scholarly journals Implications of Eccentric Observations on Binary Black Hole Formation Channels

2021 ◽  
Vol 921 (2) ◽  
pp. L43
Author(s):  
Michael Zevin ◽  
Isobel M. Romero-Shaw ◽  
Kyle Kremer ◽  
Eric Thrane ◽  
Paul D. Lasky
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
State Of The Art ◽  
Star Clusters ◽  
Selection Effects ◽  
Orbital Eccentricity ◽  
Hole Formation ◽  
Local Universe ◽  
Binary Black Holes ◽  
Binary Black Hole

Abstract Orbital eccentricity is one of the most robust discriminators for distinguishing between dynamical and isolated formation scenarios of binary black hole mergers using gravitational-wave observatories such as LIGO and Virgo. Using state-of-the-art cluster models, we show how selection effects impact the detectable distribution of eccentric mergers from clusters. We show that the observation (or lack thereof) of eccentric binary black hole mergers can significantly constrain the fraction of detectable systems that originate from dynamical environments, such as dense star clusters. After roughly 150 observations, observing no eccentric binary signals would indicate that clusters cannot make up the majority of the merging binary black hole population in the local universe (95% credibility). However, if dense star clusters dominate the rate of eccentric mergers and a single system is confirmed to be measurably eccentric in the first and second gravitational-wave transient catalogs, clusters must account for at least 14% of detectable binary black hole mergers. The constraints on the fraction of detectable systems from dense star clusters become significantly tighter as the number of eccentric observations grows and will be constrained to within 0.5 dex once 10 eccentric binary black holes are observed.

scholarly journals Constrains on the electric charges of the binary black holes with GWTC-1 events

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
Hai-Tang Wang ◽  
Peng-Cheng Li ◽  
Jin-Liang Jiang ◽  
Guan-Wen Yuan ◽  
Yi-Ming Hu ◽  
...  
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
Electric Charge ◽  
Modified Gravity ◽  
Fisher Information Matrix ◽  
Information Matrix ◽  
Charge Effect ◽  
Leading Order ◽  
Binary Black Holes ◽  
Binary Black Hole

AbstractTesting black hole’s charged property is a fascinating topic in modified gravity and black hole astrophysics. In the first Gravitational-Wave Transient Catalog (GWTC-1), ten binary black hole merger events have been formally reported, and these gravitational wave signals have significantly enhanced our understanding of the black hole. In this paper, we try to constrain the amount of electric charge with the parameterized post-Einsteinian framework by treating the electric charge as a small perturbation in a Bayesian way. We find that the current limits in our work are consistent with the result of Fisher information matrix method in previous works. We also develop a waveform model considering a leading order charge effect for binary black hole inspiral.

scholarly journals The Eccentric and Accelerating Stellar Binary Black Hole Mergers in Galactic Nuclei: Observing in Ground and Space Gravitational-wave Observatories

2021 ◽  
Vol 923 (2) ◽  
pp. 139
Author(s):  
Fupeng Zhang ◽  
Xian Chen ◽  
Lijing Shao ◽  
Kohei Inayoshi
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
Signal To Noise Ratio ◽  
Galactic Nuclei ◽  
Signal To Noise ◽  
High Eccentricity ◽  
Massive Black Hole ◽  
Binary Black Holes ◽  
Binary Black Hole ◽  
Space Observatories

Abstract We study the stellar binary black holes (BBHs) inspiraling/merging in galactic nuclei based on our numerical method GNC. We find that 3%–40% of all newborn BBHs will finally merge due to various dynamical effects. In a five-year mission, up to 104, 105, and ∼100 of BBHs inspiraling/merging in galactic nuclei can be detected with signal-to-noise ration >8 in Advanced LIGO (aLIGO), Einstein/DECIGO, and TianQin/LISA/TaiJi, respectively. Roughly tens are detectable in both LISA/TaiJi/TianQin and aLIGO. These BBHs have two unique characteristics. (1) Significant eccentricities: 1%–3%, 2%–7%, or 30%–90% of them have e i > 0.1 when they enter into aLIGO, Einstein, or space observatories, respectively. Such high eccentricities provide a possible explanation for that of GW190521. Most highly eccentric BBHs are not detectable in LISA/Tianqin/TaiJi before entering into aLIGO/Einstein, as their strain becomes significant only at f GW ≳ 0.1 Hz. DECIGO becomes an ideal observatory to detect those events, as it can fully cover the rising phase. (2) Up to 2% of BBHs can inspiral/merge at distances ≲103 r SW from the massive black hole, with significant accelerations, such that the Doppler phase drift of ∼10–105 of them can be detected with signal-to-noise ratio >8 in space observatories. The energy density of the gravitational-wave backgrounds (GWBs) contributed by these BBHs deviates from the power-law slope of 2/3 at f GW ≲ 1 mHz. The high eccentricity, significant accelerations, and the different profile of the GWB of these sources make them distinguishable, and thus interesting for future gravitational-wave detections and tests of relativities.

