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GCN Circular 21621

Subject
LIGO/Virgo G298048: On the kick velocity and age of the binary Neutron Stars Progenitor
Date
2017-08-20T15:40:35Z (7 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov2007@gmail.com>
V.M.Lipunov,
Lomonosov Moscow State University, Sternberg Astronomical Institute

There are several very important arguments  for reality SSS17a as 
the kilonova  candidate  was published in LVC GCN. There are relativictic 
expansion  (see Nichol etal., LVC GCN 21585;) and big distance 
(delta ~ 3.9Mpc) 
between host galaxy explositions   ( D'Elia et al.,  LVC GCN 21592).

I point out that we can obtain minimal radial space velosity of the 
progenitor of the G298048:

      V_min = delta/T_Universe = 3.9 Mpc / 13.7 10^10 yrs  ~ 300 km/sec.

From other hand, because kick velosity realy is not more than 1000 km/s, 
we received typical age of the binary NS's as several billion years.

This is not contadict to Scenario Machine population synthesis of the 
NS+NS star merging rates evolution in Universe (Lipunov et al., 
1995, Evolution of  the Double Neutron Star Merging Rate and the 
Cosmological Origin of Gamma-Ray Burst Sources,1995,
Astrophysical Journal v.454, p.593; Lipunov & 
Pruzhinskaya; MNRAS, Vol. 440,  1193-1199, 2014.

From the other hand diference between NGC 4993 galaxy redshift and 
Kilonova ( D'Elia et al.,  LVC GCN 21592) may be explained by fast moving 
relativistic shell where some absobtion lines can be formed.

The NS+NS merging rate evolution from Lipunov et al., 1995 is available at
http://master.sai.msu.ru/static/images/green_function.jpg


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