Four (Super)luminous Supernovae from the First Months of the ZTF Survey

TL;DR

This paper reports on four hydrogen-poor superluminous supernovae discovered by ZTF, highlighting their diverse properties, rapid rise times, and potential implications for understanding supernova mechanisms.

Contribution

First detailed analysis of four SLSN-I from ZTF, revealing diverse behaviors and challenging existing models of superluminous supernovae.

Findings

SN2018bgv is the fastest-rising SLSN-I with a 10-day rise time.

SN2018don shows strong light curve undulations and red colors.

One supernova may be powered by a low-mass magnetar or circumstellar interaction.

Abstract

We present photometry and spectroscopy of four hydrogen-poor luminous supernovae discovered during the two-month science commissioning and early operations of the Zwicky Transient Facility (ZTF) survey. Three of these objects, SN2018bym (ZTF18aapgrxo), SN2018avk (ZTF18aaisyyp) and SN2018bgv (ZTF18aavrmcg) resemble typical SLSN-I spectroscopically, while SN2018don (ZTF18aajqcue) may be an object similar to SN2007bi experiencing considerable host galaxy reddening, or an intrinsically long-lived, luminous and red SN Ic. We analyze the light curves, spectra, and host galaxy properties of these four objects and put them in context of the population of SLSN-I. SN2018bgv stands out as the fastest-rising SLSN-I observed to date, with a rest-frame g-band rise time of just 10 days from explosion to peak -- if it is powered by magnetar spin-down, the implied ejecta mass is only ~1 M$_{\odot}$. SN2018don also displays unusual properties -- in addition to its red colors and comparatively massive host galaxy, the light curve undergoes some of the strongest light curve undulations post-peak seen in a SLSN-I, which we speculate may be due to interaction with circumstellar material. We discuss the promises and challenges of finding SLSNe in large-scale surveys like ZTF given the observed diversity in the population.