scholarly journals Searching for eccentricity: signatures of dynamical formation in the first gravitational-wave transient catalogue of LIGO and Virgo

2019 ◽  
Vol 490 (4) ◽  
pp. 5210-5216 ◽  
Author(s):  
Isobel M Romero-Shaw ◽  
Paul D Lasky ◽  
Eric Thrane
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Bayesian Inference ◽  
Gravitational Wave ◽  
Globular Clusters ◽  
Reference Frequency ◽  
Binary Black Holes ◽  
Binary Black Hole ◽  
Upper Limits ◽  
Formation History

ABSTRACT Binary black holes are thought to form primarily via two channels: isolated evolution and dynamical formation. The component masses, spins, and eccentricity of a binary black hole system provide clues to its formation history. We focus on eccentricity, which can be a signature of dynamical formation. Employing the spin-aligned eccentric waveform model seobnre, we perform Bayesian inference to measure the eccentricity of binary black hole merger events in the first gravitational-wave transient catalogue of LIGO and Virgo. We find that all of these events are consistent with zero eccentricity. We set upper limits on eccentricity ranging from 0.02 to 0.05 with 90  per cent confidence at a reference frequency of $10\, {\rm Hz}$. These upper limits do not significantly constrain the fraction of LIGO–Virgo events formed dynamically in globular clusters, because only $\sim 5{{\ \rm per\ cent}}$ are expected to merge with measurable eccentricity. However, with the gravitational-wave transient catalogue set to expand dramatically over the coming months, it may soon be possible to significantly constrain the fraction of mergers taking place in globular clusters using eccentricity measurements.

scholarly journals New insights on binary black hole formation channels after GWTC-2: young star clusters versus isolated binaries

2021 ◽  
Author(s):  
Yann Bouffanais ◽  
Michela Mapelli ◽  
Filippo Santoliquido ◽  
Nicola Giacobbo ◽  
Ugo N Di Carlo ◽  
...  
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
Star Clusters ◽  
Credible Interval ◽  
Young Star ◽  
Compact Objects ◽  
Bayesian Hierarchical ◽  
Binary Black Hole ◽  
Higher Spin ◽  
Young Star Clusters

Abstract With the recent release of the second gravitational-wave transient catalogue (GWTC-2), which introduced dozens of new detections, we are at a turning point of gravitational wave astronomy, as we are now able to directly infer constraints on the astrophysical population of compact objects. Here, we tackle the burning issue of understanding the origin of binary black hole (BBH) mergers. To this effect, we make use of state-of-the-art population synthesis and N-body simulations, to represent two distinct formation channels: BBHs formed in the field (isolated channel) and in young star clusters (dynamical channel). We then use a Bayesian hierarchical approach to infer the distribution of the mixing fraction f, with f = 0 (f = 1) in the pure dynamical (isolated) channel. We explore the effects of additional hyper-parameters of the model, such as the spread in metallicity σZ and the parameter σsp, describing the distribution of spin magnitudes. We find that the dynamical model is slightly favoured with a median value of f = 0.26, when σsp = 0.1 and σZ = 0.4. Models with higher spin magnitudes tend to strongly favour dynamically formed BBHs (f ≤ 0.1 if σsp = 0.3). Furthermore, we show that hyper-parameters controlling the rates of the model, such as σZ, have a large impact on the inference of the mixing fraction, which rises from 0.18 to 0.43 when we increase σZ from 0.2 to 0.6, for a fixed value of σsp = 0.1. Finally, our current set of observations is better described by a combination of both formation channels, as a pure dynamical scenario is excluded at the $99{{\ \rm per\ cent}}$ credible interval, except when the spin magnitude is high.

scholarly journals Implications of recoil kicks for black hole mergers from LIGO/Virgo catalogs

2021 ◽  
Vol 502 (3) ◽  
pp. 3879-3884
Author(s):  
Giacomo Fragione ◽  
Abraham Loeb
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
Globular Clusters ◽  
Star Clusters ◽  
Star Cluster ◽  
Effective Spin ◽  
The Third ◽  
Binary Black Hole ◽  
Super Star Clusters ◽  
Escape Speed

ABSTRACT The first and second Gravitational Wave Transient Catalogs by the LIGO/Virgo Collaboration include 50 confirmed merger events from the first, second, and first half of the third observational runs. We compute the distribution of recoil kicks imparted to the merger remnants and estimate their retention probability within various astrophysical environments as a function of the maximum progenitor spin (χmax), assuming that the LIGO/Virgo binary black hole (BBH) mergers were catalyzed by dynamical assembly in a dense star cluster. We find that the distributions of average recoil kicks are peaked at about $150\, \rm km\, s^{-1}$, $250\, \rm km\, s^{-1}$, $350\, \rm km\, s^{-1}$, $600\, \rm km\, s^{-1}$, for maximum progenitor spins of 0.1, 0.3, 0.5, 0.8, respectively. Only environments with escape speed ${\gtrsim}100\, \rm km\, s^{-1}$, as found in galactic nuclear star clusters as well as in the most massive globular clusters and super star clusters, could efficiently retain the merger remnants of the LIGO/Virgo BBH population even for low progenitor spins (χmax = 0.1). In the case of high progenitor spins (χmax ≳ 0.5), only the most massive nuclear star clusters can retain the merger products. We also show that the estimated values of the effective spin and of the remnant spin of GW170729, GW190412, GW190519_153544, and GW190620_030421 can be reproduced if their progenitors were moderately spinning (χmax ≳ 0.3), while for GW190517_055101 if the progenitors were rapidly spinning (χmax ≳ 0.8). Alternatively, some of these events could be explained if at least one of the progenitors is already a second-generation BH, originated from a previous merger.

