A VLA Survey of Late-time Radio Emission from Superluminous Supernovae and the Host Galaxies

TL;DR

This study uses late-time 3 GHz radio observations of 23 superluminous supernovae and their host galaxies to investigate radio emission, star formation, and potential jet or pulsar wind nebula signatures, providing insights into their environments and explosion mechanisms.

Contribution

It presents one of the largest samples of late-time radio data for SLSNe, constrains models of jets and magnetar-powered nebulae, and compares radio-derived star formation rates with UV-NIR estimates.

Findings

Radio emission detected from one SLSN and five hosts.

Most hosts do not show significant obscured star formation.

Models with high energies and densities are excluded based on upper limits.

Abstract

We present the results of 3 GHz radio continuum observations of 23 superluminous supernovae (SLSNe) and their host galaxies by using the Karl G. Jansky Very Large Array conducted 5-21 years after the explosions. The sample consists of 15 Type I and 8 Type II SLSNe at z < 0.3, providing one of the largest sample of SLSNe with late-time radio data. We detected radio emission from one SLSN (PTF10hgi) and 5 hosts with a significance of >5$\sigma$. No time variability is found in late-time radio light curves of the radio-detected sources in a timescale of years except for PTF10hgi, whose variability is reported in a separate study. Comparison of star-formation rates (SFRs) derived from the 3 GHz flux densities with those derived from SED modeling based on UV-NIR data shows that four hosts have an excess of radio SFRs, suggesting obscured star formation. Upper limits for undetected hosts and stacked results show that the majority of the SLSN hosts do not have a significant obscured star formation. By using the 3 GHz upper limits, we constrain the parameters for afterglows arising from interaction between initially off-axis jets and circumstellar medium (CSM). We found that the models with higher energies ($E_{\rm iso} \gtrsim$ several $\times 10^{53}$ erg) and CSM densities ($n \gtrsim 0.01$ cm$^{-3}$) are excluded, but lower energies or CSM densities are not excluded with the current data. We also constrained the models of pulsar wind nebulae powered by a newly born magnetar for a subsample of SLSNe with model predictions in the literature.