Impact of Rastall Gravity on Mass, Radius, and Sound Speed of the Pulsar PSR J0740+6620

Hanafy, W. El

doi:10.3847/1538-4357/ac9410

Cited by 26 publications

(7 citation statements)

References 67 publications

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“…Remarkably, other physical constraints put more restrictive bounds on the compactness in strong anisotropic cases [32][33][34][35]. Same conclusion has been obtained when nonminimal coupling between geometry and matter is considered [26,36,37]. In this sense, it is useful to examine this constraint within the quadratic f (R) gravity as considered in the present study.…”

Section: Equation Of State and Mass-radius Relationsupporting

confidence: 57%

“…In spite of the capability of the model to lower the speed of sound in comparison to the GR or quadratic gravity with positive ϵ cases, it is still above the conjectured conformal upper bound on the maximum sound speed c 2 s = c 2 /3. This result may favor matter-geometry nonminimal coupling scenario to provide better framework for treating that issue as suggested by [26,37,84].…”

Section: Jcap09(2023)038mentioning

confidence: 90%

“…In this case, additional physical constraints are needed to suppress this JCAP09(2023)038 value to physical limit [32][33][34][35]. Similarly, this can be extended to modified gravity when matter-geometry nonminimal coupling is considered [26,36,37].…”

Section: Introductionmentioning

confidence: 99%

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Constraining quadratic f(R) gravity from astrophysical observations of the pulsar J0704+6620

Nashed,

El Hanafy

2023

J. Cosmol. Astropart. Phys.

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We apply quadratic f(R) = R + ϵR 2 field equations, where ϵ has a dimension [L2], to static spherical stellar model. We assume the interior configuration is determined by Krori-Barua ansatz and additionally the fluid is anisotropic. Using the astrophysical measurements of the pulsar PSR J0740+6620 as inferred by NICER and XMM observations, we determine ϵ ≈ ± 3 km2. We show that the model can provide a stable configuration of the pulsar PSR J0740+6620 in both geometrical and physical sectors. We show that the Krori-Barua ansatz within f(R) quadratic gravity provides semi-analytical relations between radial, pr , and tangential, pt , pressures and density ρ which can be expressed as pr ≈ vr 2 (ρ-ρ 1) and pr ≈ vt 2 (ρ-ρ 2), where vr (vt ) is the sound speed in radial (tangential) direction, ρ 1 = ρs (surface density) and ρ 2 are completely determined in terms of the model parameters. These relations are in agreement with the best-fit equations of state as obtained in the present study. We further put the upper limit on the compactness, C = 2GMRs -1 c -2, which satisfies the f(R) modified Buchdahl limit. Remarkably, the quadratic f(R) gravity with negative ϵ naturally restricts the maximum compactness to values lower than Buchdahl limit, unlike the GR or f(R) gravity with positive ϵ where the compactness can arbitrarily approach the black hole limit C → 1. The model predicts a core density a few times the saturation nuclear density ρ nuc = 2.7 × 1014 g/cm3, and a surface density ρs > ρnuc . We provide the mass-radius diagram corresponding to the obtained boundary density which has been shown to be in agreement with other observations.

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Section: Equation Of State and Mass-radius Relationsupporting

confidence: 57%

Section: Jcap09(2023)038mentioning

confidence: 90%

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Constraining quadratic f(R) gravity from astrophysical observations of the pulsar J0704+6620

Nashed,

El Hanafy

2023

J. Cosmol. Astropart. Phys.

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“…Here F h and F g are the hydrostatic and the gravitational forces. We defined the different forces as (Nashed & El Hanafy 2022;El Hanafy 2022):…”

Section: The Adiabatic and Hydrodynamic Equilibrium Conditionsmentioning

confidence: 99%

Analytic charged BHs in f(R) gravity

Nashed

Nojiri

2021

Physics Letters B

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“…of PSR J0740+6620 was studied in Ref. [62]. Considering perfect fluid spheres, the impact of Rastall parameter was investigated in Ref.…”

Section: Introductionmentioning

confidence: 99%

Some medicinal plants with anti -fertility potential used by the tribal people of the District Cooch Behar, West Bengal, India

Bhattacharjee¹

2021

IJERR

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The increase in population is becoming a comprehensive dilemma, causing much pressure alternative medicine for anti-fertility action. Ayurveda and other Indian literature mention the use of plants in various human ailments. India has about more than 45000 plant species and among them several thousand are claimed to possess medicinal properties. Researchers conducted in the last few decades on the plants mentioned in ancient literature or used traditionally for anti-fertility action. This review reveals that some plants and their part used having anti-fertility action, which are helpful for researcher to develop new herbal anti-fertility formulations. In the recent years, interest in drugs of plant origin has been progressively increased. The Koch Rajbangshi people use various wild and cultivated plants as medicine for curing different diseases. They completely or partially depend upon these plants for curing various diseases. The plants are mostly used as first aid treatment in most of the diseases. In almost every village there is a medical man who generally knows the traditional uses of the plants. There are some ritual believes also associated with these medicinal plants or ethnomedicines. A good number of these plants are also included in their daily diet. Above all, the plants have also some market value, thus playing an important socio-economic role among the people of the various tribal people. With the use of modern day medical techniques the traditional health care system is now at the verge of extinction. In the present work, the Researcher tried to document the plants used for the medicinal purposes in the, District Cooch Behar or Koch Bihar of the North Bengal region. To create a database of traditional knowledge and use pattern of some plants with infertility potential by Koch or Rajbangshi people in the region all the plants with its uses are documented in this study.

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Impact of Rastall Gravity on Mass, Radius, and Sound Speed of the Pulsar PSR J0740+6620

Cited by 26 publications

References 67 publications

Constraining quadratic f(R) gravity from astrophysical observations of the pulsar J0704+6620

Constraining quadratic f(R) gravity from astrophysical observations of the pulsar J0704+6620

Analytic charged BHs in f(R) gravity

Some medicinal plants with anti -fertility potential used by the tribal people of the District Cooch Behar, West Bengal, India

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