scholarly journals Characterizing the Observation Bias in Gravitational-wave Detections and Finding Structured Population Properties

2021 ◽  
Vol 922 (2) ◽  
pp. 258
Author(s):  
Doğa Veske ◽  
Imre Bartos ◽  
Zsuzsa Márka ◽  
Szabolcs Márka
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
Computational Cost ◽  
Data Sets ◽  
Selection Effects ◽  
Analytical Formulation ◽  
Structured Population ◽  
Binary Black Hole ◽  
Observation Bias ◽  
Two Peaks

Abstract The observed distributions of the source properties from gravitational-wave (GW) detections are biased due to the selection effects and detection criteria in the detections, analogous to the Malmquist bias. In this work, this observation bias is investigated through its fundamental statistical and physical origins. An efficient semi-analytical formulation for its estimation is derived, which is as accurate as the standard method of numerical simulations, with only a millionth of the computational cost. Then, the estimated bias is used for unmodeled inferences on the binary black hole population. These inferences show additional structures, specifically two peaks in the joint mass distribution around binary masses ∼10 M ⊙ and ∼30 M ⊙. Example ready-to-use scripts and some produced data sets for this method are shared in an online repository.

scholarly journals Binary black hole mergers in AGN accretion discs: gravitational wave rate density estimates

2020 ◽  
Vol 638 ◽  
pp. A119 ◽  
Author(s):  
M. Gröbner ◽  
W. Ishibashi ◽  
S. Tiwari ◽  
M. Haney ◽  
P. Jetzer
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
Weighted Average ◽  
Accretion Disc ◽  
Accretion Discs ◽  
Binary Interaction ◽  
Orbital Eccentricity ◽  
Binary Black Hole ◽  
Binary Evolution ◽  
Merger Rate

The majority of gravitational wave (GW) events detected so far by LIGO/Virgo originate from binary black hole (BBH) mergers. Among the different binary evolution paths, the merger of BBHs in accretion discs of active galactic nuclei (AGNs) is a possible source of GW detections. We consider an idealised analytical model of the orbital evolution of BBHs embedded in an AGN accretion disc. In this framework, the disc–binary interaction increases the orbital eccentricity and decreases the orbital separation, driving the BBH into a regime where GW emission eventually leads to coalescence. We compute the resulting GW merger rate density from this channel based on a weighted average of the merger timescales of a population of BBHs radially distributed within the AGN accretion disc. The predicted merger rates broadly lie in the range ℛ ∼ (0.002−18) Gpc−3 yr−1. We analyse the dependence of the merger rate density on both the accretion disc and binary orbital parameters, emphasising the important role of the orbital eccentricity. We discuss the astrophysical implications of this particular BBH-in-AGN formation channel in the broader context of binary evolution scenarios.

scholarly journals Optimization of model independent gravitational wave search for binary black hole mergers using machine learning

2021 ◽  
Vol 104 (2) ◽  
Author(s):  
T. Mishra ◽  
B. O’Brien ◽  
V. Gayathri ◽  
M. Szczepańczyk ◽  
S. Bhaumik ◽  
...  
Keyword(s):  
Machine Learning ◽  
Black Hole ◽  
Gravitational Wave ◽  
Binary Black Hole ◽  
Model Independent

A Conversation among Young Astrophysicists

2021 ◽  
Vol 30 (6) ◽  
pp. 20-29
Author(s):  
Young-Min KIM ◽  
Miok PARK ◽  
Yeong-Bok BAE ◽  
Sungwook E HONG ◽  
Chan PARK
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
Daily Life ◽  
Physical Significance ◽  
Hole Formation ◽  
Formation Theory ◽  
Black Hole Formation ◽  
Supermassive Black Hole ◽  
Nobel Prizes

Recently, many Nobel Prizes in Physics have been awarded in the field of astrophysics. Gravitational wave observations and contributions to LIGO in 2017, cosmology and exoplanets in 2019, and black hole formation theory and discovery of a supermassive black hole in 2020. Surprisingly, that these topics, which are somewhat distant from our daily life, have great physical significance and are being actively studied worldwide. We invited young astrophysicists at the forefront of astrophysic research to share their thoughts on astrophysics. That conversation took place online on June 2, 2021.

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