Abstract: Recently, the anomalous decay rate of quasinormal modes has been studied for some geometries under scalar field perturbations, which occurs when the longest-lived modes are the ones with higher angular number, as well as the existence of a critical scalar field mass, i.e., the value of scalar field mass such that the decay rate does not depend appreciably on the angular number, and beyond which the behavior of the decay rate is inverted. Here, we consider the propagation of fermionic fields in the background of Schwarzschild--de Sitter black holes, and we show that the anomalous decay rate behavior and the fine structure, related to the coupling between the chirality and the mass of the field, can be observed in the fermionic spectrum.

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Topics: Scalar field (61%), Schwarzschild radius (56%), Field (physics) (54%) ... show more

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10 results found

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Abstract: On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160) Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

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Topics: Stellar black hole (81%), Rotating black hole (77%), Binary black hole (76%) ... show more

4,375 Citations

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Roberto Fontana^{1}, P. A. González^{2}, Eleftherios Papantonopoulos^{3}, Yerko Vásquez^{4}•Institutions (4)

Abstract: The anomalous decay rate of the quasinormal modes occurs when the longest-lived modes are the ones with a higher angular number. Such behavior has been recently studied in different static spacetimes for scalar and fermionic perturbations, being observed in both cases. In this work, we extend the existent studies to the charged spacetimes---namely, the Reissner-Nordstr\"om, the Reissner-Nordstr\"om de Sitter, and the Reissner-Nordstr\"om anti--de Sitter black holes. We show that the anomalous decay rate behavior of the scalar field perturbations is present for every charged geometry in the photon sphere modes, with the existence of a critical scalar field mass whenever $\mathrm{\ensuremath{\Lambda}}\ensuremath{\ge}0$. In general, this critical value of mass increases with the raising of the black hole charge, thus rendering a minimum in the Schwarzschild limit. We also study the dominant mode/family for the massless and massive scalar fields in these geometries, showing a nontrivial dominance of the spectra that depends on the black hole mass and charge.

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Topics: Schwarzschild radius (59%), Scalar field (58%), Photon sphere (56%) ... show more

11 Citations

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Almendra Aragón^{1}, P. A. González^{1}, Eleftherios Papantonopoulos^{2}, Yerko Vásquez^{3}•Institutions (3)

Abstract: We study the propagation of scalar fields in the background of an asymptotically de-Sitter black hole solution in $f(R)$ gravity, with the aim of analyzing the existence of an anomalous behavior in the quasinormal modes (QNMs) spectrum in alternatives theories of gravity and to study the stability of the scalar field propagation. We study the QNMs for various overtone numbers of different branches that they depend on a parameter $\beta$ which appears in the metric and characterizes the $f(R)$ gravity. For small deviations from the Schwarzschild-dS black hole the anomalous behavior in the QNMs is present, and the critical value of the mass of the scalar field depends on the parameter $\beta$ while for large deviations the anomalous behavior does not appear. Also, the critical mass of the scalar field increases when the overtone number increases until the $f(R)$ gravity parameter $\beta$ approaches the near extremal limit at which the critical mass of the scalar field does not depend anymore on the overtone number. Also, we find that the imaginary part of the quasinormal frequencies is always negative for all branches leading to a stable propagation of the scalar fields in this background.

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Topics: Scalar field (62%), f(R) gravity (60%), Scalar (mathematics) (57%) ... show more

7 Citations

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Almendra Aragón^{1}, P. A. González^{1}, Eleftherios Papantonopoulos^{2}, Yerko Vásquez^{3}•Institutions (3)

Abstract: We study the propagation of scalar fields in the background of an asymptotically de Sitter black hole solution in f(R) gravity. The aim of this work is to analyze in modified theories of gravity the existence of an anomalous decay rate of the quasinormal modes (QNMs) of a massive scalar field which was recently reported in Schwarzschild black hole backgrounds, in which the longest-lived modes are the ones with higher angular number, for a scalar field mass smaller than a critical value, while that beyond this value the behavior is inverted. We study the QNMs for various overtone numbers and they depend on a parameter $$\beta $$
which appears in the metric and characterizes the f(R) gravity. For small $$\beta $$
, i.e. small deviations from the Schwarzschild–dS black hole the anomalous behavior in the QNMs is present for the photon sphere modes, and the critical value of the mass of the scalar field depends on the parameter $$\beta $$
while for large $$\beta $$
, i.e. large deviations, the anomalous behavior and the critical mass does not appear. Also, the critical mass of the scalar field increases when the overtone number increases until the f(R) gravity parameter $$\beta $$
approaches the near extremal limit at which the critical mass of the scalar field does not depend anymore on the overtone number. The imaginary part of the quasinormal frequencies is always negative leading to a stable propagation of the scalar fields in this background.

