TITLE: GCN CIRCULAR NUMBER: 32802 SUBJECT: GRB 221009A X-ray light-curve and the indication of TeV light-curve DATE: 22/10/19 15:28:45 GMT FROM: Remo Rufinni at ICRA ruffini@icra.it
Y. Aimuratov, L. Becerra, C.L. Bianco, C. Cherubini, S. Filippi, M. Karlica, Liang Li, R. Moradi, F. Rastegar Nia, J.A. Rueda, R. Ruffini, N. Sahakyan, Y. Wang, S.S. Xue, on behalf of the ICRANet team, report:
LHAASO observed more than 5000 very high energy (VHE) photons in GRB 221009A, with the highest energy reaching 18 TeV (GCN 32677). Previously, high energy TeV emissions were also observed in GRB 180720B (Abdalla et al. 2019), 190114C (MAGIC Collaboration 2019), 190829A (H.E.S.S. Collaboration 2021) and 201216C (Blanch et al. GCN 29075). A common feature of these bursts is that the TeV light-curve follows a power-law decay with a similar index as the X-ray light-curve, and the TeV luminosity is tens of percent of the X-ray luminosity (see attached figure 1 and the references of Abdalla et al. 2019, MAGIC Collaboration 2019 and H.E.S.S. Collaboration 2021, Ruffini et al. 2021, Rueda et al. 2022, Rastegarnia et al. 2022, Wang et al. 2022). Here we present the X-ray light-curve of GRB 221009A observed by Swift-XRT (GCN 32651), and the t0 is taken from the Fermi-GBM trigger time (GCN 32636), see attached figure 2, a power-law of index -1.58 is fitted. The shadow region shows 20%-60% of the X-ray luminosity, which is expected to be the 0.3-1 TeV luminosity (17% less luminous for 0.5-18 TeV assuming a power-law spectrum of photon index -2) of this new burst if it shares the same behavior as the previous ones. We encourage further observations, especially the VHE observations, because this burst probably is more luminous than the previous ones, and it will be precious to have a late time (after days) VHE luminosity which was never achieved before, as well as the optical observations for the supernova appearance (GCN 32670, GCN 32780).
Figure 1: http://www.icranet.org/docs/fig1.png Figure 2: http://www.icranet.org/docs/fig2.png