.png){kind=icon}
.png){kind=icon}
Return
AT2025ulz and S250818k: Leveraging DESI Spectroscopy in the Hunt for a Kilonova Associated with a Subsolar-mass Gravitational-wave Candidate
.png){kind=icon}
PRE
AI
X
A
B
D
M
G
L
H
J
A
S
J
S
D
T
F
C
A
A
D
F
S
A
J
G
L
J
T
A
L
C
M
L
A
M
A
M
J
S
P
I
R
M
D
S
D
G
W
R
H
DOI：10.3847/2041-8213/ae4338.png)
.png){kind=icon}
Original request for help.png){kind=icon}
Share.png){kind=icon}
Save
Abstract
En 中文
On 2025 August 18, the LIGO-Virgo-KAGRA collaboration reported a subthreshold gravitational-wave candidate detection consistent with a subsolar-mass neutron star merger, denoted S250818k. An optical transient, AT2025ulz, was discovered within the localization region. AT2025ulz initially appeared to meet the expected behavior of kilonova emission, the telltale signature of a binary neutron star merger. The transient subsequently rebrightened after similar to 5 days and was classified as a Type IIb supernova. In this work, we analyze the observations of its host galaxy obtained by the Dark Energy Spectroscopic Instrument (DESI). From the DESI spectrum, we obtain a secure redshift of z = 0.084840 +/- 0.000006. If S250818k has an astrophysical origin, this places the transient within 2 sigma of the gravitational-wave distance and results in an integral overlap between the gravitational-wave alert and the transient location of log10I approximate to 3.9-4.2 . Our analysis of the host galaxy's spectral energy distribution reveals a star-forming, dusty galaxy with stellar mass similar to 1010 M circle dot, broadly consistent with the population of both short gamma-ray bursts and core-collapse supernova host galaxies. We also present our follow-up of DESI-selected candidate host galaxies using the Fraunhofer Telescope at the Wendelstein Observatory, and show the promise of DESI for associating or rejecting candidate electromagnetic counterparts to gravitational-wave alerts. These results emphasize the value of DESI's extensive spectroscopic dataset in rapidly characterizing host galaxies, enabling spectroscopic host subtraction, and guiding targeted follow-up.
Keywords:
GAMMA-RAY BURST
HOST GALAXIES
ELECTROMAGNETIC COUNTERPART
STAR-FORMATION
HUBBLE CONSTANT
COLLAPSAR DISKS
X-RAY
EMISSION
STELLAR
MERGER
Journal
IF:
11.7
Papers:
1.2W
Citations:
5.9W
Organization
Cited Papers