scholarly journals Three-dimensional two-layer outer gap model: Fermi energy-dependent light curves of the Vela pulsar

2011 ◽  
Vol 414 (3) ◽  
pp. 2664-2673 ◽  
Author(s):  
Y. Wang ◽  
J. Takata ◽  
K. S. Cheng
2021 ◽  
Author(s):  
Monica Barnard ◽  
Christo Venter ◽  
Alice Kust Harding ◽  
Constantinos Kalapotharakos ◽  
Tyrel J. Johnson

2013 ◽  
Vol 9 (S303) ◽  
pp. 318-319 ◽  
Author(s):  
P. C. Fragile ◽  
P. Anninos ◽  
S. D. Murray

AbstractUsing three-dimensional, moving-mesh simulations, we investigate the future evolution of the recently discovered gas cloud G2 traveling through the galactic center. From our simulations we expect an average feeding rate onto Sgr A* in the range of (5−19) × 10−8M⊙ yr−1 beginning in 2014. This accretion varies by less than a factor of three on timescales ∼ 1 month, and shows no more than a factor of 10 difference between the maximum and minimum observed rates within any given model. These rates are comparable to the current estimated accretion rate in the immediate vicinity of Sgr A*, although they represent only a small (< 10%) increase over the current expected feeding rate at the effective inner boundary of our simulations (racc = 750 RS ∼ 1015 cm). We also explore multiple possible equations of state to describe the gas. In examining the Br-γ light curves produced from our simulations, we find that all of our isothermal models predict significant (factor of 10) enhancements in the luminosity of G2 as it approaches pericenter, in conflict with observations. Models that instead allow the cloud to heat as it is compressed do better at matching observations.


1991 ◽  
Vol 11 (3-4) ◽  
pp. 291-302
Author(s):  
A. Aguilar ◽  
M. Albertí ◽  
R. Blasco ◽  
M. Gilibert ◽  
X. Giménez ◽  
...  

The resonant reactivity of three elementary Heavy–Light–Heavy reactions is presented and discussed. Collinear reactivity, in which a vibrational adiabatic model is constructed, is used for a detailed analysis of resonance phenomena, which appear as a direct consequence of transition state metastable states in the strong interaction region of the potential energy surface. Their influence on the detailed mechanism of the elementary process is also discussed. The shape of the resonant peak, and the phase and the Argand plot of the S-matrix are used for a further characterization.Three-dimensional approximate calculations are used to test the evolution of the energy dependent structure present in detailed quantities when sums and integrations over all partial waves contributing to reaction are taken into account to obtain the usual averaged global quantities such as integral state-to-state cross sections.


2012 ◽  
Vol 8 (S290) ◽  
pp. 201-202
Author(s):  
Giuseppe Di Bernardo ◽  
Ulf Torkelsson

AbstractThe magnetorotational instability (MRI) is widely believed to be the source of turbulence in accretion discs. This turbulence is responsible for the anomalous angular momentum transport in accretion discs. The turbulence will affect other aspects of the dynamics of the disc as well, and we will concentrate on two such issues: a) what kind of oscillations can be excited by the turbulence itself, and b) how the turbulence is interacting with modes that have been excited by some other agent. This is of interest in understanding the quasi-periodic oscillations (QPOs) that have been observed in the X-ray light curves of accreting neutron star and black hole binaries. We carry out local three dimensional (3D) magnetohydrodynamic simulations of a keplerian differentially rotating accretion disc, using a shearing box configuration taking in account the effects of the vertical stratification.


Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3364
Author(s):  
Gennady M. Gusev ◽  
Ze D. Kvon ◽  
Alexander D. Levin ◽  
Nikolay N. Mikhailov

The thermoelectric response of 80 nm-thick strained HgTe films of a three-dimensional topological insulator (3D TI) has been studied experimentally. An ambipolar thermopower is observed where the Fermi energy moves from conducting to the valence bulk band. The comparison between theory and experiment shows that the thermopower is mostly due to the phonon drag contribution. In the region where the 2D Dirac electrons coexist with bulk hole states, the Seebeck coefficient is modified due to 2D electron–3D hole scattering.


2020 ◽  
Vol 2020 (3) ◽  
Author(s):  
M Dehghani ◽  
M Badpa

Abstract The coupled scalar, electromagnetic, and gravitational field equations of Einstein–dilaton gravity theory have been solved in a three-dimensional energy-dependent spacetime and in the presence of power-law nonlinear electrodynamics. The scalar potential is written as the linear combination of two exponential functions, and two families of three-dimensional dilatonic black hole solutions have been introduced which indicate the impacts of rainbow functions on the spacetime geometry. Through consideration of curvature scalars, it has been found that the asymptotic behavior of the solutions is neither flat nor anti-de Sitter. It has been illustrated that, with a suitable choice of parameters, the solutions can produce the two-horizon, extreme and naked singularity black holes. By calculating the black hole charge, mass, entropy, temperature, and electric potential, it has been proved that they fulfill the standard form of the first law of black hole thermodynamics. The thermodynamic stability of the black holes has been analyzed by utilizing the canonical and grand canonical ensembles and noting the signature of the black hole heat capacity and Gibbs free energy of the black holes. The points of type-1, type-2, and Hawking–Page phase transitions and the ranges at which the black holes are locally or globally stable have been determined. The geometrical thermodynamics of the black holes has been studied by use of different thermodynamic metrics, and the results of different approaches have been compared.


2019 ◽  
Vol 489 (4) ◽  
pp. 5037-5045 ◽  
Author(s):  
M Bulla

ABSTRACT We present possis, a time-dependent three-dimensional Monte Carlo code for modelling radiation transport in supernovae and kilonovae. The code incorporates wavelength- and time-dependent opacities, and predicts viewing-angle dependent spectra, light curves, and polarization for both idealized and hydrodynamical explosion models. We apply the code to a kilonova model with two distinct ejecta components, one including lanthanide elements with relatively high opacities and the other devoid of lanthanides and characterized by lower opacities. We find that a model with total ejecta mass $M_\mathrm{ej}=0.04\, \mathrm{M}_\odot$ and half-opening angle of the lanthanide-rich component Φ = 30° provides a good match to GW 170817/AT 2017gfo for orientations near the polar axis (i.e. for a system viewed close to face-on). We then show how crucial is the use of self-consistent multidimensional models in place of combining one-dimensional models to infer important parameters, such as the ejecta masses. We finally explore the impact of Mej and Φ on the synthetic observables and highlight how the relatively fast computation times of possis make it well-suited to perform parameter-space studies and extract key properties of supernovae and kilonovae. Spectra calculated with possis in this and future studies will be made publicly available.


1999 ◽  
Vol 08 (02) ◽  
pp. 251-270 ◽  
Author(s):  
JAMES M. GELB ◽  
KAUNDINYA S. GOPINATH ◽  
DALLAS C. KENNEDY

Paralleling a previous paper, we examine single- and many-body states of relativistic electrons in an intense, rotating magnetic dipole field. Single-body orbitals are derived semiclassically and then applied to the many-body case via the Thomas-Fermi approximation. The many-body case is reminiscent of the quantum Hall state. Electrons in a realistic neutron star crust are considered with both fixed density profiles and constant Fermi energy. In the first case, applicable to young neutron star crusts, the varying magnetic field and relativistic Coriolis correction lead to a varying Fermi energy and macroscopic currents. In the second, relevant to older crusts, the electron density is redistributed by the magnetic field.


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