scholarly journals MONTE-CARLO SIMULATION OF NEUTRON STAR ORBITS IN THE GALAXY

2015 ◽  
Vol 30 (2) ◽  
pp. 583-584
Author(s):  
ALI TAANI
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Neutron Star ◽  
The Galaxy

scholarly journals Impact of accretion on the statistics of neutron star masses

2012 ◽  
Vol 8 (S290) ◽  
pp. 195-196
Author(s):  
Z. Cheng ◽  
A. Taani ◽  
Y. H. Zhao
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Neutron Star ◽  
Neutron Stars ◽  
Binary Systems ◽  
Gaussian Function ◽  
Recycling Process ◽  
Mass Distributions ◽  
Spin Period ◽  
Boot Strap

AbstractWe have collected the parameter of 38 neutron stars (NSs) in binary systems with spin periods and measured masses. By adopting the Boot-strap method, we reproduced the procedure of mass calculated for each system separately, to determine the truly mass distribution of the NS that obtained from observation. We also applied the Monte-Carlo simulation and introduce the characteristic spin period 20 ms, in order to distinguish between millisecond pulsars (MSPs) and less recycled pulsars. The mass distributions of MSPs and the less recycled pulsars could be fitted by a Gaussian function as 1.45±0.42 M⊙ and 1.31±0.17 M⊙ (with 1σ) respectively. As such, the MSP masses are heavier than those in less recycled systems by factor of ~ 0.13M⊙, since the accretion effect during the recycling process.

scholarly journals Beaming Due to Comptonisation in X-ray Pulsars

2000 ◽  
Vol 177 ◽  
pp. 435-436
Author(s):  
D.K. Galloway ◽  
K. Wu
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Neutron Star ◽  
X Ray ◽  
Beam Patterns

AbstractComptonisation may play an important role in determining beam patterns and hence pulse profiles in X-ray pulsars. We describe a Monte Carlo simulation used to investigate the spectra and pulse profiles emitted by two semi-infinite homogeneous cyclindrical accretion columns diametrically located on the surface of a ‘canonical’ neutron star.

MONTE CARLO SIMULATION OF NEUTRON STAR MASSES

2013 ◽  
Vol 23 ◽  
pp. 157-160
Author(s):  
ZHENG CHENG ◽  
CHENGMIN ZHANG ◽  
ALI TAANI
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Neutron Star ◽  
Confidence Level ◽  
White Dwarfs ◽  
Binary Systems ◽  
The Other ◽  
Radio Pulsars ◽  
Millisecond Pulsars ◽  
Spin Period

We perform a Monte Carlo simulation to investigate the distribution and evolution of 66 mass measured pulsars. We get the best fits to the distribution at 1.35 ± 0.27M⨀ (1σ confidence level). In addition, we notice bimodal distributions in 1.34 ± 0.15M⨀ and 1.48 ± 0.53M⨀, this can be led to the idea that radio pulsars in binary systems have recycled. Thus we divide the data according to the characteristic spin period into two groups, millisecond pulsars (MSPs), P Spin ≤ 20 ms and less recycled pulsars P Spin ≥ 20 ms , respectively. We show that the distributions of MSPs at 1.42 ± 0.36M⨀, and 1.32 ± 0.18M⨀ for less recycled pulsars. As such, the mass of MSPs are heavier than those in less recycled pulsars by ~ 0.1M⨀, since they accreting material from their companions. On the other hand, the formation of heavier pulsars from the accretion induced collapse of accreting white dwarfs, must be invoked.

Temporal dispersion of the emergence of intelligence: an inter-arrival time analysis

2011 ◽  
Vol 10 (2) ◽  
pp. 131-135 ◽  
Author(s):  
Thomas W. Hair
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Arrival Time ◽  
Time Analysis ◽  
Arrival Times ◽  
The Galaxy ◽  
Sphere Of Influence ◽  
The Impact ◽  
Temporal Dispersion

AbstractMany reasons for why extraterrestrial intelligences might avoid communications with our civilization have been proposed. One possible scenario is that all civilizations follow the lead of some particularly distinguished civilization. This paper will examine the impact the first successful civilization could have on all other subsequent civilizations within its sphere of influence and the ramifications of this as it relates to the Fermi Paradox. Monte Carlo simulation is used to map the inter-arrival times of early civilizations and to highlight the immense epochs of time that the earliest civilizations could have had the Galaxy to themselves.

