Blackbody evolution and circumstellar medium properties of broad-lined H-rich superluminous supernovae
Abstract
Broad-lined H-rich superluminous supernovae (SLSNe II) tend to show signs of interaction, including a UV excess compared to a blackbody function. However, a quantitative analysis of the CSM configuration and the UV excess has so far not been performed for most of the literature sample. Additionally, SN 2023gpw showed signs of asymmetry in its peculiar blackbody and spectral evolution, raising the question of whether similar properties can be found in other SLSNe II. We aim to characterize the circumstellar environment of SLSNe II by searching for signs of asymmetry, quantifying the UV excess, and investigating any IR echoes produced by dust. Diversity among SLSNe II is also explored. We fit blackbody functions to the SEDs of SLSNe II to quantify the UV excess luminosity and its evolution. We use this to investigate mass-loss rates required to produce the excess through interaction. We also investigate the line profiles in SLSN II at late times and compare line velocities to the blackbody radius evolution. We examine public WISE IR images and place constraints on IR echoes. We find mass loss rates of ∼10−4 to ∼0.03 M⊙~yr−1 when assuming all interaction luminosity emerges in the UV, i.e., conservative lower limits for the total mass loss rate. Radii calculated from line velocities in late-time spectra are mostly too large for a spherical interaction photosphere, only compatible with the blackbody radius evolution if the CSM is non-spherical with a low filling factor. This is in some cases supported by a mismatch between spectroscopic and blackbody expansion velocities. Considerable diversity is seen in the sample, probably as a result of different viewing angles and CSM masses. WISE images seem too shallow to observe IR echoes in SLSNe II beyond z∼0.1, but in the nearest event, SN 2020jhm, a likely IR echo is detected, suggesting pre-existing dust.
Related
- Circumbinary discs as the origin of circumstellar material around interacting H-poor supernovae and fast blue optical transients
- Not So Heavy Metal I: Low Metallicity Enhances the Rate of high-redshift Superluminous Supernovae
- Probing Feebly Interacting Particles with 511 keV Line from Circumstellar Medium of Supernovae
- On the Evolution of Circumstellar Disks Modified by the Presence of a Binary
- On the Evolution of Circumstellar Disks Modified by the Presence of a Binary
BibTeX
@misc{kangas2026blackbody,
title = {{Blackbody evolution and circumstellar medium properties of broad-lined H-rich superluminous supernovae}},
author = {Tuomas Kangas and Takashi Nagao and Uliana Pylypenko and Steve Schulze and Lin Yan},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.16527},
eprint = {2610.16527},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.16527},
}
RIS
TY - UNPB
TI - Blackbody evolution and circumstellar medium properties of broad-lined H-rich superluminous supernovae
AU - Tuomas Kangas
AU - Takashi Nagao
AU - Uliana Pylypenko
AU - Steve Schulze
AU - Lin Yan
PY - 2026
DA - 2026/10/12
PB - arXiv
DO - 10.48550/arxiv.2610.16527
UR - https://arxiv.org/abs/2610.16527
AB - Broad-lined H-rich superluminous supernovae (SLSNe II) tend to show signs of interaction, including a UV excess compared to a blackbody function. However, a quantitative analysis of the CSM configuration and the UV excess has so far not been performed for most of the literature sample. Additionally, SN 2023gpw showed signs of asymmetry in its peculiar blackbody and spectral evolution, raising the question of whether similar properties can be found in other SLSNe II. We aim to characterize the circumstellar environment of SLSNe II by searching for signs of asymmetry, quantifying the UV excess, and investigating any IR echoes produced by dust. Diversity among SLSNe II is also explored. We fit blackbody functions to the SEDs of SLSNe II to quantify the UV excess luminosity and its evolution. We use this to investigate mass-loss rates required to produce the excess through interaction. We also investigate the line profiles in SLSN II at late times and compare line velocities to the blackbody radius evolution. We examine public WISE IR images and place constraints on IR echoes. We find mass loss rates of ∼10^−4 to ∼0.03 M_⊙~yr^−1 when assuming all interaction luminosity emerges in the UV, i.e., conservative lower limits for the total mass loss rate. Radii calculated from line velocities in late-time spectra are mostly too large for a spherical interaction photosphere, only compatible with the blackbody radius evolution if the CSM is non-spherical with a low filling factor. This is in some cases supported by a mismatch between spectroscopic and blackbody expansion velocities. Considerable diversity is seen in the sample, probably as a result of different viewing angles and CSM masses. WISE images seem too shallow to observe IR echoes in SLSNe II beyond z∼0.1, but in the nearest event, SN 2020jhm, a likely IR echo is detected, suggesting pre-existing dust.
ER -