Stellar black hole binary mergers in open clusters

Rastello, Sara; Amaro-Seoane, Pau; Sedda, Manuel Arca; Capuzzo-Dolcetta, Roberto; Fragione, Giacomo; Melo, I. Tosta e

doi:10.1093/mnras/sty3193

Cited by 68 publications

(46 citation statements)

References 91 publications

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“…2) x 10 -9 yr -1 , compatible with the value expected for TDEs triggered by BH binaries 41,42 . The 90% of disrupted stars have a mass < 0.5 M☉, thus possibly representing white dwarfs or low-mass main sequence stars.…”

Section: Resultssupporting

confidence: 83%

Dissecting the properties of neutron star–black hole mergers originating in dense star clusters

Sedda

2020

Commun Phys

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The detection of gravitational waves emitted during a neutron star -black hole merger and the associated electromagnetic counterpart will provide a wealth of information about stellar evolution nuclear matter, and General Relativity. While the theoretical framework about neutron star -black hole binaries formed in isolation is well established, the picture is loosely constrained for those forming via dynamical interactions. Here, we use N-body simulations to show that mergers forming in globular and nuclear clusters could display distinctive marks compared to isolated mergers, namely larger masses, heavier black holes, and the tendency to have no associated electromagnetic counterpart. These features could represent a useful tool to interpreting forthcoming observations. In the Local Universe, gravitational waves emitted from dynamical mergers could be unravelled by detectors sensitive in the decihertz frequency band, while those occurring at the distance range of Andromeda and the Virgo Cluster could be accessible to lower-frequency detectors like LISA.The third observational campaign, O3, operated by the LIGO-Virgo Collaboration (LVC) will enlarge the family of gravitational wave (GW) sources, currently comprised of 11 confirmed black hole (BH) binary and 1 neutron star (NS) binary mergers 1 . The loot of observations accumulated during O3 will hopefully include the first BH binary with component masses in the so-called upper mass-gap, i.e. 50 − 150 M☉, and the first NS-BH merger. In fact, as reported in the gravitational-wave candidate event database (GraceDB, https://gracedb.ligo.org/), both events might have been already recorded. The observation of an NS-BH merger represents a crucial cornerstone in both GW astronomy and stellar evolution and dynamics. The GW signal emitted by this type of sources encodes information about the mass ratio of the binary, the BH spin, the NS compactness and equation of state 2-4 . The next generation of GW detectors will allow us to chase these objects up to the dawn of Universe 5 , offering us the unique chance to follow them from the inspiraling phase to the merger. The formation of an accretion disc during the merger could trigger a kilonova event 6 and power a short Gamma-ray burst (sGRB) 7 , making NS-BH mergers promising multimessenger sources. The coincident observation of GWs and a kilonova 8 , the detection of peculiar precession in the jets produced during the sGRB 9 , or the anisotropic emission of ejected matter 10 are some of the proposed signatures of a putative NS-BH electromagnetic (EM) counterpart. The properties of the EM emission depend on the binary properties close to the merger. A high eccentricity, for instance, can affect the amount of mass ejected, the mass accreted onto the BH and the angular momentum transferred 11 . The actual development of an EM counterpart is expected to depend likely on the mass ratio, the BH spin, and the NS equation of state 2-4,10-12 . For mass ratios smaller than ≃1/3 − 1/4, the NS undergoes tidal disruption inside the BH's ...

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Section: Resultssupporting

confidence: 83%

Dissecting the properties of neutron star–black hole mergers originating in dense star clusters

