock interaction. However, similar to 10 per cent of LSQ12gdj's luminosity near maximum light could be produced by the release of trapped radiation, including kinetic energy thermalized during a brief interaction with a compact, hydrogen-poor envelope (radius < 10(13) cm) shortly after explosion; such an envelope arises generically in double-degenerate merger scenarios.
Place, publisher, year, edition, pages
2014. Vol. 445, no 1, 30-48 p.
circumstellar matter, supernovae: general, supernovae: individual: SN 2003fg, SN 2007if, SN 2009dc, LSQ12gdj, white dwarfs
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:su:diva-109958DOI: 10.1093/mnras/stu1723ISI: 000343827700003OAI: oai:DiVA.org:su-109958DiVA: diva2:769126