scholarly journals The spin of the second-born black hole in coalescing binary black holes

2018 ◽  
Vol 616 ◽  
pp. A28 ◽  
Author(s):  
Y. Qin ◽  
T. Fragos ◽  
G. Meynet ◽  
J. Andrews ◽  
M. Sørensen ◽  
...  

Context. Various binary black hole formation channels have been proposed since the first gravitational event GW150914 was discovered by the Advanced Laser Interferometer Gravitational-Wave Observatory (AdLIGO). The immediate progenitor of the binary black hole is a close binary system composed of a black hole and a helium star, which can be the outcome of the classical isolated binary evolution through the common envelope, or alternatively of the massive close evolution through chemically homogeneous channel. Aims. We study the spin angular momentum evolution of the helium star in order to constrain the spin of the second-born black hole. This work focuses on the common envelope formation channel, however, some of our conclusions are also relevant for the chemically homogeneous evolution channel. Methods. We perform detailed stellar structure and binary evolution calculations that take into account, mass-loss, internal differential rotation, and tidal interactions between the helium star and the black hole companion, where we also calculate the strength of the tidal interactions from first principles based on the structure of the helium stars. We systematically explore the parameter space of initial binary properties, including initial black hole and helium star masses, initial rotation of the helium star as well as metallicity. Results. We argue that the natal spin of the first-born black hole through the common envelope scenario is negligible (≲0.1), and therefore the second-born black hole’s spin dominates the measured effective spin, χeff, from gravitational wave events of double black hole mergers. We find that tides can be only important when orbital periods are shorter than 2 days. Upon core collapse, the helium star produces a black hole (the second-born black hole in the system) with a spin that can span the entire range from zero to maximally spinning. We show that the bimodal distribution of the spin of the second-born black hole obtained in recent papers is mainly due to oversimplifying assumptions. We find an anti-correlation between the merging timescale of the two black holes, Tmerger, and the effective spin χeff. Finally, we provide new prescriptions for the tidal coefficient E2 for both H-rich and the He-rich stars. Conclusions. To understand the spin of the second-born black hole, careful treatment of both tides and stellar winds is needed. We predict that, with future improvements to AdLIGO’s sensitivity, the sample of merging binary black hole systems will show an overdensity of sources with positive but small χeff originating from lower-mass black hole mergers born at low redshift.

2020 ◽  
Vol 635 ◽  
pp. A97 ◽  
Author(s):  
Simone S. Bavera ◽  
Tassos Fragos ◽  
Ying Qin ◽  
Emmanouil Zapartas ◽  
Coenraad J. Neijssel ◽  
...  

Context. After years of scientific progress, the origin of stellar binary black holes is still a great mystery. Several formation channels for merging black holes have been proposed in the literature. As more merger detections are expected with future gravitational-wave observations, population synthesis studies can help to distinguish between them. Aims. We study the formation of coalescing binary black holes via the evolution of isolated field binaries that go through the common envelope phase in order to obtain the combined distributions of observables such as black-hole spins, masses and cosmological redshifts of mergers. Methods. To achieve this aim, we used a hybrid technique that combines the parametric binary population synthesis code COMPAS with detailed binary evolution simulations performed with the MESA code. We then convolved our binary evolution calculations with the redshift- and metallicity-dependent star-formation rate and the selection effects of gravitational-wave detectors to obtain predictions of observable properties. Results. By assuming efficient angular momentum transport, we are able to present a model that is capable of simultaneously predicting the following three main gravitational-wave observables: the effective inspiral spin parameter χeff, the chirp mass Mchirp and the cosmological redshift of merger zmerger. We find an excellent agreement between our model and the ten events from the first two advanced detector observing runs. We make predictions for the third observing run O3 and for Advanced LIGO design sensitivity. We expect approximately 80% of events with χeff <  0.1, while the remaining 20% of events with χeff ≥ 0.1 are split into ∼10% with Mchirp <  15 M⊙ and ∼10% with Mchirp ≥ 15 M⊙. Moreover, we find that Mchirp and χeff distributions are very weakly dependent on the detector sensitivity. Conclusions. The favorable comparison of the existing LIGO/Virgo observations with our model predictions gives support to the idea that the majority, if not all of the observed mergers, originate from the evolution of isolated binaries. The first-born black hole has negligible spin because it lost its envelope after it expanded to become a giant star, while the spin of the second-born black hole is determined by the tidal spin up of its naked helium star progenitor by the first-born black hole companion after the binary finished the common-envelope phase.


