[vsnet-grb-info 27713] GRB 210410A: A twin of short GRB 090510 with complementary observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29816
SUBJECT: GRB 210410A: A twin of short GRB 090510 with complementary observations
DATE:    21/04/15 08:43:33 GMT
FROM:    Remo Rufinni at ICRA  <ruffini at icra.it>

 Y. Aimuratov, C.L. Bianco, L. 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:

GRB 210410A has been announced as a likely long GRB (Fermi GBM Team
2021, GCN 29777), it has been also observed by Swift-XRT (A. Melandri
et al 2021, GCN 29778, and A. D’Ai et al, 2021, GCN 29790), by
Fermi-LAT (M. Arimoto et al 2021, GCN 29781), by AGILE (A. Ursi et al.
2021, GCN 29782), by Swift BAT (A. Y. Lien et al, 2021 GCN 29793) as
well as by Konus-Wind (A. Ridnaia et al 2021, GCN 29797). The
Fermi-GBM has determined T90=48 s in 50-300 keV (J. Wood et al 2021,
GCN 29788). A possible detection of the host galaxy at redshift z<3.6
was indicated by Butler et al 2021 (GCN 29784).

We here propose that GRB 210410A is a twin and covers the
complementary observation to the short GRB 090510, with T90=0.3 s. (R.
Ruffini et al 2016 ApJ 831 178).

We infer that GRB 210410A is a short GRB originating from a black hole
formation in view of its observed GeV emission (M. Arimoto et al
GCN29781) that and no supernova will be detected. We evidence for the
first time an angle dependence of the emission of short GRB: in the
polar observation for GRB 090510, with T90=0.3 s and in the equatorial
observation for GRB 210410A, with T90=48 s.

The spectroscopic determination of the redshift of the host galaxy is
essential for the determination of the GeV luminosity and consequently
the BH mass (R. Ruffini et al 2019 ApJ 886 82). We indicate the
relevance of the redshift determinations in the two enclosed figures.

"http://www.icranet.org/documents/GRB210410A-z=0.6-and-GRB090510-z=0.903.pdf"

"http://www.icranet.org/documents/GRB210410A-z=3.6-and-GRB090510-z=0.903.pdf"