The mass of the compact object in the X-ray binary her X-1/HZ her

Абубекеров, М. К.; Antokhina, É. A.; Черепащук, А. М.; Shimanskii, V. V.

doi:10.1134/s1063772908050041

Cited by 108 publications

(36 citation statements)

References 24 publications

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“…In our model, we do not prescribe the EOS; rather we apply two step method to examine the possibility of using the anisotropy to obtain spherically symmetric configurations with Buchdahl metric potential. In order to constrain the value of model parameters, we consider analogue objects with similar mass and radii such as LMC X-4 [103], SMC X-1 [83], EXO 1785-248 [81], SAX J1808.4-3658 (SS2) [84], Her X-1 [82], 4U 1538-52 [83], PSR 1937+21 [86], and Cen X-3 [83] to those stars in Buchdahl anisotropic geometry.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic compact stars in the Buchdahl model: A comprehensive study

et al. 2019

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In this article we present a class of relativistic solutions describing spherically symmetric and static anisotropic stars in hydrostatic equilibrium. For this purpose, we consider a particularized metric potential, namely, Buchdahl ansatz [Phys. Rev. D 116, 1027(1959.] which encompasses almost all the known analytic solution to the spherically symmetric, static Einstein field equations(EFEs) with a perfect fluid source, including in particular the Vaidya-Tikekar and Finch-Skea. We here developed the model by considering anisotropic spherically symmetric static general relativistic configuration that plays a significant effect on the structure and properties of stellar objects. We have considered eight different cases for generalized Buchdahl dimensionless parameter K, and analyzed them in an uniform manner. As a result it turns out that all the considered cases are valid at every point in the interior spacetime. In addition to this, we show that the model satisfies all the energy conditions and maintain hydrostatic equilibrium equation. In the frame work of anisotropic hypothesis, we consider analogue objects with similar mass and radii such as LMC X-4, SMC X-1, EXO 1785-248 etc to restrict the model parameter arbitrariness. Also, establishing a relation between pressure and density in the form of P = P (ρ), we demonstrate that EoSs can be approximated to a linear function of density. Despite the simplicity of this model, the obtained results are satisfactory.

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Section: Introductionmentioning

confidence: 99%

Anisotropic compact stars in the Buchdahl model: A comprehensive study

et al. 2019

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“…In this interest, we would like to discuss that our results for λ = 0 of Eqs. (19)-(21), (29)-(31), (35), (39), (55), (57), (58), (61), (66)-(69) approaches to Eqs. 9-11, 28-30, 33, 35, 54, 56, 58, 61, 66-69 of Herrera Ref.…”

Section: Discussionmentioning

confidence: 99%

Complexity factor for anisotropic source in non-minimal coupling metric f(R) gravity

Abbas

Nazar

2018

Eur. Phys. J. C

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In this outline we recognize the idea of complexity factor for static anisotropic selfgravitating source with generalized f (R) metric gravity theory. In present consideration, we express the Einstein field equations, hydrostatic equilibrium equation, the mass function and physical behavior of f (R) model by using some observational data of well known compact stars like 4U 1820 − 30, SAX J1808.4 − 3658 and Her X − 1. We define the scalar functions through the orthogonal splitting of the Reimann-Christofell tensor and then find the vanishing complexity condition for self-gravitating system with the help of these scalars. It has been found that the vanishing condition for the complexity are pressure anisotropy and energy density inhomogeneity must cancel each other. Moreover, we study the momentous results of an astral object for the vanishing of complexity factor. Finally, these solutions reduced to previous investigation about complexity factor in General Relativity by taking λ = 0.

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“…Indeed, recent analysis of non-LTE effects in the formation of the H γ absorption line allows two solutions: q = 0.45 and q = 0.72 (Abubekerov et al 2008). Equation (8) implies that the critical (Ṁ x ) cons decreases for smaller q: for q = 0.45 we obtain (Ṁ x ) cons 5.4 × 10 17 g s −1 .…”

Section: Evidence For the Coronal Mass Ejectionmentioning

confidence: 98%

Continuous monitoring of pulse period variations in Hercules X-1 usingSwift/BAT

Klochkov¹,

Staubert²,

Постнов³

et al. 2009

A&A

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Context. Monitoring of pulse period variations in accreting binary pulsars is an important tool to study the interaction between the magnetosphere of the neutron star and the accretion disk. While the X-ray flux of the brightest X-ray pulsars have been successfully monitored over many years (e.g. with RXTE/ASM, CGRO/BATSE, Swift/BAT), the possibility to monitor their pulse timing properties continuously has so far been very limited. Aims. In our work we show that the Swift/BAT observations can be used to monitor coherent pulsations of bright X-ray sources and use Swift archival data to study one of the most enigmatic X-ray pulsars, Hercules X-1. A quasi-continuous monitoring of the pulse period and the pulse period derivative of an X-ray pulsar, here Her X-1, is achieved over a long time ( 4 yr). We compare our observational results with predictions of accretion theory and use them to test different aspects of the physical model of the system. Methods. In our analysis we use the data accumulated with Swift/BAT starting from the beginning of 2005 (shortly after launch) until the present time. To search for pulsations and for their subsequent analysis we used the count rate measured by the BAT detector in the entire field of view. Results. The slope of the correlation between the locally determined spin-up rate and the X-ray luminosity is measured for Her X-1 and found to be in agreement with predictions of basic accretion torque theory. The observed behaviour of the pulse period together with the previously measured secular decrease of the system's orbital period is discussed in the framework of a model assuming ejection of matter close to the inner boundary of the accretion disk.

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The mass of the compact object in the X-ray binary her X-1/HZ her

Cited by 108 publications

References 24 publications

Anisotropic compact stars in the Buchdahl model: A comprehensive study

Anisotropic compact stars in the Buchdahl model: A comprehensive study

Complexity factor for anisotropic source in non-minimal coupling metric f(R) gravity

Continuous monitoring of pulse period variations in Hercules X-1 usingSwift/BAT

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