2020 ◽  
Vol 498 (2) ◽  
pp. 1905-1910 ◽  
Author(s):  
Gregory Ashton ◽  
Eric Thrane

ABSTRACT The gravitational-wave candidate GW151216 is a proposed binary black hole event from the first observing run of the Advanced LIGO detectors. Not identified as a bona fide signal by the LIGO–Virgo collaboration, there is disagreement as to its authenticity, which is quantified by pastro, the probability that the event is astrophysical in origin. Previous estimates of pastro from different groups range from 0.18 to 0.71, making it unclear whether this event should be included in population analyses, which typically require pastro &gt; 0.5. Whether GW151216 is an astrophysical signal or not has implications for the population properties of stellar-mass black holes and hence the evolution of massive stars. Using the astrophysical odds, a Bayesian method that uses the signal coherence between detectors and a parametrized model of non-astrophysical detector noise, we find that pastro = 0.03, suggesting that GW151216 is unlikely to be a genuine signal. We also analyse GW150914 (the first gravitational-wave detection) and GW151012 (initially considered to be an ambiguous detection) and find pastro values of 1 and 0.997, respectively. We argue that the astrophysical odds presented here improve upon traditional methods for distinguishing signals from noise.


2021 ◽  
Vol 81 (7) ◽  
Author(s):  
Adrian Ka-Wai Chung ◽  
Mairi Sakellariadou

AbstractWe present a method to constrain the temperature of astrophysical black holes through detecting the inspiral phase of binary black hole coalescences. At sufficient separation, inspiraling black holes can be regarded as isolated objects, hence their temperature can still be defined. Due to their intrinsic radiation, inspiraling black holes lose part of their masses during the inspiral phase. As a result, coalescence speeds up, introducing a correction to the orbital phase. We show that this dephasing may allow us to constrain the temperature of inspiraling black holes through gravitational-wave detection. Using the binary black-hole coalescences of the first two observing runs of the Advanced LIGO and Virgo detectors, we constrain the temperature of parental black holes to be less than about $$ 10^9 $$ 10 9  K. Such a constraint corresponds to luminosity of about $$ 10^{-16} M_{\odot }~\mathrm{s}^{-1} $$ 10 - 16 M ⊙ s - 1 for a black hole of $$ 20 M_{\odot } $$ 20 M ⊙ , which is about 20 orders of magnitude below the peak luminosity of the corresponding gravitational-wave event, indicating no evidence for strong quantum-gravity effects through the detection of the inspiral phase.


2019 ◽  
Vol 490 (4) ◽  
pp. 5210-5216 ◽  
Author(s):  
Isobel M Romero-Shaw ◽  
Paul D Lasky ◽  
Eric Thrane

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.


Author(s):  
Sayak Datta ◽  
Sukanta Bose

AbstractWe study the quasi-normal modes (QNMs) of static, spherically symmetric black holes in f(R) theories. We show how these modes in theories with non-trivial f(R) are fundamentally different from those in general relativity. In the special case of $$f(R) = \alpha R^2$$f(R)=αR2 theories, it has been recently argued that iso-spectrality between scalar and vector modes breaks down. Here, we show that such a break down is quite general across all f(R) theories, as long as they satisfy $$f''(0)/(1+f''(0)) \ne 0$$f′′(0)/(1+f′′(0))≠0, where a prime denotes derivative of the function with respect to its argument. We specifically discuss the origin of the breaking of isospectrality. We also show that along with this breaking the QNMs receive a correction that arises when $$f''(0)/(1+f'(0)) \ne 0$$f′′(0)/(1+f′(0))≠0 owing to the inhomogeneous term that it introduces in the mode equation. We discuss how these differences affect the “ringdown” phase of binary black hole mergers and the possibility of constraining f(R) models with gravitational-wave observations. We also find that even though the iso-spectrality is broken in f(R) theories, in general, nevertheless in the corresponding scalar-tensor theories in the Einstein frame it is unbroken.


Entropy ◽  
2019 ◽  
Vol 21 (10) ◽  
pp. 1017
Author(s):  
Bogeun Gwak

We investigate the energy of the gravitational wave from a binary black hole merger by the coalescence of two Kerr black holes with an orbital angular momentum. The coalescence is constructed to be consistent with particle absorption in the limit in which the primary black hole is sufficiently large compared with the secondary black hole. In this limit, we analytically obtain an effective gravitational spin–orbit interaction dependent on the alignments of the angular momenta. Then, binary systems with various parameters including equal masses are numerically analyzed. According to the numerical analysis, the energy of the gravitational wave still depends on the effective interactions, as expected from the analytical form. In particular, we ensure that the final black hole obtains a large portion of its spin angular momentum from the orbital angular momentum of the initial binary black hole. To estimate the angular momentum released by the gravitational wave in the actual binary black hole, we apply our results to observations at the Laser Interferometer Gravitational-Wave Observatory: GW150914, GW151226, GW170104, GW170608 and GW170814.


