Direct constraints on ultra-light boson mass from searches for continuous gravitational waves

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**hole**. Once formed, the boson cloud is expected to emit a nearly periodic, long-duration, gravitational-wave signal. For boson masses in the range $(10^{-13}-10^{-11})$ eV, and stellar mass

**black**holes, such signals are potentially detectable by gravitational wave detectors, like Advanced LIGO and Virgo. In this {\it Letter} we present full band upper limits for a generic all-sky search for periodic gravitational waves in LIGO O2 data, and use them to derive - for the first time - direct constraints on the ultra-light scalar boson field mass.

6/10 relevant

arXiv

Timelike Geodesics in Naked Singularity and **Black** **Hole** Spacetimes II

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**hole**spacetime. Expand abstract.

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**hole**. We plot the orbit equations and find the Perihelion precession of the orbits of particles in the BST and JNW spacetimes and compare these with the Schwarzschild

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**hole**spacetime. We find and discuss different distinguishing properties in the effective potentials and orbits of particle in BST, JNW and Schwarzschild spacetimes, and the particle trajectories are shown for the matching of BST with an external Schwarzschild spacetime. We show that the nature of perihelion precession of orbits in BST and Schwarzschild spacetimes are similar, while in the JNW case the nature of perihelion precession of orbits is opposite to that of the Schwarzschild and BST spacetimes. Other interesting and important features of these orbits are pointed out.

7/10 relevant

arXiv

Emergent **Black** **Hole** Dynamics in Critical Floquet Systems

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**holes**resulting in a singular concentration of energy at their center. Expand abstract.

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**holes**. The Hawking temperature serves as an order parameter which distinguishes between heating and non-heating phases. Beyond a time scale determined by the inverse Hawking temperature, excitations are absorbed by the

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**holes**resulting in a singular concentration of energy at their center. We obtain these results analytically within conformal field theory, capitalizing on a mapping to sine-square deformed field theories. Furthermore, by means of numerical calculations for an interacting XXZ spin-1/2 chain, we demonstrate that our findings survive lattice regularization.

9/10 relevant

arXiv

Induced Spins from Scattering Experiments of Initially Nonspinning **Black**
**Holes**

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**holes**pass by one another on a scattering trajectory, we might expect the tidal interaction to spin up each

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**hole**. We present the first exploration of this effect, appearing at fourth post-Newtonian order, with full numerical relativity calculations. The basic set up for the calculations involves two free parameters: the initial boost of each

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**hole**and the initial angle between their velocity vectors, with zero angle corresponding to a head-on trajectory. To minimize gauge effects, we measure final spins only if the

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**holes**reach a final separation of at least $20M$. Fixing the initial boost, we find that as the initial angle decreases toward the scattering/non-scattering limit, the spin-up grows nonlinearly. In addition, as initial boosts are increased from $0.42c$ to $0.78c$, the largest observed final dimensionless spin on each

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**hole**increases nonlinearly from $0.02$ to $0.20$. Based on these results, we conclude that much higher spin-ups may be possible with larger boosts, although achieving this will require improved numerical techniques.

10/10 relevant

arXiv

Linearized Stability of Bardeen de-Sitter Thin-Shell Wormholes

**hole**is crafted by the cut-and-paste method of two Bardeen de-Sitter

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**holes**using Darmois-Israel formalism. Expand abstract.

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**holes**using Darmois-Israel formalism. Dynamics and stability of the wormhole is also studied around the static solutions of the linearized radial perturbations at the throat of the wormhole.

4/10 relevant

Preprints.org

Separability of the Klein-Gordon equation for rotating spacetimes obtained from Newman-Janis algorithm

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**holes**. Expand abstract.

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**holes**. In addition, it has been recently shown that the general stationary and axisymmetric spacetime generated through NJA allows the separability of the Hamilton-Jacobi equation, rendering the geodesic equations separable. In this work, we further study the conditions for a separable Klein-Gordon equation in such a general spacetime. The relations between the NJA spacetime and other parameterized axially symmetric spacetimes in the literature are also discussed.

4/10 relevant

arXiv

Does **black**-**hole** growth depend fundamentally on host-galaxy compactness?

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**hole**(BH) growth and host-galaxy compactness have been found observationally, which may provide insight into BH-galaxy coevolution: compact galaxies might have large amounts of gas in their centers due to their high mass-to-size ratios, and simulations predict that high central gas density can boost BH accretion. However, it is not yet clear if BH growth is fundamentally related to the compactness of the host galaxy, due to observational degeneracies between compactness, stellar mass ($M_\bigstar$), and star formation rate (SFR). To break these degeneracies, we carry out systematic partial-correlation studies to investigate the dependence of sample-averaged BH accretion rate ($\rm \overline{BHAR}$) on the compactness of host galaxies, represented by the surface-mass density, $\Sigma_\rm e$, or the projected central surface-mass density within 1 kpc, $\Sigma_1$. We utilize 8842 galaxies with H < 24.5 in the five CANDELS fields at z = 0.5-3. We find that $\rm \overline{BHAR}$ does not significantly depend on compactness when controlling for SFR or $M_\bigstar$ among bulge-dominated galaxies and galaxies that are not dominated by bulges, respectively. However, when testing is confined to star-forming galaxies at z = 0.5-1.5, we find that the $\rm \overline{BHAR}$-$\Sigma_1$ relation is not simply a secondary manifestation of a primary $\rm \overline{BHAR}$-$M_\bigstar$ relation, which may indicate a link between BH growth and the gas density within the central 1 kpc of galaxies.

7/10 relevant

arXiv

Searching for Eccentricity: Signatures of Dynamical Formation in the First Gravitational-Wave Transient Catalogue of LIGO and Virgo

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**holes**are thought to form primarily via two channels: isolated evolution and dynamical formation. The component masses, spins, and eccentricity of a binary

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**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

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**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 0.06 with 90\% confidence at a reference frequency of 10 Hz. These upper limits do not significantly constrain the fraction of LIGO-Virgo events formed dynamically in globular clusters, because only $\sim5\%$ 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.

7/10 relevant

arXiv

GUP **black** **hole** remnants in quadratic gravity

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**holes**, for a precise combination of the GUP parameter and the coupling constants that drive the gravitational interaction in quadratic gravity, yielding absolutely stable black

**hole**remnants. Expand abstract.

**black**holes, for a precise combination of the GUP parameter and the coupling constants that drive the gravitational interaction in quadratic gravity, yielding absolutely stable

**black**

**hole**remnants.

10/10 relevant

arXiv

**Black** **holes** in the low mass gap: Implications for gravitational wave
observations

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**hole**remnants of mass $\sim 3$--$4\,M_{\odot}$, thus populating the putative \emph{low mass gap} between neutron stars and stellar-mass

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**holes**. If these low-mass

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**holes**are in dense astrophysical environments, mass segregation could lead to "second-generation" compact binaries merging within a Hubble time. We estimate the probability of producing low-mass compact binary mergers through this mechanism, and investigate their observable signatures. We show that this unique population of objects will be uncovered by third-generation gravitational-wave detectors, such as Cosmic Explorer and Einstein Telescope. Future joint measurements of chirp mass ${\cal M}$ and effective spin $\chi_{\rm eff}$ could clarify the formation scenario of compact objects in the low mass gap.

10/10 relevant

arXiv