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Abstract

(Abridged) While the gravitational-wave (GW) signal GW170817 was accompanied
by a variety of electromagnetic (EM) counterparts, sufficiently high-mass
binary neutron star (BNS) mergers are expected to be unable to power bright EM
counterparts. The putative high-mass binary BNS merger GW190425, for which no
confirmed EM counterpart has been identified, may be an example of such a
system. It is thus important to understand how well we will be able to
distinguish high-mass BNSs and low-mass binary black holes (BBHs) solely from
their GW signals. To do this, we consider the imprint of the tidal
deformability of the neutron stars on the GW signal for systems undergoing
prompt black hole formation after merger. We model the BNS signals using hybrid
numerical relativity -- tidal effective-one-body waveforms. Specifically, we
consider a set of five nonspinning equal-mass BNS signals with masses of 2.7,
3.0, 3.2 Msun and with three different equations of state, as well as the
analogous BBH signals. We perform parameter estimation on these signals in
three networks: Advanced LIGO-Advanced Virgo and Advanced LIGO-Advanced
Virgo-KAGRA with sensitivities similar to O3 and O4, respectively, and a 3G
network of two Cosmic Explorers (CEs) and one Einstein Telescope, with a CE
sensitivity similar to Stage 2. Our analysis suggests that we cannot
distinguish the signals from high-mass BNSs and BBHs at a 90% credible level
with the O3-like network even at 40 Mpc. However, we can distinguish all but
the most compact BNSs that we consider in our study from BBHs at 40 Mpc at a >=
95% credible level using the O4-like network, and can even distinguish them at
a > 99.2% (>= 97%) credible level at 369 (835) Mpc using the 3G network.
Additionally, we present a simple method to compute the leading effect of the
Earth's rotation on the response of a gravitational wave detector in the
frequency domain.