2025ApJ...995L..59K

Query : 2025ApJ...995L..59K

2025ApJ...995L..59K - Astrophys. J., 995, L59 (2025/December-3)

ZTF25abjmnps (AT2025ulz) and S250818k: A Candidate Superkilonova from a Subthreshold Subsolar Gravitational-wave Trigger.

KASLIWAL M.M., AHUMADA T., STEIN R., KARAMBELKAR V., HALL X.J., SINGH A., FREMLING C., METZGER B.D., BULLA M., SWAIN V., ANTIER S., PILLAS M., BUSMANN M., FREEBURN J., KARPOV S., BOCHENEK A., O'CONNOR B., PERLEY D.A., AKL D., ANAND S., TOIVONEN A., ROSE S., JEGOU DU LAZ T., LIU C., DAS K., SHARMA CHAUDHARY S., BARNA T., SAIKIA A.P., ANDREONI I., BELLM E.C., BHALERAO V., CENKO S.B., COUGHLIN M.W., GRUEN D., KASEN D., MILLER A.A., NISSANKE S., PALMESE A., SOLLERMAN J., SRAVAN N., ANUPAMA G.C., BANERJEE S., BARWAY S., BLOOM J.S., CABRERA T., CHEN T., COPPERWHEAT C., CORSI A., DEKANY R., EARLEY N., GRAHAM M., HELLO P., HELOU G., HU L., KINI Y., MAHABAL A., MASCI F., MOHAN T., PLETSKOVA N., PURDUM J., QIN Y.-J., REHEMTULLA N., SALGUNDI A. and WANG Y.

Abstract (from CDS):

On 2025 August 18, the LIGO-Virgo-KAGRA collaboration reported gravitational waves from a subthreshold binary neutron star merger. If astrophysical, this event would have a surprisingly low chirp mass, suggesting that at least one neutron star was below a solar mass. The Zwicky Transient Facility mapped the coarse localization and discovered a transient, ZTF 25abjmnps (AT2025ulz), which was spatially and temporally coincident with the gravitational-wave trigger. The first week of follow-up suggested properties reminiscent of a GW170817-like kilonova. Subsequent follow-up suggests properties most similar to a young, stripped-envelope, Type IIb supernova. Although we cannot statistically rule out chance coincidence, we undertake due diligence analysis to explore the possible association between ZTF 25abjmnps and S250818k. Theoretical models have been proposed wherein subsolar neutron star(s) may form (and subsequently merge) via accretion-disk fragmentation or core fission inside a core-collapse supernova-i.e., a “superkilonova.” Here, we qualitatively discuss our multiwavelength dataset in the context of the superkilonova picture. Future higher-significance gravitational-wave detections of subsolar neutron star mergers with extensive electromagnetic follow-up would conclusively resolve this tantalizing multimessenger association.

Abstract Copyright: © 2025. The Author(s). Published by the American Astronomical Society.

Journal keyword(s): Neutron stars - Compact objects - Transient sources - Core-collapse supernovae - Surveys - Gravitational waves

Status at CDS : Large table(s) will be appraised for possible ingestion in VizieR.

Simbad objects: 16

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Number of rows : 16
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 SN 2019npv SN* 00 53 32.316 -23 49 58.50           SNIbc 7 0
2 GrW 190814 GWE 00 55.8 -27 05           ~ 433 0
3 SN 2019wxt SN* 01 55 41.94 +31 25 04.4           ~ 14 0
4 AT 2025uow ev 03 33 31.096 -30 05 46.61           ~ 1 0
5 SN 1993J SN* 09 55 24.77476 +69 01 13.7026   10.8 12.0     SNIIb 1507 1
6 SN 2013df SN* 12 26 29.33 +31 13 38.3           SNIIb 142 1
7 GrW 170817 GWE 13 09 48.0850 -23 22 53.343           ~ 2683 0
8 SN 2011dh SN* 13 30 05.10555 +47 10 10.9227           SNIIb 445 1
9 SN 2025uic SN* 15 14 44.827 +14 22 17.05           SNII 1 0
10 AT 2025wxt ev 15 40 27.377 +26 52 14.74           ~ 1 0
11 SN 2025uxs SN* 15 44 14.345 +27 28 41.95           SNIa 2 0
12 SN 2025ulz SN* 15 51 54.201 +30 54 08.67           SNIIb 6 0
13 SN 2025uso SN* 16 16 57.433 +35 03 20.81           SNIIb 3 0
14 SN 2025vfa SN* 16 25 00.394 +45 03 13.43           SNIa 1 0
15 AT 2025unk ev 16 25 33.477 +40 43 49.40           ~ 1 0
16 AT 2025uxu ev 18 02 45.942 +56 29 30.02           ~ 1 0

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