eng
Damghan University
Astronomical Society of Iran
Iranian Journal of Astronomy and Astrophysics
2322-4924
2383-403X
2017-12-01
4
3
205
221
10.22128/ijaa.2017.122
122
Calculation of the relativistic bulk tensor and shear tensor of relativistic accretion flows in the Kerr metric.
عنوان
Mahboobe Moeen
dr.moeen@kub.ac.ir
1
Science department,Faculty member, Kosar University of Bojnord, Iran
In this paper, we calculate the relativistic bulk tensor and shear tensor of the relativistic accretion ows in the Kerr metric, overall and without any approximation. We obtain the relations of all components of the relativistic bulk and shear tensor in terms of components of four-velocity and its derivatives, Christoffel symbols and metric components in the BLF. Then, these components are derived in the equa-torial plane. To see the behavior of the relativistic bulk tensor and shear tensor in the relativistic accretion disks around the rotating black holes, we introduce a radial form for the radial component of the four-velocity in the LNRF; therefore, all components of the bulk and shear tensor are derived in the BLF. Figures of non-zero components of the bulk tensor and shear tensor are shown for some states. We use the radial model to study the importance and in uence of the relativistic bulk tensor in the accretion disks around the rotating black holes. Also, we see that in some cases bulk tensor may be important and comparable with the shear tensor. Especially, we see that bulk tensor in the inner radii is more important.
http://ijaa.du.ac.ir/article_122_c850f8252ffbb5a2c5bbc939a691b85f.pdf
relativistic viscosity
relativistic bulk tensor
relativistic shear tensor
relativistic shear stress viscosity
black holes accretion disks
relativistic flows
eng
Damghan University
Astronomical Society of Iran
Iranian Journal of Astronomy and Astrophysics
2322-4924
2383-403X
2017-12-01
4
3
223
230
10.22128/ijaa.2017.123
123
Finite temperature correlation function of two dissipative massive scalar ﬁelds: Thermoﬁeld approach
عنوان
Marjan Jafari
1
Department of Physics, Faculty of Science, Imam Khomeini International University, P.O.Box 34148-96818, Qazvin, Iran
The present paper aims at investigating the manner of two dissipative massive scalar ﬁelds. Two massive scalar ﬁelds that interact with a reservoir were considered and a reservoir was modeled by continuum Klein-Gordon ﬁelds. The Lagrangian of the total system was canonically quantized and the dynamics of the system was determined using the Euler-Lagrange equation. Then, the explicit form of the quantum massive scalar ﬁelds in long-time limit were observed. The propagator of the system and correlation functions were calculated at ﬁnite temperature in the thermoﬁeld dynamics formalizem.
http://ijaa.du.ac.ir/article_123_f8de2feace3527d44611adc4fc6ff487.pdf
massive scalar ﬁeld
correlation function
dissipative
thermoﬁeld dynamics
eng
Damghan University
Astronomical Society of Iran
Iranian Journal of Astronomy and Astrophysics
2322-4924
2383-403X
2017-12-01
4
3
231
244
10.22128/ijaa.2017.124
124
Introducing Stable Real Non-Topological Solitary Wave Solutions in 1+1 Dimensions
عنوان
Mohammad mohammadi
physmohammadi@pgu.ac.ir
1
Ali Reza Olamaei
olamaei@jahromu.ac.ir
2
Physics Department, Persian Gulf University, Bushehr 75169, Iran.
Jahrom University, Jahrom 74135-111, Iran
By adding a proper term to the Lagrangian density of a real non-linear KG system with a proposed non-topological unstable solitary wave solution, its stability guaranteed appreciably. This additional term in the new modiﬁed Lagrangian density behaves like a strong internal force which stands against any arbitrary small deformation in the proposed non-topological solitary wave solution.
