Sixteenth Marcel Grossmann Meeting

Using fast ejecta to distinguish neutron stars from black holes in gravitational wave events in the lower mass gap

9 Jul 2021, 08:35

25m

Talk in the parallel session Explosive events associated with compact-object binary mergers Explosive Events Associated with Compact-Object Binary Mergers

Speaker

Elias Roland Most (Princeton University)

Description

Gravitational wave events involving very massive neutron stars, such as
GW190425, have just started to be detected. Although typically classified as
binary neutron star mergers, the observed gravitational-wave signal is
usually not able to clearly establish a neutron-star nature of the massive
primary object in the system. Thus, a black hole--neutron star system cannot
be fully ruled out by the gravitational wave detection alone.
In this talk, I will show how early fast ejecta -- only produced in binary
neutron star mergers -- can potentially resolve this question and shed light
on the nature of the binary system. By comparing simulations of binary
neutron
star and black hole -- neutron star mergers of exactly the same masses and
spins, I will show that such fast ejecta are entirely absent, if the primary
is a black hole. Because our simulations indicate that the
mass ejecta and accretion disks produced in the merger are comparable in
both cases, the presence of fast ejecta might be the only distinguishing
feature present in the electromagnetic afterglow accompanying such a
gravitational wave event.