Swift J1727.8-1613 reaches 7.6 Crab with strong QPO in Hard X-rays
ATel #16215; David M. Palmer (LANL) and Tyler M. Parsotan (GSFC/UMBC/CRESSTII) report on behalf of the Neil Gehrels Swift Observatory Team
on 29 Aug 2023; 04:16 UT
Credential Certification: David M. Palmer (palmer@lanl.gov)
Subjects: X-ray, Gamma Ray, Black Hole, Transient
The hard X-ray transient Swift J1727.8-1613 (GRB 230824A: GCN #34536, GCN #34540, ATel #16205 etc.) is at an intensity of 7.6 ± 0.4 Crab (15-50 keV) as measured by Swift/BAT's on-board imaging system as of 2023-08-27 05:22 UTC (25 minute accumulation).
In addition, a strong quasi-periodic variation of amplitude ~2000 counts/second (peak-peak, 15-350 keV) is obvious in the raw lightcurves when the source is in BAT's Field Of View.
Fourier analysis of the lightcurve (no barycenter correction) shows a very strong QPO covering the frequency range of roughly 0.46 - 0.88 Hz. No significant strictly-periodic signals are detected.
The
BAT Hard X-ray monitor page for this source is continuously updated with the latest measurements, as they are received on the ground. However, due to excess data volume induced by the current activity of this source, these data products may be somewhat delayed.
