Search results for "strong field"
showing 10 items of 16 documents
Gravitational wave signature of proto-neutron star convection: I. MHD numerical simulations
2021
Gravitational waves provide a unique and powerful opportunity to constrain the dynamics in the interior of proto-neutron stars during core collapse supernovae. Convective motions play an important role in generating neutron stars magnetic fields, which could explain magnetar formation in the presence of fast rotation. We compute the gravitational wave emission from proto-neutron star convection and its associated dynamo, by post-processing three-dimensional MHD simulations of a model restricted to the convective zone in the anelastic approximation. We consider two different proto-neutron star structures representative of early times (with a convective layer) and late times (when the star is…
Accretion in strong field gravity with eXTP
2019
In this paper we describe the potential of the enhanced X-ray Timing and Polarimetry (eXTP) mission for studies related to accretion flows in the strong field gravity regime around both stellar-mass and supermassive black-holes. eXTP has the unique capability of using advanced 'spectral-timing-polarimetry' techniques to analyze the rapid variations with three orthogonal diagnostics of the flow and its geometry, yielding unprecedented insight into the inner accreting regions, the effects of strong field gravity on the material within them and the powerful outflows which are driven by the accretion process.
Ab initio angle- and energy-resolved photoelectron spectroscopy with time-dependent density-functional theory
2012
We present a time-dependent density-functional method able to describe the photoelectron spectrum of atoms and molecules when excited by laser pulses. This computationally feasible scheme is based on a geometrical partitioning that efficiently gives access to photoelectron spectroscopy in time-dependent density-functional calculations. By using a geometrical approach, we provide a simple description of momentum-resolved photoemission including multiphoton effects. The approach is validated by comparison with results in the literature and exact calculations. Furthermore, we present numerical photoelectron angular distributions for randomly oriented nitrogen molecules in a short near-infrared…
Setting the photoelectron clock through molecular alignment
2020
The interaction of strong laser fields with matter intrinsically provides a powerful tool for imaging transient dynamics with an extremely high spatiotemporal resolution. Here, we study strong-field ionisation of laser-aligned molecules, and show a full real-time picture of the photoelectron dynamics in the combined action of the laser field and the molecular interaction. We demonstrate that the molecule has a dramatic impact on the overall strong-field dynamics: it sets the clock for the emission of electrons with a given rescattering kinetic energy. This result represents a benchmark for the seminal statements of molecular-frame strong-field physics and has strong impact on the interpreta…
Time- and angle-resolved photoelectron spectroscopy of strong-field light-dressed solids: prevalence of the adiabatic band picture
2022
In recent years, strong-field physics in condensed-matter was pioneered as a novel approach for controlling material properties through laser-dressing, as well as for ultrafast spectroscopy via nonlinear light-matter interactions (e.g. harmonic generation). A potential controversy arising from these advancements is that it is sometimes vague which band-picture should be used to interpret strong-field experiments: the field-free bands, the adiabatic (instantaneous) field-dressed bands, Floquet bands, or some other intermediate picture. We here try to resolve this issue by performing 'theoretical experiments' of time- and angle-resolved photoelectron spectroscopy (Tr-ARPES) for a strong-field…
Tests of General Relativity with GW170817
2019
The recent discovery by Advanced LIGO and Advanced Virgo of a gravitational wave signal from a binary neutron star inspiral has enabled tests of general relativity (GR) with this new type of source. This source, for the first time, permits tests of strong-field dynamics of compact binaries in presence of matter. In this paper, we place constraints on the dipole radiation and possible deviations from GR in the post-Newtonian coefficients that govern the inspiral regime. Bounds on modified dispersion of gravitational waves are obtained; in combination with information from the observed electromagnetic counterpart we can also constrain effects due to large extra dimensions. Finally, the polari…
Strong-field physics in the molecular frame
2019
XXI International Conference on Ultrafast Phenomena 2018, UP 2018, Hamburg, Germany, 15 Jul 2018 - 20 Jul 2018; The European physical journal / Web of Conferences 205, 07002 (2019). doi:10.1051/epjconf/201920507002
Strong-field physics using lasers and relativistic heavy ions at the high-energy storage ring hesr at fair
2014
The HESR high-energy ion storage ring at FAIR will provide unprecedented possibilities for strong-field physics using novel laser sources on relativistic heavy ions. An overview on the planning will be given.
A paradigm of fullerene
2009
We study the dynamics of an electron constrained over the surface of a rigid sphere, with geometrical parameters similar to those of the C60 fullerene, embedded in a low intensity linearly polarized laser field. The model is shown to emit odd harmonics of the laser even at very low field intensity. For more intense laser fields, the spectrum presents odd harmonics and hyper-Raman lines shaped in a broad plateau. The spectrum of the model is compared to that theoretically obtained by other authors for more realistic models of C60. It is concluded that the model can be used as a paradigm for mesoscopic molecules in the fullerene family, particularly in practical applications where it is conve…
On the dynamics of confined particles: a laser test
2017
Reduced dimensionality systems (RDS) are materials extending along one or two dimensions much more than the other(s). The degrees of freedom of the small dimension are not explored by the electrons since their energy is very large. The time dependent wave function of a particle in a short nanotube, taken as a paradigm of the RDS family, is calculated by solving the Klein–Gordon equation; the confining condition produces a small change in the mass of the particles and of the energy levels. These changes are of relativistic origin and therefore small, but can be measured by use of a weak resonant laser field which produces cumulative effects in the time development of the wave function. The s…