188 citations · 747 across the 28 of their papers we have counts for
12 papers · 1 filter
Relativistic collapse of axion stars
Florent Michel, Ian G. Moss
We study the gravitational collapse of an axion field in null coordinates, assuming spherical symmetry. Compared with previous studies, we use a simpler numerical scheme which can…
Gravity waves on modulated flows downstream from an obstacle: The transcritical case
Florent Michel, Renaud Parentani, Scott Robertson
Periodic spatial variations of some parameter arise in analogue gravity experiments aimed at detecting the analogue version of the Hawking effect in a white hole flow. Having the s…
Nonlinear and quantum effects in analogue gravity
Florent Michel
The present thesis deals with some properties of classical and quantum scalar fields in an inhomogeneous and/or time-dependent background, focusing on models where the latter can b…
Scattering of gravity waves in subcritical flows over an obstacle
Scott Robertson, Florent Michel, Renaud Parentani
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, an…
Dynamical instabilities and quasi-normal modes, a spectral analysis with applications to black-hole physics
Antonin Coutant, Florent Michel, Renaud Parentani
Black hole dynamical instabilities have been mostly studied in specific models. We here study the general properties of the complex-frequency modes responsible for such instabiliti…
Mode mixing in sub- and trans-critical flows over an obstacle: When should Hawking's predictions be recovered?
Florent Michel, Renaud Parentani
We reexamine the scattering coefficients of shallow water waves blocked by a stationary counter current over an obstacle. By considering series of background flows, we show that th…
Black hole radiation in the presence of a universal horizon
Florent Michel, Renaud Parentani
In Hořava and Einstein-Æther theories of modified gravity, in spite of the violation of Lorentz invariance, spherically-symmetric stationary black hole solutions possess an inner u…
Slow Sound in a duct, effective transonic flows and analogue black holes
Yves Aurégan, Pierre Fromholz, Florent Michel +2
We propose a new system suitable for studying analogue gravity effects, consisting of a gas flowing in a duct with a compliant wall. Effective transonic flows are obtained from uni…
Non-linear effects in time-dependent transonic flows: An analysis of analogue black hole stability
Florent Michel, Renaud Parentani
We study solutions of the one-dimensional Gross-Pitaevskii equation to better understand dynamical instabilities occurring in flowing atomic condensates. Whereas transonic stationa…
Wave blocking and partial transmission in subcritical flows over an obstacle
Léo-Paul Euvé, Florent Michel, Renaud Parentani +1
We study and measure the transmission coefficient of counter-propagating shallow-water waves produced by a wave generator and scattered by an obstacle. To precisely compare theoret…
Suppression of infrared instability in trans-sonic flows by condensation of zero-frequency short wave length phonons
Xavier Busch, Florent Michel, Renaud Parentani
We analyze the peculiar infrared instability that characterizes stationary inhomogeneous flows when their velocity crosses the sound speed by decreasing values. For definiteness, w…
Probing the thermal character of analogue Hawking radiation for shallow water waves?
Florent Michel, Renaud Parentani
We study and numerically compute the scattering coefficients of shallow water waves blocked by a stationary counterflow. When the flow is transcritical, the coefficients closely fo…