Black Hole Mergers from an Evolving Population of Globular Clusters

Fragione, Giacomo; Kocsis, Bence

doi:10.1103/physrevlett.121.161103

Cited by 199 publications

(140 citation statements)

References 64 publications

(100 reference statements)

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“…Indeed, Belczynski et al (2018) used zero natal kicks for ECSN NSs in their NS-NS merger rate calculations and estimated a merger rate of about 10 times higher than ours, but still not high enough to explain the empirical LIGO/Virgo NS-NS merger rate. Although we have limited this analysis to those globular clusters that survive to the present day, there may also exist a potentially significant number of additional massive clusters that disrupted at earlier times (e.g., Fragione & Kocsis 2018;Rodriguez & Loeb 2018;Krumholz et al 2019, and references therein). Depending on the disruption timescales, these clusters may in principle also contribute to the population of dynamically-formed NS-NS and NS-BH mergers.…”

Section: Discussion and Summarymentioning

confidence: 99%

On the Rate of Neutron Star Binary Mergers from Globular Clusters

Fong

Kremer

et al. 2019

ApJL

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178

135

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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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Section: Discussion and Summarymentioning

confidence: 99%

On the Rate of Neutron Star Binary Mergers from Globular Clusters

Fong

Kremer

et al. 2019

ApJL

Self Cite

178

135

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“…[18][19][20], hence they would produce binaries with values of the effective spin parameter compatibles with the observed ones. The observed merger rate is on the upper end of the predicted range for stellar progenitors [21] (even though there are still many uncertainties), and at least some contribution from primordial objects would reconcile theory with observations. Furthermore, PBHs might constitute the seeds of the super-massive black holes [22,23] that inhabit the center of galaxies [24][25][26][27].…”

Section: Introductionmentioning

confidence: 85%

From primordial black holes abundance to primordial curvature power spectrum (and back)

Kalaja

Bellomo

Bartolo

et al. 2019

J. Cosmol. Astropart. Phys.

103

105

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In the model where Primordial Black Holes (PBHs) form from large primordial curvature (C) perturbations, i.e., CPBHs, constraints on PBH abundance provide in principle constraints on the primordial curvature power spectrum. This connection however depends necessarily on the details of PBH formation mechanism. In this paper we provide, for the first time, constraints on the primordial curvature power spectrum from the latest limits on PBH abundance, taking into account all the steps from gravitational collapse in real space to PBH formation. In particular, we use results from numerical relativity simulations and peak theory to study the conditions for PBH formation for a range of perturbation shapes, including nonlinearities, perturbation profile and a careful treatment of smoothing and filtering scales. We then obtain updated PBH formation conditions and translate that into primordial spectrum constraints for a wide range of shapes and abundances. These updated constraints cover a range of scales not probed by other cosmological observables. Our results show that the correct and accurate modelling of non-linearities, filtering and typical perturbation profile, is crucial for deriving meaningful cosmological implications.

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“…Ten stellar black hole -black hole (BH-BH) detections of binary mergers have been announced to date by Advanced LIGO and Virgo, which implies a merger rate density of 24−112 yr −1 Gpc −3 in the Universe for a power law BH mass function prior (The LIGO Scientific Collaboration et al 2018a,b). Several astrophysical channels have been proposed to explain these rates including isolated binary evolution in the galactic field (Belczynski et al 2016) and dynamically formed binaries in globular clusters Fragione & Kocsis 2018). All these events are consistent with being approximately circular, which is expected if the binaries form with a sufficiently large periapsis, since gravitational wave (GW) emission circularizes the orbit as it shrinks (Peters 1964).…”

Section: Introductionmentioning

confidence: 90%

The Rate of Stellar Mass Black Hole Scattering in Galactic Nuclei

Rasskazov

Kocsis

2019

ApJ

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We consider a black hole (BH) density cusp in a nuclear star cluster (NSC) hosting a supermassive back hole (SMBH) at its center. Assuming the stars and BHs inside the SMBH sphere of influence are mass-segregated, we calculate the number of BHs that sink into this region under the influence of dynamical friction. We find that the total number of BHs increases significantly in this region due to this process for lower mass SMBHs by up to a factor of 5, but there is no increase in the vicinity of the highest mass SMBHs. Due to the high BH number density in the NSC, BH-BH binaries form during close approaches due to GW emission. We update the previous estimate of O'Leary et al. for the rate of such GW capture events by estimating the n 2 / n 2 parameter where n is the number density. We find a BH merger rate for this channel to be in the range ∼ 0.002 − 0.04 Gpc −3 yr −1 . The total merger rate is dominated by the smallest galaxies hosting SMBHs, and the number of heaviest BHs in the NSC. It is also exponentially sensitive to the radial number density profile exponent, reaching > 100 Gpc −3 yr −1 when the BH mass function is m −2.3 or shallower and the heaviest BH radial number density is close to r −3 . Even if the rate is much lower than the range constrained by the current LIGO detections, the GW captures around SMBHs can be distinguished by their high eccentricity in the LIGO band.

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Black Hole Mergers from an Evolving Population of Globular Clusters

Cited by 199 publications

References 64 publications

On the Rate of Neutron Star Binary Mergers from Globular Clusters

On the Rate of Neutron Star Binary Mergers from Globular Clusters

From primordial black holes abundance to primordial curvature power spectrum (and back)

The Rate of Stellar Mass Black Hole Scattering in Galactic Nuclei

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