TITLE:   GCN CIRCULAR
NUMBER:  32169
SUBJECT: GRB 220527A: A BdHN I with a clear UPE phase
DATE:    22/06/06 15:33:00 GMT
FROM:    Remo Rufinni at ICRA  <ruffini@icra.it>

R. Ruffini, Y. Aimuratov, L. Becerra, C.L. Bianco, Y.-C. Chen, C.
Cherubini, S. Eslamzadeh, S. Filippi, M. Karlica, L. Li, G.J. Mathews, R.
Moradi, M. Muccino, G.B. Pisani, F. Rastegarnia, J.A. Rueda, N. Sahakyan,
Y. Wang, S.-S. Xue, on behalf of the ICRA, ICRANet-INAF team, report:

GRB 220527A is observed by AGILE (Ursi et al. 2022, GCN 32129), Fermi (GCN
32130, Bissaldi et al. 2022, GCN 32131, Mangan et al. 2022, GCN 32133),
Swift (B. Sbarufatti et al. 2022 GCN 32135, A. Tohuvavohu. 2022, GCN
32136), CALET (Yamaoka et al. 2022, GCN 32139), AstroSat (Gopalakrishnan et
al. 2022, GCN 32140), and Konus-Wind (Lysenko et al. 2022, GCN 32152).

With the redshift z = 0.857 of GRB 220527A (D. Xu et al. 2022, GCN 32141),
the isotropic energy of this GRB in 10 keV - 10 MeV, and 20 keV - 16 MeV
ranges are E_iso=(2.60 +\- 0.14)x10^{53} erg, and
E_iso=1.22(-0.06,+0.07)x10^{53} erg, respectively (A. Lysenko et al. 2022,
GCN 32152).

The ultra-relativistic prompt emission phase of this GRB, originating from
the over-criticl electric field around the black hole (Moradi et al 2021,
Phys. Rev. D 104, 063043) extends from rest-frame time of 3.7s to 5.4s. The
UPE phase is best fitted by a cutoff power-law plus blackbody spectrum
(CPL+BB) with best fit parameters of: alpha = -0.57, Ep = 109.5 keV, beta =
-2.36, kT = 47.8 keV.

In addition to the above observations, the following observation of the GeV
emission (E. Bissaldi et al. 2022, GCN 32131), originated from the newborn
black hole (R. Ruffini et al. 2019 ApJ 886 82) and the afterglow emission
(B. Sbarufatti et al. 2022 GCN 32135, A. Tohuvavohu. 2022, GCN 32136)
originated from the newborn neutron star (J.A. Rueda et al. 2020 ApJ 893
148), confirm this GRB is a BDHN I.

Following Ruffini et al. 2021 (MNRAS, 504, 5301,doi:10.1093/mnras/stab724),
we predict the emergence of an optical supernova peak to be detected at
(25.1+/-3.5) days after the trigger (June 21th 2022, uncertainty from June
18th 2022 to June 24th 2022), with the bolometric optical luminosity of
L_SN,b=(9.0+/-2.7)x10^{42} erg/s.

Follow-up optical observations for the SN peak are encouraged.