An Extensive $\textit{Hubble Space Telescope}$ Study of the Offset and Host Light Distributions of Type I Superluminous Supernovae

TL;DR

This study uses Hubble Space Telescope UV imaging to analyze the locations of 65 Type I superluminous supernovae within their host galaxies, revealing distinct spatial distribution patterns compared to other supernovae and gamma-ray bursts.

Contribution

It provides the first extensive analysis of SLSNe spatial distributions within hosts, highlighting differences from other transients and suggesting unique progenitor evolutionary paths.

Findings

SLSNe offsets follow an exponential disk profile but with more large-offset events.

Approximately 40% of SLSNe occur in the dimmest regions of their hosts.

SLSNe locations differ significantly from those of LGRBs and normal core-collapse SNe.

Abstract

We present an extensive $\textit{Hubble Space Telescope}$ ($\textit{HST}$) rest-frame ultraviolet (UV) imaging study of the locations of Type I superluminous supernovae (SLSNe) within their host galaxies. The sample includes 65 SLSNe with detected host galaxies in the redshift range $z\approx 0.05-2$. Using precise astrometric matching with SN images, we determine the distributions of physical and host-normalized offsets relative to the host centers, as well as the fractional flux distribution relative to the underlying UV light distribution. We find that the host-normalized offsets of SLSNe roughly track an exponential disk profile, but exhibit an overabundance of sources with large offsets of $1.5-4$ times their host half-light radius. The SLSNe normalized offsets are systematically larger than those of long gamma-ray bursts (LGRBs), and even Type Ib/c and II SNe. Furthermore, we find that about 40\% of all SLSNe occur in the dimmest regions of their host galaxies (fractional flux of 0), in stark contrast to LGRBs and Type Ib/c and II SNe. We do not detect any significant trends in the locations of SLSNe as a function of redshift, or as a function of explosion and magnetar engine parameters inferred from modeling of their optical lights curves. The significant difference in SLSN locations compared to LGRBs (and normal core-collapse SNe) suggests that at least some of their progenitors follow a different evolutionary path. We speculate that SLSNe arise from massive runaway stars from disrupted binary systems, with velocities of $\sim 10^2$ km s$^{-1}$.