Sedda

2020

Commun Phys

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“…One of the critical parameters affecting the natal mass of BHs is the metallicity of their progenitors, Z, as metal-poor stars are expected to produce heavier BHs (Mapelli et al 2009(Mapelli et al , 2010Belczynski et al 2010;Mapelli & Bressan 2013;Spera et al 2015) and to have a higher merger efficiency than metal-rich stars (Dominik et al 2013;Askar et al 2017;Giacobbo et al 2018). Merging BBHs form either from isolated binary stellar evolution in galactic fields (Tutukov & Yungelson 1973;Portegies Zwart & McMillan 2000;Belczynski et al 2002Belczynski et al , 2010Belczynski et al , 2016aHurley et al 2002;Mapelli & Bressan 2013;Marchant et al 2016;Giacobbo et al 2018;Arca Sedda & Benacquista 2019;Spera et al 2019, and references therein), or through dynamical interactions in dense young massive clusters (Portegies Zwart & McMillan 2000;Banerjee et al 2010;Ziosi et al 2014;Mapelli 2016;Banerjee 2017Banerjee , 2018di Carlo et al 2019a;Rastello et al 2019), globular clusters (Sigurdsson & Phinney 1993;Lee 1995;Miller & Hamilton 2002;Wen 2003;O'Leary et al 2009;Downing et al 2010;Rodriguez et al 2015;Rodriguez et al 2016;Askar et al 2017;Hong et al 2018;…”

Section: Introductionmentioning

confidence: 99%

“…In star clusters, instead, the zoology of BBH mergers is quite vast. Dynamical scatterings can drive the shrinkage of a BBH down to a point where GWs dominate the evolution (Arca Samsing 2018;Zevin et al 2019), or can trigger the formation of triples that can efficiently affect the BBH end phase for both stable (Antonini et al 2017;Rastello et al 2019) or unstable systems (Arca .…”

Section: Introductionmentioning

confidence: 99%

Fingerprints of Binary Black Hole Formation Channels Encoded in the Mass and Spin of Merger Remnants

Sedda¹,

Mapelli

Spera

et al. 2020

ApJ

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Binary black holes (BBHs) are thought to form in different environments, including the galactic field and (globular, nuclear, young, and open) star clusters. Here, we propose a method to estimate the fingerprints of the main BBH formation channels associated with these different environments. We show that the metallicity distribution of galaxies in the local universe along with the relative amount of mergers forming in the field or in star clusters determine the main properties of the BBH population. Our fiducial model predicts that the heaviest merger to date, GW170729, originated from a progenitor that underwent 2-3 merger events in a dense star cluster, possibly a galactic nucleus. The model predicts that at least one merger remnant out of a hundred BBH mergers in the local universe has mass <  M M 90 110 rem  , and one in a thousand can reach a mass as large as  M M 250 rem . Such massive black holes would bridge the gap between stellar-mass and intermediate-mass black holes. The relative number of low-and high-mass BBHs can help us unravel the fingerprints of different formation channels. Based on the assumptions of our model, we expect that isolated binaries are the main channel of BBH merger formation if~70% of the whole BBH population has remnants with masses < M 50  , whereas 6% of remnants having masses > M 75  points to a significant subpopulation of dynamically formed BBH binaries.

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“…Several recent studies have examined the potential population of, in particular, dynamically-formed binaries in the LISA band. In [44][45][46], post-Newtonian (PN) direct N -body simulations were used to explore the population of LISA sources assembled dynamically in open clusters. [47] used Monte Carlo GC models (without PN corrections) to show that up to dozens of LISA sources may be found in the Milky Way GCs (including BBHs as well as other compact binaries containing neutron stars and white dwarfs).…”

Section: Introductionmentioning

confidence: 99%

Post-Newtonian dynamics in dense star clusters: Binary black holes in the LISA band

et al. 2019

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The dynamical processing of black holes in the dense cores of globular clusters (GCs), makes them efficient factories for producing binary black holes (BBHs). Here we explore the population of BBHs that form dynamically in GCs and may be observable at mHz frequencies or higher with the future space-based gravitational-wave observatory, LISA. We use our Monte Carlo stellar dynamics code, which includes gravitational radiation reaction effects for all BH encounters. By creating a representative local universe of GCs, we show that up to dozens of these systems may be resolvable by LISA. Approximately one third of these binaries will have measurable eccentricities (e > 10 −3 ) in the LISA band and a small number ( 5) may evolve from the LISA band to the LIGO band during the LISA mission.

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Stellar black hole binary mergers in open clusters

Cited by 68 publications

References 91 publications

Dissecting the properties of neutron star–black hole mergers originating in dense star clusters

Dissecting the properties of neutron star–black hole mergers originating in dense star clusters

Fingerprints of Binary Black Hole Formation Channels Encoded in the Mass and Spin of Merger Remnants

Post-Newtonian dynamics in dense star clusters: Binary black holes in the LISA band

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