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This content will become publicly available on July 3, 2026

Title: A Near-infrared Search for Helium in the Superluminous Supernova SN 2024ahr
Abstract We present a detailed study of SN 2024ahr, a hydrogen-poor superluminous supernova (SLSN-I), for which we determine a redshift ofz= 0.0861. SN 2024ahr has a peak absolute magnitude ofMg≈Mr≈ −21 mag, rest-frame rise and decline times (50% of peak) of about 40 and 80 days, respectively, and typical spectroscopic evolution in the optical band. Similarly, modeling of the UV/optical light curves with a magnetar spin-down engine leads to typical parameters: an initial spin period of ≈3.3 ms, a magnetic field strength of ≈6 × 1013G, and an ejecta mass of ≈9.5M⊙. Due to its relatively low redshift, we obtained a high signal-to-noise ratio near-IR (NIR) spectrum about 43 rest-frame days postpeak to search for the presence of helium. We do not detect any significant feature at the location of the Heiλ2.058μm feature and place a conservative upper limit of ∼0.05M⊙on the mass of helium in the outer ejecta. We detect broad features of Mgiλ1.575μm and Mgiiλ2.136μm, which are typical of Type Ic SNe, but with higher velocities. Examining the sample of SLSNe-I with NIR spectroscopy, we find that, unlike SN 2024ahr, these events are generally peculiar. This highlights the need for a large sample of prototypical SLSNe-I with NIR spectroscopy to constrain the fraction of progenitors with helium (Ib-like) and without helium (Ic-like) at the time of explosion, and hence the evolutionary path(s) leading to the rare outcome of SLSNe-I.  more » « less
Award ID(s):
2108531 1911225 1911151
PAR ID:
10641405
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publisher / Repository:
The Astrophysical Journal
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
987
Issue:
2
ISSN:
0004-637X
Page Range / eLocation ID:
127
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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