Black hole–neutron star mergers in globular clusters

Clausen, Drew; Sigurd̵sson, Steinn; Chernoff, David F.

doi:10.1093/mnras/sts295

Cited by 80 publications

(69 citation statements)

References 75 publications

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“…Even considering the uncertainties in our measurements of M ej and hvi ej , this is clearly larger than the kick velocity due to gravitational wave emission (see Table III): our simulations predict v kick;ej ∼ 150 km= s-800 km=s but v kick;GW ∼ 20 km=s-100 km=s. These velocities play an important role when assessing whether globular clusters can retain a black hole after it merges with a neutron star, and in the determination of the rate of NSBH mergers occurring in those clusters [59]. At the high end of this velocity range, the kick could even be above the escape velocity of small galaxies.…”

Section: B Properties Of the Outflowsmentioning

confidence: 99%

Neutron star-black hole mergers with a nuclear equation of state and neutrino cooling: Dependence in the binary parameters

et al. 2014

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We present a first exploration of the results of neutron star-black hole mergers using black hole masses in the most likely range of 7M ⊙ -10M ⊙ , a neutrino leakage scheme, and a modeling of the neutron star material through a finite-temperature nuclear-theory based equation of state. In the range of black hole spins in which the neutron star is tidally disrupted (χ BH ≳ 0.7), we show that the merger consistently produces large amounts of cool (T ≲ 1 MeV), unbound, neutron-rich material (M ej ∼ 0.05M ⊙ -0.20M ⊙ ). A comparable amount of bound matter is initially divided between a hot disk (T max ∼ 15 MeV) with typical neutrino luminosity of L ν ∼ 10 53 erg=s, and a cooler tidal tail. After a short period of rapid protonization of the disk lasting ∼10 ms, the accretion disk cools down under the combined effects of the fall-back of cool material from the tail, continued accretion of the hottest material onto the black hole, and neutrino emission. As the temperature decreases, the disk progressively becomes more neutron rich, with dimmer neutrino emission. This cooling process should stop once the viscous heating in the disk (not included in our simulations) balances the cooling. These mergers of neutron star-black hole binaries with black hole masses of M BH ∼ 7M ⊙ -10M ⊙ , and black hole spins high enough for the neutron star to disrupt provide promising candidates for the production of short gamma-ray bursts, of bright infrared postmerger signals due to the radioactive decay of unbound material, and of large amounts of r-process nuclei.

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Section: B Properties Of the Outflowsmentioning

confidence: 99%

Neutron star-black hole mergers with a nuclear equation of state and neutrino cooling: Dependence in the binary parameters

et al. 2014

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“…We are aware of only one past study that attempted to estimate the NS-BH merger rate from GCs: Clausen et al (2013) followed the evolution of NS-BH binaries undergoing binary-single stellar interactions in static background cluster models. Compared to the current LIGO/Virgo merger rate upper limit (610 Gpc −3 yr −1 ) for NS-BHs, their estimated merger rate from GCs (0.01-0.17 Gpc −3 yr −1 ) appears negligible.…”

Section: Introductionmentioning

confidence: 99%

On the Rate of Neutron Star Binary Mergers from Globular Clusters

Fong

Kremer

et al. 2019

ApJL

182

134

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The first detection of gravitational waves from a neutron star -neutron star (NS-NS) merger, GW170817, and the increasing number of observations of short gamma-ray bursts (SGRBs) have greatly motivated studies of the origins of NS-NS and neutron star -black hole (NS-BH) binaries. We calculate the merger rates of NS-NS and NS-BH binaries from globular clusters (GCs) using realistic GC simulations with the CMC cluster catalog. We use a large sample of models with a range of initial numbers of stars, metallicities, virial radii and galactocentric distances, representative of the present-day Milky Way GCs, to quantify the inspiral times and volumetric merger rates as a function of redshift, both inside and ejected from clusters. We find that over the complete lifetime of most GCs, stellar BHs dominate the cluster cores and prevent the mass segregation of NSs, thereby reducing the dynamical interaction rates of NSs so that at most a few NS binary mergers are ever produced. We estimate the merger rate in the local universe to be ∼ 0.02 Gpc −3 yr −1 for both NS-NS and NS-BH binaries, or a total of ∼ 0.04 Gpc −3 yr −1 for both populations. These rates are about 5 orders of magnitude below the current empirical merger rate from LIGO/Virgo. We conclude that dynamical interactions in GCs do not play a significant role in enhancing the NS-NS and NS-BH merger rates.

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“…In this study we focus on the binary formation channels (in contrast to the dynamical formation channels that may occur in dense star clusters( e.g., Ivanova et al 2008;Banerjee et al 2010;Aarseth 2012;Clausen et al 2013;Samsing et al 2014;Ramirez-Ruiz et al 2015). We investigate two questions: (i) What are the implications of the new initial conditions?…”

Section: Introductionmentioning

confidence: 99%

Merger Rates of Double Neutron Stars and Stellar Origin Black Holes: The Impact of Initial Conditions on Binary Evolution Predictions

Mink

Belczyński

2015

ApJ

202

151

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The initial mass function (IMF), binary fraction, and distributions of binary parameters (mass ratios, separations, and eccentricities) are indispensable inputs for simulations of stellar populations. It is often claimed that these are poorly constrained, significantly affecting evolutionary predictions. Recently, dedicated observing campaigns have provided new constraints on the initial conditions for massive stars. Findings include a larger close binary fraction and a stronger preference for very tight systems. We investigate the impact on the predicted merger rates of neutron stars and black holes. Despite the changes with previous assumptions, we only find an increase of less than a factor of 2 (insignificant compared with evolutionary uncertainties of typically a factor of 10-100). We further show that the uncertainties in the new initial binary properties do not significantly affect (within a factor of 2) our predictions of double compact object merger rates. An exception is the uncertainty in IMF (variations by a factor of 6 up and down). No significant changes in the distributions of final component masses, mass ratios, chirp masses, and delay times are found. We conclude that the predictions are, for practical purposes, robust against uncertainties in the initial conditions concerning binary parameters, with the exception of the IMF. This eliminates an important layer of the many uncertain assumptions affecting the predictions of merger detection rates with the gravitational wave detectors aLIGO/aVirgo.

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Black hole–neutron star mergers in globular clusters

Cited by 80 publications

References 75 publications

Neutron star-black hole mergers with a nuclear equation of state and neutrino cooling: Dependence in the binary parameters

Neutron star-black hole mergers with a nuclear equation of state and neutrino cooling: Dependence in the binary parameters

On the Rate of Neutron Star Binary Mergers from Globular Clusters

Merger Rates of Double Neutron Stars and Stellar Origin Black Holes: The Impact of Initial Conditions on Binary Evolution Predictions

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