The normal Type Ia SN 2003hv out to very late phases

Abstract

Aims. We study a thermonuclear supernova (SN), emphasizing very late phases.Methods. An extensive dataset for SN 2003hv that covers the flux evolution from maximum light to day +786 is presented. This includes 82 epochs of optical imaging, 24 epochs of near-infrared (NIR) imaging, and 10 epochs of optical spectroscopy. These data are combined with published nebular-phase IR spectra, and the observations are compared to model light curves and synthetic nebular spectra. Results. SN 2003hv is a normal Type Ia supernova (SN Ia) with photometric and spectroscopic properties consistent with its rarely observed B-band decline-rate parameter, Δm 15 (B) = 1.61 ± 0.02. The blueshift of the most isolated [Fe ii] lines in the nebular-phase optical spectrum appears consistent with those observed in the IR at similar epochs. At late times there is a prevalent color evolution from the optical toward the NIR bands. We present the latest-ever detection of a SN Ia in the NIR in Hubble Space Telescope images. The study of the ultraviolet/optical/infrared (UVOIR) light curve reveals that a substantial fraction of the flux is "missing" at late times. Between 300 and 700 days past maximum brightness, the UVOIR light curve declines linearly following the decay of radioactive 56 Co, assuming full and instantaneous positron trapping. At 700 days we detect a possible slowdown of the decline in optical-bands, mainly in the V-band. Conclusions. The data are incompatible with a dramatic infrared catastrophe (IRC). However, the idea that an IRC occurred in the densest regions before 350 days can explain the missing flux from the UVOIR wavelengths and the flat-topped profiles in the NIR. We argue that such a scenario is possible if the ejecta are clumpy. The observations suggest that positrons are most likely trapped in the ejecta.

Whimper of a Bang: Documenting the Final Days of the Nearby Type Ia Supernova 2011fe

“…Using HST and LBT, we followed the light curve of SN 2011fe for an unprecedented 1840 days past t Bmax and over a factor of ∼ 7 million in flux. We present the first clean detection of 57 Leloudas et al 2009;McCully et al 2014;Kerzendorf et al 2014;Graur et al 2016). Fransson & Jerkstrand (2015) claimed to reconcile an IRC with late-time observations of SNe Ia through the redistribution of UV emission into the optical/NIR by non-thermal scattering and fluorescence in order to make up for the reduction in thermally excited flux in the optical/NIR.…”

A reddening-free method to estimate the56Ni mass of Type Ia supernovae

“…It should also be possible to determine the amount of radiation emitted outside the UVOIR region of the spectrum at late phases and a bolometric correction (e.g. Leloudas et al 2009). There are very few objects for which both NIR data to measure t 2 and nebular phase pseudo-bolometric observations are present, making a quantitative comparison for a sample of objects extremely difficult.…”

Two transitional type Ia supernovae located in the Fornax cluster member NGC 1404: SN 2007on and SN 2011iv

“…In the case of the riY JH-band light curves, a transition to a secondary maximum around 20 d past the primary maximum is apparent, which is followed by a linear decline in brightness extending to late phases (e.g., Leloudas et al 2009). For both SNe Ia, the H-band secondary maxima are nearly equal to the luminosity of the primary maxima, while the Y-band secondary maxima exceed the brightness of the primary maxima.…”

“…Additionally, they are brighter than the SN 1991bg-like SNe Ia, despite having similar ∆m 15 (B) values of 1.7-2.0 mag (see, e.g., Ashall et al 2016a). Examples of transitional SNe Ia include SN 2003hv (Leloudas et al 2009), iPTF 13ebh (Hsiao et al 2015), and SN 2015bp (Srivastav et al 2017).…”