LIGO Document P1600171-v11

Upper limits on the rates of binary neutron star and black-hole–neutron-star mergers from Advanced LIGO’s first observing run

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We report here the non-detection of gravitational waves from the merger of binary neutron star
systems and neutron-star–black-hole systems during the first observing run of Advanced LIGO.
In particular we searched for gravitational wave signals from binary neutron star systems with
component masses ∈ [1,3]M⊙ and component dimensionless spins 0.05. We also searched for
neutron-star–black-hole systems with the same neutron star parameters, black hole mass ∈ [2, 99]M⊙
and no restriction on the black hole spin magnitude. We calculate the sensitivity of the two LIGO
detectors to these systems, and find that they could have detected the merger of binary neutron star
systems with component mass distributions of 1.35 ± 0.13M⊙ at an average distance of ∼ 70 Mpc,
and for neutron-star–black-hole systems with neutron star masses of 1.4M⊙ and black hole masses of
at least 5M⊙, an average distance of at least ∼ 110 Mpc. From this we constrain with 90% confidence
the merger rate to be less than 12,600 Gpc−3 yr−1 for binary-neutron star systems and less than
3,600 Gpc−3 yr−1 for neutron-star–black-hole systems. We discuss the astrophysical implications
of these results, which we find to be in tension with only the most optimistic predictions. However,
we find that if no detection of neutron-star binary mergers is made in the next two Advanced LIGO
and Advanced Virgo observing runs we would place meaningful constraints on the merger rates.
Finally, assuming a short gamma ray burst rate of 10+20Gpc−3 yr−1 and assuming that all short
gamma-ray bursts have binary-neutron-star (neutron-star–black-hole) progenitors we can use our
90% confidence rate upper limits to constrain the beaming angle of the gamma-ray burst to be
greater than 2.3+1.7 ◦ (4.3+3.1 ◦ ). −1.1 −1.9
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