Stellar black hole binary mergers in open clusters

ABSTRACT Black hole (BH) binary mergers formed through dynamical interactions in dense star clusters are believed to be one of the main sources of gravitational waves (GWs) for Advanced LIGO and Virgo. Here, we present a fast numerical method for simulating the evolution of star clusters with BHs, including a model for the dynamical formation and merger of BH binaries. Our method is based on Hénon’s principle of balanced evolution, according to which the flow of energy within a cluster must be balanced by the energy production inside its core. Because the heat production in the core is powered by the BHs, one can then link the evolution of the cluster to the evolution of its BH population. This allows us to construct evolutionary tracks of the cluster properties including its BH population and its effect on the cluster and, at the same time, determine the merger rate of BH binaries as well as their eccentricity distributions. The model is publicly available and includes the effects of a BH mass spectrum, mass-loss due to stellar evolution, the ejection of BHs due to natal and dynamical kicks, and relativistic corrections during binary–single encounters. We validate our method using direct N-body simulations, and find it to be in excellent agreement with results from recent Monte Carlo models of globular clusters. This establishes our new method as a robust tool for the study of BH dynamics in star clusters and the modelling of GW sources produced in these systems. Finally, we compute the rate and eccentricity distributions of merging BH binaries for a wide range of cluster initial conditions, spanning more than two orders of magnitude in mass and radius.

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Spectroscopy of candidate electromagnetic counterparts to gravitational wave sources

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316012515 ◽

2016 ◽

Vol 12 (S324) ◽

pp. 283-286

Author(s):

Iain A. Steele ◽

Chris M. Copperwheat ◽

Andrzej S. Piascik

Keyword(s):

Black Hole ◽

Gravitational Wave ◽

Wide Field ◽

Solar System Objects ◽

Multi Wavelength ◽

Binary Mergers ◽

Black Hole Binary ◽

Field Imaging ◽

Wide Field Imaging

AbstractA programme of worldwide, multi-wavelength electromagnetic follow-up of sources detected by gravitational wave detectors is in place. Following the discovery of GW150914 and GW151226, wide field imaging of their sky localisations identified a number of candidate optical counterparts which were then spectrally classified. The majority of candidates were found to be supernovae at redshift ranges similar to the GW events and were thereby ruled out as a genuine counterpart. Other candidates ruled out include AGN and Solar System objects. Given the GW sources were black hole binary mergers, the lack of an identified electromagnetic counterpart is not surprising. However the observations show that it is possible to organise and execute a campaign that can eliminate the majority of potential counterparts. Finally we note the existence of a “classification gap” with a significant fraction of candidates going unclassified.

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Prospects of probing dark energy with eLISA: Standard versus null diagnostics

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3346 ◽

2020 ◽

Vol 500 (3) ◽

pp. 2896-2907

Author(s):

Pratyusava Baral ◽

Soumendra Kishore Roy ◽

Supratik Pal

Keyword(s):

Black Hole ◽

Dark Energy ◽

Cosmological Parameters ◽

Supermassive Black Hole ◽

Wide Range ◽

Binary Mergers ◽

Model Independent ◽

Black Hole Binary ◽

Intermediate Redshift ◽

Shed Light

ABSTRACT Gravitational waves from supermassive black hole binary mergers along with an electromagnetic counterpart have the potential to shed ‘light’ on the nature of dark energy in the intermediate redshift regime. Accurate measurement of dark energy parameters at intermediate redshift is extremely essential to improve our understanding of dark energy, and to possibly resolve a couple of tensions involving cosmological parameters. We present a Fisher matrix forecast analysis in the context of eLISA to predict the errors for three different cases: the non-interacting dark energy with constant and evolving equation of state (EoS), and the interacting dark sectors with a generalized parametrization. In all three cases, we perform the analysis for two separate formalisms, namely, the standard EoS formalism and the Om parametrization which is a model-independent null diagnostic for a wide range of fiducial values in both phantom and non-phantom regions, to make a comparative analysis between the prospects of these two diagnostics in eLISA. Our analysis reveals that it is wiser and more effective to probe the null diagnostic instead of the standard EoS parameters for any possible signature of dark energy at intermediate redshift measurements like eLISA.

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