http://ijaa.du.ac.ir/article_124_7471a0364c7fc6b178e36236c967ef18.pdf
non-linear KG systems
non-topological
solitary wave solutions
stability
soliton
eng
Damghan University
Astronomical Society of Iran
Iranian Journal of Astronomy and Astrophysics
2322-4924
2383-403X
2017-12-01
4
3
245
260
10.22128/ijaa.2017.125
125
Multi fluidity and Solitary wave stability in cold quark matter: core of dense astrophysical objects
عنوان
Azam Ghaani
az.ghaani@stu-mail.um.ac.ir
1
Parvin Eslami
eslami@ferdowsi.um.ac.ir
2
Mohsen Sarbishaei
sarbishei@um.ac.ir
3
Kurosh Javidan
javidan@um.ac.ir
4
Department of Physics, Ferdowsi University of Mashhad, 91775-1436 Mashhad, Iran
Department of Physics, Ferdowsi University of Mashhad, 91775-1436 Mashhad, Iran
Department of Physics, Ferdowsi University of Mashhad, 91775-1436 Mashhad, Iran
Department of Physics, Ferdowsi University of Mashhad, 91775-1436 Mashhad, Iran
Considering the magneto-hydrodynamic equations in a non-relativistic multi uid framework, we study the behavior of small amplitude perturbations in cold quark matter. Magneto-hydrodynamic equations, along with a suitable equation of state for the cold quark matter, are expanded using the reductive perturbation method. It is shown that in small amplitude approximation, such a medium should be considered as a multi- uid system. The result is a nonlinear wave equation which complies with a modied form of the derivative nonlinear Schrodinger equation instead of the KdV equation. Considering the magnetic eld which is supported by the Maxwell's equations, we show that the complete set of equations, create stable solitary waves. An interesting result is the existence of an electric eld component along the direction of magnetic eld which causes a small charge separability in the medium. Properties of this solitonic solution are studied by considering different values for the environmental characters such as background mass density and strength of the magnetic eld (at the scale of compact stars).
http://ijaa.du.ac.ir/article_125_04ef1add2900a30c735cb4975b69c650.pdf
keyword
eng
Damghan University
Astronomical Society of Iran
Iranian Journal of Astronomy and Astrophysics
2322-4924
2383-403X
2017-12-01
4
3
261
271
10.22128/ijaa.2017.126
126
Oscillations of a Giant Solar Tornado
عنوان
Fatemeh Hashemi-Nasab
fatima.hashemi@gmail.com
1
Neda Dadashi
dadashi@znu.ac.ir
2
Nasibeh Alipour-Rad
alipourrad@znu.ac.ir
3
YousefAli Abedini
4
Department of Physics, University of Zanjan, P.O. Box 45195-313, Zanjan, Iran
Physics Department, Faculty of Science, University of Zanjan, Zanjan, Iran
Department of Physics, University of Zanjan, P.O. Box 45195-313, Zanjan, Iran
Department of Physics, University of Zanjan, P.O. Box 45195-313, Zanjan, Iran
Solar magnetic tornadoes are known to be one of the mass and energy transport mechanisms from the lower solar atmosphere into the upper layers of the solar corona. A bright spiral structure with two arms is observed using high-cadence EUV images of 171, 193 and 304 Ǻ channels of Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory (SDO) on 10th of July 2011 for three hours. The structure studied here looks bright in front of dark background emissions. The rotational energy budget of this tornado is estimated using three different approaches. Results showed the rotational energy ranges between 1.95×10<sup>18</sup> erg to 3.36×10<sup>19</sup> erg. After correcting for the solar differential rotation, the oscillatory behaviour of the structure is studied using FFT technique. Results show four different regimes of oscillations: 3-min, 5-6 min, 8-11 min, and 15-17 min. The showed origin of each of these oscillations are discussed.
http://ijaa.du.ac.ir/article_126_eaa05200a6d65c33dd1a39e503451a34.pdf
Sun: Corona
Sun: Tornado
Sun: UV radiation
Sun: Oscillations
eng
Damghan University
Astronomical Society of Iran
Iranian Journal of Astronomy and Astrophysics
2322-4924
2383-403X
2017-12-01
4
3
273
282
10.22128/ijaa.2017.129
129
Thermal measurement induced disturbance in the Bose-Hubbard Hamiltonian
عنوان
Hamed Jafarzadeh
1
Hakimeh Jaghouri
2
Quchan University of Technology, Quchan, Iran
Department of Physics, Ferdowsi University of Mashhad, 91775-1436, Mashhad, Iran
We study measurement induced disturbance (MID) in a qutrit –qutrit system with considering the effect of the external magnetic field, nonlinear and linear coupling constants and temperature. We show that all of these parameters have effective roles in MID. We also investigate the effect of finite external magnetic fields direction as parallel and anti-parallel on MID, and find some interesting results.
http://ijaa.du.ac.ir/article_129_589fb68d43c6d60852ad90eb7755f445.pdf
qutrit
measurement induced disturbance
Bose-Hubbard Hamiltonian