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Topics: Scalar field (60%), f(R) gravity (59%), Scalar (mathematics) (56%) ... show more

5 Citations

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Abstract: In this paper, we show how the quasinormal modes (QNMs) arise from the perturbations of massive scalar fields propagating in the curved background by using the artificial neural networks. To this end, we architect a special algorithm for the feedforward neural network method (FNNM) to compute the QNMs complying with the certain types of boundary conditions. To test the reliability of the method, we consider two black hole spacetimes whose QNMs are well-known: $4D$ pure de Sitter (dS) and five-dimensional Schwarzschild anti-de Sitter (AdS) black holes. Using the FNNM, the QNMs of are computed numerically. It is shown that the obtained QNMs via the FNNM are in good agreement with their former QNM results resulting from the other methods. Therefore, our method of finding the QNMs can be used for other curved spacetimes that obey the same boundary conditions.

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Topics: Schwarzschild radius (52%), Black hole (51%)

2 Citations

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58 results found

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B. P. Abbott^{1}, Richard J. Abbott^{1}, T. D. Abbott^{2}, Matthew Abernathy^{1} +1008 more•Institutions (96)

Abstract: On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of $1.0 \times 10^{-21}$. It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203 000 years, equivalent to a significance greater than 5.1 {\sigma}. The source lies at a luminosity distance of $410^{+160}_{-180}$ Mpc corresponding to a redshift $z = 0.09^{+0.03}_{-0.04}$. In the source frame, the initial black hole masses are $36^{+5}_{-4} M_\odot$ and $29^{+4}_{-4} M_\odot$, and the final black hole mass is $62^{+4}_{-4} M_\odot$, with $3.0^{+0.5}_{-0.5} M_\odot c^2$ radiated in gravitational waves. All uncertainties define 90% credible intervals.These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

... read more

Topics: Binary black hole (60%), Black hole (58%), Primordial black hole (54%) ... show more

8,011 Citations

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Abstract: On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160) Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

... read more

Topics: Stellar black hole (81%), Rotating black hole (77%), Binary black hole (76%) ... show more

4,375 Citations

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01 Jan 1983-

Abstract: In a course of lectures on the ‘underlying mathematical structures of classical gravitation theory’ given in 1978, Brandon Carter began with the statement ‘If I had been asked five years ago to prepare a course of lectures on recent developments in classical gravitation theory, I would not have hesitated on the classical theory of black holes as a central topic of discussion. However, the most important developments in gravitational theory during the last three or four years have not been in the classical domain at all…’ Carter is undoubtedly right in his assessment that the mathematical theory of black holes has not been in the mainstream of research in relativity since 1973. I therefore find it difficult to understand why the organizers of this meeting should have chosen precisely this topic for the opening talk of this meeting. But I am grateful to them for their courtesy in assigning to me this privilege.

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Topics: Mathematical theory (54%)

4,162 Citations

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Abstract: It is shown that a Schwarzschild singularity, spherically symmetrical and endowed with mass, will undergo small vibrations about the spherical form and will therefore remain stable if subjected to a small nonspherical perturbation.

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Topics: Schwarzschild radius (59%), Singularity (59%)

1,803 Citations

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Abstract: Perturbations of stars and black holes have been one of the main topics of relativistic astrophysics for the last few decades. They are of particular importance today, because of their relevance to gravitational wave astronomy. In this review we present the theory of quasi-normal modes of compact objects from both the mathematical and astrophysical points of view. The discussion includes perturbations of black holes (Schwarzschild, Reissner-Nordstrom, Kerr and Kerr-Newman) and relativistic stars (non-rotating and slowly-rotating). The properties of the various families of quasi-normal modes are described, and numerical techniques for calculating quasi-normal modes reviewed. The successes, as well as the limits, of perturbation theory are presented, and its role in the emerging era of numerical relativity and supercomputers is discussed.

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Topics: Numerical relativity (66%), Black hole (64%), Binary black hole (61%) ... show more

1,439 Citations