Constraints on modified gravity models from white dwarfs

Banerjee, Srimanta; Shankar, Swapnil; Singh, Tejinder P.

doi:10.1088/1475-7516/2017/10/004

Cited by 72 publications

(63 citation statements)

References 58 publications

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“…They argued that if α > 0, it resulted in sub-Chandrasekhar limiting mass white dwarfs and while for α < 0, it resulted in super-Chandrasekhar white dwarfs. Later appropriate constraints were put in the parameter space, restricted by the observations of various models of f (R) gravity [34]. Eventually f (R, T ) = R + 2λT model was used to describe similar physics of the white dwarfs [10].…”

Section: Introductionmentioning

confidence: 99%

Modified Einstein's gravity to probe the sub- and super-Chandrasekhar limiting mass white dwarfs: a new perspective to unify under- and over-luminous type Ia supernovae

Kalita

Mukhopadhyay

2018

J. Cosmol. Astropart. Phys.

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Type Ia supernovae (SNeIa), used as one of the standard candles in astrophysics, are believed to form when the mass of the white dwarf approaches Chandrasekhar mass limit. However, observations in last few decades detected some peculiar SNeIa, which are predicted to be originating from white dwarfs of mass much less than the Chandrasekhar mass limit or much higher than it. Although the unification of these two sub-classes of SNeIa was attempted earlier by our group, in this work, we, for the first time, explain this phenomenon in terms of just one property of the white dwarf which is its central density. Thereby we do not vary the fundamental parameters of the underlying gravity model in the contrary to the earlier attempt. We effectively consider higher order corrections to the Starobinsky-f (R) gravity model to reveal the unification. We show that the limiting mass of a white dwarf is ∼ M ⊙ for central density ρ c ∼ 1.4 × 10 8 g/cc, while it is ∼ 2.8M ⊙ for ρ c ∼ 1.6 × 10 10 g/cc under the same model parameters. We further confirm that these models are viable with respect to the solar system test. This perhaps enlightens very strongly the long standing puzzle lying with the predicted variation of progenitor mass in SNeIa.

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Section: Introductionmentioning

confidence: 99%

Modified Einstein's gravity to probe the sub- and super-Chandrasekhar limiting mass white dwarfs: a new perspective to unify under- and over-luminous type Ia supernovae

Kalita

Mukhopadhyay

2018

J. Cosmol. Astropart. Phys.

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“…The theory is equivalent to Einstein's GR in vacuum but differs from it within matter. Since its introduction, various aspects of EiBI gravity have been studied by many researchers in the recent past, including black holes [47,[51][52][53][54][55][56][57][58][59][60], wormholes [61][62][63][64], compact stars [65][66][67][68][69], cosmological aspects [47,[70][71][72][73][74][75][76][77][78][79][80], astrophysical aspects [81][82][83], gravitational collapse [84,85], gravitational waves [86,87], implications in nongravitational contexts like particle physics [88] etc. See [89] for a recent review on various studies in EiBI gravity.…”

Section: Introductionmentioning

confidence: 99%

Wormholes with nonexotic matter in Born-Infeld gravity

Shaikh

2018

Phys. Rev. D

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We show that, in contrast to general relativity, in Eddington-inspired Born-Infeld gravity (EiBI), a violation of the null convergence condition does not necessarily lead to a violation of the null energy condition, by establishing a relationship between them. This serves as a motivation for finding wormhole solutions which can be supported by nonexotic matter in this gravity theory. We then obtain exact solutions of the field equations in EiBI gravity coupled to arbitrary nonlinear electrodynamics and anisotropic fluids. Depending on the signs and values of different parameters, the general solutions can represent both black holes and wormholes. In this work, we analyze the wormhole solutions. These wormholes are supported by nonexotic matter, i.e., matter satisfying all the energy conditions. As special cases of our general solutions, we work out several specific examples by considering Maxwell, power-law, Born-Infeld electrodynamics models and a particular form of an anisotropic fluid. * rajibul.shaikh@tifr.res.in

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“…With the purpose of probing this scenario different kind of compact astrophysical objects were chosen. For instance, in work [18] the red and brown dwarfs were used as probes for the modified gravity theories through impact on the mass-radius relation, the Chandrasekhar mass limit and the mass-radius relation for the WDs were used in works [19,20] in order to obtain independent constraints on the Vainshtein breaking parameter. Similar work [17] was devoted to the study of relativistic objects such as WDs and neutron stars in which it was shown the importance of post-Newtonian corrections in equilibrium equation for WDs while calculating macroscopic characteristics in the frame of the theory of modified gravity.…”

Section: Introductionmentioning

confidence: 99%

White dwarfs as a probe of dark energy

2020

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We investigate the radial density distribution of the dynamical dark energy inside the white dwarfs (WDs) and its possible impact on their intrinsic structure. The minimally-coupled dark energy with barotropic equation of state which has three free parameters (density, equation of state and effective sound speed) is used. We analyse how such dark energy affects the mass-radius relation for the WDs because of its contribution to the joint gravitational potential of the system. For this we use Chandrasekhar model of the WDs, where model parameters are the parameter of the chemical composition and the relativistic parameter. To evaluate the dark energy distribution inside a WD we solve the conservation equation in the spherical static metric. Obtained distribution is used to find the parameters of dark energy for which the deviation from the Chandrasekhar model massradius relation become non-negligible. We conclude also, that the absence of observational evidence for existence of WDs with untypical intrinsic structure (mass-radius relation) gives us lower limit for the value of effective sound speed of dark energy c 2 s 10 −4 (in units of speed of light).

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Constraints on modified gravity models from white dwarfs

Cited by 72 publications

References 58 publications

Modified Einstein's gravity to probe the sub- and super-Chandrasekhar limiting mass white dwarfs: a new perspective to unify under- and over-luminous type Ia supernovae

Modified Einstein's gravity to probe the sub- and super-Chandrasekhar limiting mass white dwarfs: a new perspective to unify under- and over-luminous type Ia supernovae

Wormholes with nonexotic matter in Born-Infeld gravity

White dwarfs as a probe of dark energy

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