Bridging the gap between SLSNe and SE-SNe. Multi-wavelength analysis of the SLSN-Ib SN 2024jlc

Abstract

The Type I super-luminous supernova SN~2024jlc (ZTF24aapadbb) exploded on the 25th of May 2024 at $z = 0.039$. Being the closest supernova of this class discovered in recent years and one of the closest ever, represented a rare opportunity to study in detail this type of objects. We performed a multi-wavelength analysis, spanning ten orders of magnitude in frequency, including optical/UV photometry and spectroscopy, soft and hard X-rays, and high-energy $\gamma$-rays. We characterized the event as a slow-evolving and He-rich supernova, with one of the lowest peak luminosities reported for a super-luminous event $M_g\sim-19.37$ mag, and a light curve evolution compatible with both circumstellar interaction and magnetar spin-down models, with noticeable contribution from $^{56}$Ni decay. No significant excess was found in the soft and hard X-ray bands, for which we provide upper-limits on the flux. Additionally, we analyzed two years of \textit{Fermi}-LAT data, from which we report an intriguing hint of a $\gamma$-ray signal at the $\sim 3.6 \sigma$ level, although no firm detection can be claimed. The gamma to optical efficiency ratio, $\eta = 0.38$, is suggestive of the presence of a central-engine scenario, similar to SN~2017egm. Our analysis suggests that SN~2024jlc could bridge the gap between SLSNe and classical stripped-envelope supernovae. While still poorly populated, this bridge could consist of all SLSN-Ib supernovae, with the key difference residing in the powering mechanism.