X-ray and gamma-ray timing study of the gamma-ray burst GRB 211211A observed with Fermi and ASIM
ATel #16706; M. D. Caballero-Garcia (IAA-CSIC), on behalf of a larger collaboration.
on 12 Jul 2024; 14:36 UT
Credential Certification: Maria D. Caballero-Garcia (mcaballero@iaa.es)
Subjects: X-ray, Gamma Ray, Gamma-Ray Burst, Soft Gamma-ray Repeater, Magnetar
We present timing observations and analysis of the very bright and long
GRB 211211A (a.k.a. kilonova candidate) performed by the Atmosphere-Space Interactions
Monitor (ASIM) installed on the International Space Station (ISS) and the Gamma-ray Burst
Monitor (GBM) on-board the Fermi mission.
The very early (<6 s) and high-energy (0.3-20 MeV) ASIM High Energy Detector (HED) light curve shows well-defined peaks
with an increasing quasi-periodic frequency oscillation (QPO) between 2.5-4 Hz
that could be identified with the spin of the neutron star in GRB 211211A (coinciding with the
orbital frequency of the binary merger; Suvorov+22). If confirmed this QPO would consist on the first detection of a
low-frequency QPO (approx. 1 Hz) detected in a ''magnetar''(merger) so far.
This QPO was analyzed in Fermi data carefully and we concluded it to be a tentative detection only. Further and longer
timing X-ray and gamma-ray observations of similar events are needed to confirm the existence of this QPO.
