Search results for "Spin-flip"
showing 10 items of 23 documents
Numerical relativity simulations of thick accretion disks around tilted Kerr black holes
2015
In this work we present 3D numerical relativity simulations of thick accretion disks around tilted Kerr BH. We investigate the evolution of three different initial disk models with a range of initial black hole spin magnitudes and tilt angles. For all the disk-to-black hole mass ratios considered (0.044-0.16) we observe significant black hole precession and nutation during the evolution. This indicates that for such mass ratios, neglecting the self-gravity of the disks by evolving them in a fixed background black hole spacetime is not justified. We find that the two more massive models are unstable against the Papaloizou-Pringle (PP) instability and that those PP-unstable models remain unst…
Influence of self-gravity on the runaway instability of black-hole-torus systems.
2010
Results from the first fully general relativistic numerical simulations in axisymmetry of a system formed by a black hole surrounded by a self-gravitating torus in equilibrium are presented, aiming to assess the influence of the torus self-gravity on the onset of the runaway instability. We consider several models with varying torus-to-black hole mass ratio and angular momentum distribution orbiting in equilibrium around a non-rotating black hole. The tori are perturbed to induce the mass transfer towards the black hole. Our numerical simulations show that all models exhibit a persistent phase of axisymmetric oscillations around their equilibria for several dynamical timescales without the …
On the black hole from merging binary neutron stars: how fast can it spin?
2013
The merger of two neutron stars will in general lead to the formation of a torus surrounding a black hole whose rotational energy can be tapped to potentially power a short gamma-ray burst. We have studied the merger of equal-mass binaries with spins aligned with the orbital angular momentum to determine the maximum spin the black hole can reach. Our initial data consists of irrotational binaries to which we add various amounts of rotation to increase the total angular momentum. Although the initial data violates the constraint equations, the use of the constraint-damping CCZ4 formulation yields evolutions with violations smaller than those with irrotational initial data and standard formul…
SKYRME-RANDOM-PHASE-APPROXIMATION DESCRIPTION OF SPIN-FLIP AND ORBITAL M1 GIANT RESONANCES
2010
The self-consistent separable random-phase approximation (SRPA) with Skyrme forces is extended to the case of magnetic excitations and applied to the description of spin-flip and orbital M1 giant resonances in the isotopic chain 142-152 Nd . The Skyrme forces SkT6, SkM*, SLy6 and SkI3 are used. The calculations show an onset of the scissors mode with increasing deformation. A specific three-peak structure of the spin-flip response is found and explained by particular neutron and proton spin-flip transitions. Although the employed forces provide an acceptable qualitative description, the Skyrme functional still needs further improvement to reproduce quantitatively the experiment for spin mo…
Observation of Spin Flips with a Single Trapped Proton
2011
Radio-frequency induced spin transitions of one individual proton are observed for the first time. The spin quantum jumps are detected via the continuous Stern-Gerlach effect, which is used in an experiment with a single proton stored in a cryogenic Penning trap. This is an important milestone towards a direct high-precision measurement of the magnetic moment of the proton and a new test of the matter-antimatter symmetry in the baryon sector.
Shock waves and QPOs in 2D rotating accretion flows around black holes
2008
We examine numerically shock waves formed in 2D rotating accretion flows around a stellar‐mass and a supermassive black holes, while taking account of the cooling and heating of the gas and the radiation transport. As the results, we obtain general properties of the shock oscillations and the luminosity behaviors as QPOs independent of the black hole masses.
gFactor of HydrogenlikeSi13+28
2011
We determined the experimental value of the $g$ factor of the electron bound in hydrogenlike $^{28}\mathrm{Si}^{13+}$ by using a single ion confined in a cylindrical Penning trap. From the ratio of the ion's cyclotron frequency and the induced spin flip frequency, we obtain $g=1.995\text{ }348\text{ }958\text{ }7(5)(3)(8)$. It is in excellent agreement with the state-of-the-art theoretical value of 1.995 348 958 0(17), which includes QED contributions up to the two-loop level of the order of $(Z\ensuremath{\alpha}{)}^{2}$ and $(Z\ensuremath{\alpha}{)}^{4}$ and represents a stringent test of bound-state quantum electrodynamics calculations.
Beyond linear response spectroscopy of ultracold fermi gases.
2005
We study RF-spectroscopy of ultracold Fermi gas by going beyond the linear response in the field-matter interaction. Higher order perturbation theory allows virtual processes and energy conservation beyond the single particle level. We formulate an effective higher order theory which agrees quantitatively with experiments on the pairing gap, and is consistent with the absence of the mean-field shift in the spin-flip experiment.
Steady state shocks in accretion disks around a Kerr black hole
1994
Results of numerical simulations of shock solutions in a geometrical thin accretion disk around a Kerr black hole (BH) are presented. Using the smoothed particle hydrodynamics (SPH) technique, the influence of the central object is included by means of an effective potential, We first present the theory of standing shock formation in accretion disks around a Kerr black hole, and show that the results of our numerical simulation agree very well with the theoretical results. We find that the shocks in an inviscid flow are very stable. We also remove the ambiguity prevalent regarding the location and stability of shocks in adiabatic flows. Finally we sketch some of the astrophysical consequenc…
QPOs expected in rotating accretion flows around a supermassive black hole
2006
AbstractIt is well known that rotating inviscid accretion flows with adequate injection parameters around black holes could form shock waves close to the black holes, after the flow passes through the outer sonic point and can be virtually stopped by the centrifugal force. We numerically examine such shock waves in 2D accretion flows with 10−5 to 106 Eddington critical accretion rates around a supermassive black hole with 106M⊙. As the results, the luminosities show QPO phenomena with modulations of a factor 2–3 and with quasi-periods of a few to several hours.