Difference: GCNCIRCULAR21621 ( vs. 1)

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

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-- ShaonGhosh - 20 Aug 2017