We present a surrogate numerical-relativity model for close hyperbolic black-hole encounters with equal masses and spins aligned with the orbital momentum. Our model, generated in terms of the Newman–Penrose scalar ...
We present a surrogate numerical-relativity model for close hyperbolic black-hole encounters with equal masses and spins aligned with the orbital momentum. Our model, generated in terms of the Newman–Penrose scalar ψ4, spans impact parameters b/M∈[11,15] and spin components χi∈[−0.5,0.5], modeling the (ℓ,m)=(2,0), (2,±2), (3,±2), and (4,±4) emission multipoles. The model is faithful to numerical-relativity simulations, yielding mismatches lower than 10−3. We test the ability of our model to recover the parameters of numerically simulated signals. We find that, despite the high accuracy of the model, parameter inference struggles to correctly capture the parameters of the source even for SNRs as large as 50 due to the strong degeneracies present in the parameter space. This indicates that correctly identifying these systems will require extremely large signal loudness, which is only typical of third generation detectors. Nevertheless, we also find that, if one attempts to infer certain combinations of such degenerated parameters, there might be a chance to prove the existence of this type of event, even with the current ground-based detectors, as long as these combinations make sense astrophysically and cosmologically.
The use of Multiple Choice Questions (MCQ) in written tests, supported by the digital scan and automatic correction, has been evaluated using the application of Item Response Theory methodology. A simple detection of ...
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Increasingly, reduction of water availability has been a reality, and population growth, pollution, and climate change have contributed to exacerbating this problem. Dry periods, which occur when precipitation is lowe...
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We show that certain vanishing properties defining closed subspaces of generalized Morrey spaces are preserved under the action of various classical operators of harmonic analysis, such as maximal operators, singular-...
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A central feature of the most elementary rotating black hole (BH) solution in general relativity is the Kerr bound which, for vacuum Kerr BHs, can be expressed either in terms of the Arnowitt-Deser-Misner (ADM) or hor...
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A central feature of the most elementary rotating black hole (BH) solution in general relativity is the Kerr bound which, for vacuum Kerr BHs, can be expressed either in terms of the Arnowitt-Deser-Misner (ADM) or horizon “charges.” However, this bound is not a fundamental property of general relativity and stationary, asymptotically flat, and regular (on and outside an event horizon) BHs are known to violate the Kerr bound, in terms of both their ADM and horizon quantities. Examples include the recently discovered Kerr BHs with scalar [C. A. R. Herdeiro and E. Radu, Phys. Rev. Lett. 112, 221101 (2014)] or Proca hair [C. Herdeiro, E. Radu, and H. Runarsson, arXiv:1603.02687]. Here, we point out the fact that the Kerr bound in terms of horizon quantities is also violated by well-known rotating and charged solutions which are known in closed form, such as the Kerr-Newman and Kerr-Sen BHs. Moreover, for the former we observe that the Reissner-Nordström (RN) bound is also violated in terms of horizon quantities, even in the static (i.e., RN) limit. By contrast, for the latter the existence of charged matter outside the horizon allows for a curious invariance of the charge-to-mass ratio between the ADM and horizon quantities. Regardless of the Kerr bound violation, we show that in all cases the event horizon linear velocity [C. A. R. Herdeiro and E. Radu, Int. J. Mod. Phys. D 24, 1544022 (2015)] never exceeds the speed of light. Finally, we suggest a new type of informative parametrization for BH spacetimes where part of the asymptotic charge is supported outside the horizon.
We study the horizon geometry of Kerr black holes (BHs) with scalar synchronized hair [1], a family of solutions of the Einstein-Klein-Gordon system that continuously connects to vacuum Kerr BHs. We identify the regio...
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We study the horizon geometry of Kerr black holes (BHs) with scalar synchronized hair [1], a family of solutions of the Einstein-Klein-Gordon system that continuously connects to vacuum Kerr BHs. We identify the region in parameter space wherein a global isometric embedding in Euclidean 3-space, E3, is possible for the horizon geometry of the hairy BHs. For the Kerr case, such embedding is possible iff the horizon dimensionless spin jH (which equals the total dimensionless spin, j), the sphericity s and the horizon linear velocity vH are smaller than critical values, j(S),s(S),vH(S), respectively. For the hairy BHs, we find that jH
In this paper the current usage of active Massive Open Line Courses (MOCC) is analysed. First a systematic literature revision is performed, in order to identify and classify the published works and the existing devel...
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We obtain an invertibility characterization for Wiener‐Hopf plus Hankel operators with almost periodic symbols on weighted Lebesgue spaces Lp(R+,w), where 1<p<∞ and w belongs to a subclass of Muckenhoupt weigh...
We obtain an invertibility characterization for Wiener‐Hopf plus Hankel operators with almost periodic symbols on weighted Lebesgue spaces Lp(R+,w), where 1
Upper bounds for the kernel dimension of singular integral operators with orientation‐preserving Carleman shift are obtained. This is implemented by using some estimates which are derived with the help of certain exp...
Upper bounds for the kernel dimension of singular integral operators with orientation‐preserving Carleman shift are obtained. This is implemented by using some estimates which are derived with the help of certain explicit operator relations. In particular, the interplay between classes of operators with and without Carleman shifts have a preponderant importance to achieve the mentioned bounds.
In this paper we introduce two integral transforms involving the Legendre function in the kernel (see the operators I0+α,β,μ,v and I−α,β,μ,v . defined below) which generalize the classical Liouville fractional i...
In this paper we introduce two integral transforms involving the Legendre function in the kernel (see the operators I0+α,β,μ,v and I−α,β,μ,v . defined below) which generalize the classical Liouville fractional integrals. Then, we study their boundedness as operators mapping the space ℒv,r into the spaces ℒv−α,r. Moreover, we calculate the Mellin transform of the fractional integrals presented in this paper.
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