Damghan University
Astronomical Society of IranIranian Journal of Astronomy and Astrophysics2322-49244320171201Calculation of the relativistic bulk tensor and shear tensor of relativistic accretion flows in the Kerr metric.عنوان20522112210.22128/ijaa.2017.122ENMahboobeMoeenScience department,Faculty member, Kosar University of Bojnord, IranJournal Article20181201In 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.https://ijaa.du.ac.ir/article_122_c850f8252ffbb5a2c5bbc939a691b85f.pdfDamghan University
Astronomical Society of IranIranian Journal of Astronomy and Astrophysics2322-49244320171201Finite temperature correlation function of two dissipative massive scalar ﬁelds: Thermoﬁeld approachعنوان22323012310.22128/ijaa.2017.123ENMarjanJafariDepartment of Physics, Faculty of Science, Imam Khomeini International University, P.O.Box 34148-96818,
Qazvin, IranJournal Article20181216The 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.https://ijaa.du.ac.ir/article_123_f8de2feace3527d44611adc4fc6ff487.pdfDamghan University
Astronomical Society of IranIranian Journal of Astronomy and Astrophysics2322-49244320171201Introducing Stable Real Non-Topological Solitary Wave Solutions in 1+1 Dimensionsعنوان23124412410.22128/ijaa.2017.124ENMohammadMohammadiPhysics Department, Persian Gulf University, Bushehr 75169, Iran.0000-0002-8057-237XAli RezaOlamaeiJahrom University, Jahrom 74135-111, IranJournal Article20181216By 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.https://ijaa.du.ac.ir/article_124_7471a0364c7fc6b178e36236c967ef18.pdfDamghan University
Astronomical Society of IranIranian Journal of Astronomy and Astrophysics2322-49244320171201Multi fluidity and Solitary wave stability in cold quark matter: core of dense astrophysical objectsعنوان24526012510.22128/ijaa.2017.125ENAzamGhaaniDepartment of Physics, Ferdowsi University of Mashhad, 91775-1436 Mashhad, IranParvinEslamiDepartment of Physics, Ferdowsi University of Mashhad, 91775-1436 Mashhad, IranMohsenSarbishaeiDepartment of Physics, Ferdowsi University of Mashhad, 91775-1436 Mashhad, IranKuroshJavidanDepartment of Physics, Ferdowsi University of Mashhad, 91775-1436 Mashhad, Iran0000-0002-7596-4280Journal Article20181224Considering 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).https://ijaa.du.ac.ir/article_125_04ef1add2900a30c735cb4975b69c650.pdfDamghan University
Astronomical Society of IranIranian Journal of Astronomy and Astrophysics2322-49244320171201Oscillations of a Giant Solar Tornadoعنوان26127112610.22128/ijaa.2017.126ENFatemehHashemi-NasabDepartment of Physics, University of Zanjan, P.O. Box 45195-313, Zanjan, IranNedaDadashiPhysics Department, Faculty of Science, University of Zanjan, Zanjan, Iran0000-0001-7881-1688NasibehAlipour-RadDepartment of Physics, University of Zanjan, P.O. Box 45195-313, Zanjan, IranYousefAliAbediniDepartment of Physics, University of Zanjan, P.O. Box 45195-313, Zanjan, IranJournal Article20181224Solar 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.https://ijaa.du.ac.ir/article_126_eaa05200a6d65c33dd1a39e503451a34.pdfDamghan University
Astronomical Society of IranIranian Journal of Astronomy and Astrophysics2322-49244320171201Thermal measurement induced disturbance in the Bose-Hubbard Hamiltonianعنوان27328212910.22128/ijaa.2017.129ENHamedJafarzadehQuchan University of Technology, Quchan, IranHakimehJaghouriDepartment of Physics, Ferdowsi University of Mashhad, 91775-1436, Mashhad, IranJournal Article20190317We 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.https://ijaa.du.ac.ir/article_129_589fb68d43c6d60852ad90eb7755f445.pdf