Analytical theory of Hawking radiation in dispersive media

Leónhardt, Ulf; Robertson, Scott

doi:10.1088/1367-2630/14/5/053003

Cited by 41 publications

(68 citation statements)

References 34 publications

(74 reference statements)

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“…subcritical flows does not follow a Planck law, even approximately. This is in agreement with [19,20,31,32], where a temperature increasing with ω was observed for flows which are not symmetric with respect to the position of the horizon. So, while the effective temperature at any one frequency is Hawking-like in being approximately proportional to κ R , the constant of proportionality varies with ω so that the spectrum as a whole is not a thermal one.…”

Section: High-frequency Regimesupporting

confidence: 90%

Scattering of gravity waves in subcritical flows over an obstacle

2016

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We numerically study the scattering coefficients of linear water waves on stationary flows above a localized obstacle. We compare the scattering on trans-and subcritical flows, and then focus on the latter which have been used in recent analog gravity experiments. The main difference concerns the magnitude of the mode amplification: whereas transcritical flows display a large amplification (which is generally in good agreement with the Hawking prediction), this effect is heavily suppressed in subcritical flows. This is due to the transmission across the obstacle for frequencies less than some critical value. As a result, subcritical flows display high-and low-frequency behaviors separated by a narrow band around the critical frequency. In the low-frequency regime, transmission of long wavelengths is accompanied by non-adiabatic scattering into short wavelengths, whose spectrum is approximately linear in frequency. By contrast, in the high-frequency regime, no simple description seems to exist. In particular, for obstacles similar to those recently used, we observe that the upstream slope still affects the scattering on the downstream side because of some residual transmission.

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Section: High-frequency Regimesupporting

confidence: 90%

Scattering of gravity waves in subcritical flows over an obstacle

2016

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“…Thus necessarily trans-Planckian energies become involved, for which the physics is at present speculative. Similar issues regarding kinematical phenomena for quantum fields propagating on a fixed curved spacetime arise when tracing back Hawking radiation emission all the way down to the black hole horizon [5][6][7][8].…”

mentioning

confidence: 89%

Probing the Scale Invariance of the Inflationary Power Spectrum in Expanding Quasi-Two-Dimensional Dipolar Condensates

Chä

Fischer

2017

Phys. Rev. Lett.

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We consider an analogue de Sitter cosmos in an expanding quasi-two-dimensional Bose-Einstein condensate with dominant dipole-dipole interactions between the atoms or molecules in the ultracold gas. It is demonstrated that a hallmark signature of inflationary cosmology, the scale invariance of the power spectrum of inflaton field correlations, experiences strong modifications when, at the initial stage of expansion, the excitation spectrum displays a roton minimum. Dipolar quantum gases thus furnish a viable laboratory tool to experimentally investigate, with well-defined and controllable initial conditions, whether primordial oscillation spectra deviating from Lorentz invariance at trans-Planckian momenta violate standard predictions of inflationary cosmology.

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“…However analogue effects depends on the medium through the dispersion relation. Such deviation has been studied for fluid systems in flat Minkowski spacetime for very simplified dispersion relations, see, e.g., [34,35]. However study of such deviation in black hole accretion analogue system is way more involved as in this system not only the background spacetime geometry is curved but also the matter flow can have different geometry which influences the acoustic surface gravity.…”

Section: Accreting Black Holes As Analogue Systemsmentioning

confidence: 99%

Relativistic sonic geometry for isothermal accretion in the Schwarzschild metric

Shaikh

Firdousi

Das

2017

Class. Quantum Grav.

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Abstract. In this work, we perform linear perturbation on general relativistic isothermal accretion onto a non-rotating astrophysical black hole to study the salient features of the corresponding emergent acoustic metric. For spherically symmetric accretion as well as for the axially symmetric matter flow for three different geometric configuration of matter, we perturb the velocity potential, the mass accretion rate, and the integral solution of the time independent part of the general relativistic Euler equation to obtain such acoustic geometry. We provide the procedure to locate the acoustic horizon and identify such horizon with the transonic surfaces of the accreting matter through the construction of the corresponding causal structures. We then discuss how one can compute the value of the acoustic surface gravity in terms of the accretion variable corresponding to the background flow solutions -i.e., stationary integral transonic accretion solutions for different matter geometries. We show that the salient features of the acoustic geometry is independent of the physical variable we perturb, but sensitively depends on the geometric configuration of the black hole accretion disc.

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Analytical theory of Hawking radiation in dispersive media

Cited by 41 publications

References 34 publications

Scattering of gravity waves in subcritical flows over an obstacle

Scattering of gravity waves in subcritical flows over an obstacle

Probing the Scale Invariance of the Inflationary Power Spectrum in Expanding Quasi-Two-Dimensional Dipolar Condensates

Relativistic sonic geometry for isothermal accretion in the Schwarzschild metric

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