scholarly journals Identifying birth places of high-velocity stars

2018 ◽  
pp. 211-222
Author(s):  
V. Hambaryan ◽  
R. Neuh¨auser
Keyword(s):  
Monte Carlo ◽  
Neutron Star ◽  
High Velocity ◽  
Covariance Matrices ◽  
High Quality ◽  
Stellar Cluster ◽  
The Past ◽  
The Galaxy ◽  
Astrometric Data ◽  
Gaia Dr2

We searched for the high-velocity and isolated neutron stars that encountered in the past with a stellar cluster/association closer than 20 pc. We took about 830000 stars with the high-quality astrometry and radial velocities from the Gaia DR2 catalogue and empirically selected about 560 high-velocity stars. We used a full gravitational potential of the Galaxy to calculate the motion of a stellar cluster/association and a candidate of high-velocity star from their current positions to the proximity epoch. For these calculations we used a numerical integration in rectangular, Galactocentric coordinates. We used a covariance matrices of the astrometric data for each star to estimate the accuracy of the obtained proximity distance and epoch. For this aim we used a Monte Carlo method, replaced each star with 10 000 of its simulations and studied the distribution of their individual close passages near a stellar cluster/association. In addition, we investigated a neutron star/runaway star pairs very likely both ejected from binary system during supernova event.

Electron Scattering in Solids

1990 ◽  
Vol 48 (2) ◽  
pp. 4-5
Author(s):  
Ryuichi Shimizu ◽  
Ze-Jun Ding
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Angular Distribution ◽  
Elastic Scattering ◽  
Electron Scattering ◽  
Cross Sections ◽  
Expansion Method ◽  
Electron Excitation ◽  
Partial Wave Expansion ◽  
Backscattered Electrons

Monte Carlo simulation has been becoming most powerful tool to describe the electron scattering in solids, leading to more comprehensive understanding of the complicated mechanism of generation of various types of signals for microbeam analysis.The present paper proposes a practical model for the Monte Carlo simulation of scattering processes of a penetrating electron and the generation of the slow secondaries in solids. The model is based on the combined use of Gryzinski’s inner-shell electron excitation function and the dielectric function for taking into account the valence electron contribution in inelastic scattering processes, while the cross-sections derived by partial wave expansion method are used for describing elastic scattering processes. An improvement of the use of this elastic scattering cross-section can be seen in the success to describe the anisotropy of angular distribution of elastically backscattered electrons from Au in low energy region, shown in Fig.l. Fig.l(a) shows the elastic cross-sections of 600 eV electron for single Au-atom, clearly indicating that the angular distribution is no more smooth as expected from Rutherford scattering formula, but has the socalled lobes appearing at the large scattering angle.

Determination of Stoichiometry of GaAs Component in (Gaas)Ge Epitaxially Grown Thin Films by Electron Microprobe X-Ray Analysis

1990 ◽  
Vol 48 (2) ◽  
pp. 264-265
Author(s):  
D. R. Liu ◽  
S. S. Shinozaki ◽  
R. J. Baird
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Compound Semiconductors ◽  
Energy Dispersive Analysis ◽  
X Ray ◽  
Metastable Alloys ◽  
Lower Voltage

The epitaxially grown (GaAs)Ge thin film has been arousing much interest because it is one of metastable alloys of III-V compound semiconductors with germanium and a possible candidate in optoelectronic applications. It is important to be able to accurately determine the composition of the film, particularly whether or not the GaAs component is in stoichiometry, but x-ray energy dispersive analysis (EDS) cannot meet this need. The thickness of the film is usually about 0.5-1.5 μm. If Kα peaks are used for quantification, the accelerating voltage must be more than 10 kV in order for these peaks to be excited. Under this voltage, the generation depth of x-ray photons approaches 1 μm, as evidenced by a Monte Carlo simulation and actual x-ray intensity measurement as discussed below. If a lower voltage is used to reduce the generation depth, their L peaks have to be used. But these L peaks actually are merged as one big hump simply because the atomic numbers of these three elements are relatively small and close together, and the EDS energy resolution is limited.

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