SN 2018fif: The Explosion of a Large Red Supergiant Discovered in Its Infancy by the Zwicky Transient Facility

Abstract

High cadence transient surveys are able to capture supernovae closer to their first light than before. Applying analytical models to such early emission, we can constrain the progenitor stars properties. In this paper, we present observations of SN 2018 fif (ZTF18abokyfk). The supernova was discovered close to first light and monitored by the Zwicky Transient Facility (ZTF) and the Neil Gehrels Swift Observatory. Early spectroscopic observations suggest that the progenitor of SN 2018 fif was surrounded by relatively small amounts of circumstellar material (CSM) compared to all previous cases. This particularity, coupled with the high cadence multiple-band coverage, makes it a good candidate to investigate using shock-cooling models. We employ the SOPRANOS code, an implementation of the model by Sapir & Waxman (2017). Compared with previous implementations, SOPRANOS has the advantage of including a careful account of the limited temporal validity domain of the shockcooling model. We find that the progenitor of SN 2018 fif was a large red supergiant, with a radius of R = 1174 +208 −81 R and an ejected mass of M ej = 5.6 +9.1 −1.0 M. Our model also gives information on the explosion epoch, the progenitor inner structure, the shock velocity and the extinction. The large radius differs from previously modeled objects, and the difference could be either intrinsic or due to the relatively small amount of CSM around SN 2018 fif, perhaps making it a "cleaner" candidate for applying shock-cooling analytical models.

The GALEX-PTF experiment: II. supernova progenitor radius and energetics via shock-cooling modeling

“…SOPRANOS has two implementations. SOPRANOS-grid, described in this paper and written in MATLAB, which samples the parameter space by calculating the likelihood of a discrete grid of models, and SOPRANOS-nested, described on Soumagnac et al (2020) and written in python, which uses the nested sampling algorithm (Skilling 2004(Skilling , 2006Higson et al 2019;Speagle 2020) to dynamically sample the model parameter space.…”

“…First results of the SOPRANOS algorithm were already reported in Soumagnac et al (2020) which used SOPRANOS-nested. Here we use SOPRANOS-grid.…”

“…This requires some priors, which have to be selected carefully in order not to bias the results. Davies et al (2018) explored the population of Red Super Giants in the Small and Large Maglanic Clouds and derived their radius out of the measured luminosity and temperatures (See Figure 10 on Soumagnac et al 2020). Most of the RSGs have radii smaller than 1100 solar radii, and only a few have radii in the range of 1100-1400 solar radii.…”

“…Only a few SNe were detected by space telescopes in shorter wavelengths, often by coincidence (e.g. Arnett et al 1989;Schmidt et al 1993;Camp et al 2013;Gezari et al 2008Gezari et al , 2010Schawinski et al 2008;Soderberg et al 2008;Ofek et al 2010;Arcavi et al 2011;Gal-Yam et al 2011;Cao et al 2013;Soumagnac et al 2020). Theoretical models predict that the earliest emission from CC SNe is a burst of radiation occurring when the explosion shock breaks out of the stellar surface (the shock breakout flare).…”

The GALEX-PTF Experiment. II. Supernova Progenitor Radius and Energetics via Shock-cooling Modeling

“…Most previous, existing, and planned SN surveys such as the Palomar Transient Factory (PTF; Law et al 2009;Rau et al 2009), the Large Synoptic Survey Telescope (Ivezić et al 2019), the All Sky Automated Survey for Supernovae (Shappee et al 2014), the Asteroid Terrestrial-impact Last Alert System (Tonry et al 2018), the Large Array Survey Telescope (Ofek & Ben-Ami 2020), and the Zwicky Transient Facility (Bellm 2014) are limited to visible-near-infrared wavelengths. Only a few SNe have been detected by space telescopes in shorter wavelengths, often by coincidence (e.g., Arnett et al 1989;Schmidt et al 1993;Camp et al 2013;Gezari et al 2008Gezari et al , 2010Schawinski et al 2008;Soderberg et al 2008;Ofek et al 2010;Arcavi et al 2011;Gal-Yam et al 2011;Cao et al 2013;Soumagnac et al 2020). Theoretical models predict that the earliest emission from CC SNe is a burst of radiation occurring when the explosion shock breaks out of the stellar surface (the shock breakout flare).…”