2020 ◽  
Vol 498 (3) ◽  
pp. 3946-3963 ◽  
Author(s):  
Tomoya Kinugawa ◽  
Takashi Nakamura ◽  
Hiroyuki Nakano

ABSTRACT We performed Population III (Pop III) binary evolution using population synthesis simulations for seven different models. We found that Pop III binaries tend to be binary black holes (BBHs) with chirp mass Mchirp ∼ 30 M⊙ and they can merge in the present day, due to a long merger time. The merger rate densities of Pop III BBHs at z = 0 are in the range 3.34–21.2 $\rm yr^{-1}\,Gpc^{-3}$ which is consistent with the Advanced Laser Interferometer Gravitational Wave Observatory (aLIGO)/Advanced Virgo (aVIRGO) result of 9.7–101 $\rm yr^{-1}\,Gpc^{-3}$. These Pop III binaries might contribute some portion of the massive BBH gravitational wave (GW) sources detected by aLIGO/aVIRGO. We also calculated the redshift dependence of Pop III BBH mergers. We found that Pop III low-spin BBHs tend to merge at low redshift, while Pop III high-spin BBHs merge at high redshift, which can be confirmed by future GW detectors such as Einstein Telescope (ET), Cosmic Explorer (CE), and DECi-hertz Interferometer Gravitational wave Observatory (DECIGO). These detectors can also check the redshift dependence of the BBH merger rate and spin distribution. Our results show that, except for one model, the mean effective spin 〈χeff〉 at z = 0 lies in the range 0.02–0.3, while at z = 10 it is 0.16–0.64. Therefore, massive stellar-mass BBH detection by GWs will be key for stellar evolution study in the early Universe.


2021 ◽  
Vol 502 (3) ◽  
pp. 3879-3884
Author(s):  
Giacomo Fragione ◽  
Abraham Loeb

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.


2020 ◽  
Vol 495 (1) ◽  
pp. 536-543 ◽  
Author(s):  
Razieh Emami ◽  
Abraham Loeb

ABSTRACT We analyse triple systems composed of the supermassive black hole (SMBH) near the centre of M87 and a pair of black holes (BHs) with masses in the range of $10{-}10^3\, {\rm M}_{\odot }$. We consider the post Newtonian precession as well as the Kozai–Lidov interactions at the quadruple and octupole levels in modelling the evolution of binary black hole (BBH) under the influence of the SMBH. Kozai–Lidov oscillations enhance the gravitational wave (GW) signal in some portions of the parameter space. We identify frequency peaks and examine the detectability of GWs with LISA as well as future observatories such as μAres and DECIGO. We show examples in which GW signal can be observed with a few or all of these detectors. Multiwavelength GW spectroscopy holds the potential to discover stellar to intermediate mass BHs near the centre of M87. We estimate the rate, Γ, of collisions between the BBHs and fly-by stars at the centre of M87. Our calculation suggest $\Gamma \lt 10\, \rm {Gyr}^{-1}$ for a wide range of the mass and semimajor axes of the inner binary.


2018 ◽  
Vol 14 (S346) ◽  
pp. 449-454 ◽  
Author(s):  
Paul M. Ricker ◽  
Frank X. Timmes ◽  
Ronald E. Taam ◽  
Ronald F. Webbink

AbstractThe discovery via gravitational waves of binary black hole systems with total masses greater than 60Mʘ has raised interesting questions for stellar evolution theory. Among the most promising formation channels for these systems is one involving a common envelope binary containing a low metallicity, core helium burning star with mass ⁓30 – 40Mʘ and a black hole with mass ⁓30 – 40Mʘ. For this channel to be viable, the common envelope binary must eject more than half the giant star’s mass and reduce its orbital separation by as much as a factor of 80. We discuss issues faced in numerically simulating the common envelope evolution of such systems and present a 3D AMR simulation of the dynamical inspiral of a low-metallicity red supergiant with a massive black hole companion.


Sign in / Sign up

Export Citation Format

Share Document