[vsnet-grb-info 20968] GRB 180728A: A long GRB of the X-ray flash (XRF) subclass, expecting supernova appearance

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23066
SUBJECT: GRB 180728A: A long GRB of the X-ray flash (XRF) subclass, expecting supernova appearance
DATE:    18/07/31 10:29:39 GMT
FROM:    Remo Rufinni at ICRA  <ruffini at icra.it>

R. Ruffini, Y. Aimuratov, C. L. Bianco, Y. C. Chen, D. M. Fuksman, M. Karlica, R. Moradi, D. Primorac, J.A. Rueda, N. Sahakyan, Y. Wang, on behalf of the ICRANet team, report:

GRB 180728A has T90=6.4s (P. Veres et al., GCN 23053), peak energy 142 (-15.+20) keV, and isotropic energy (2.33 +/- 0.10)x10^51 erg (D. Frederiks, et al., GCN 23061). It presents the typical characteristic of a subclass of long GRBs called X-ray flashes (XRFs, see Ruffini et al., ApJ 832 (2016) 136), originating from a tight binary of a FeCO Core undergoing a supernova explosion in presence of a companion neutron star (NS) which undergoes hypercritical accretion. The outcome (see Fig. [1]) is a new binary composed by a more massive NS (MNS) and a newly born NS (vNS). Using the averaged observed value (Cano et al., 2016), and considering the redshift z=0.117 (A. Rossi et al., GCN 23055), a bright optical signal will peak at 14.7 +/- 2.9 days after the trigger (12 August 2018, uncertainty from August 9th to August 15th) at the location of RA 253.56472 and DEC -54.04451, with an uncertainty 0.43 arc sec (S. J. LaPorte et al., GCN 23064). The follow-up observations, especially the optical bands for the SN, as well as attention to binary NS pulsar behaviors in the X-ray afterglow emission, are recommended.


[1] Link: http://www.icranet.org/documents/180728A_f1.png

Figure Caption: Snapshot of the binary system formed by the MNS and by the vNS together with the SN ejecta density. See for details Fig. 7 of Ruffini et al., ApJ 832 (2016) 136.