Post-reionization 21-cm power spectrum for bimetric gravity and its detectability with SKA1-mid telescope

Bassi, Ajay; Dinda, Bikash R.; Sen, Anjan A.

doi:10.1007/s12036-023-09980-6

Cited by 2 publications

(2 citation statements)

References 62 publications

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“…Using the non-relativistic approximations, such as k a H (sub-Hubble) and spatial variations like ∂ i Φ and ∇ 2 Φ are much greater than the temporal variations Φ or Φ (quasistatic) in Eqs. ( 28), (29), and (30), one can arrive at the corresponding equation for the Newtonian perturbation theory. For a detailed discussion, see [68].…”

Section: Perturbation Quantities Wrt Dimensionless Variablesmentioning

confidence: 99%

“…Ever since the discovery of the late time cosmic acceleration, an enormous amount of effort has been given to model this phenomenon. The two broad categories of this effort are the notion of the existence of an exotic matter called the dark energy [15][16][17][18][19][20] and the modification of gravity [21][22][23][24][25][26][27][28][29][30][31][32][33]. In the first case, the dark energy is assumed to have large negative pressure which causes the late time cosmic acceleration.…”

Section: Introductionmentioning

confidence: 99%

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Constraints on the speed of sound in the k-essence model of dark energy

Dinda,

Banerjee

2024

Eur. Phys. J. C

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We consider a k-essence scalar field model for the late-time cosmic acceleration in which the sound speed, parametrized as $$c_s$$ c s is constant. We compute the relevant background and perturbation quantities corresponding to the observables like cosmic microwave background, type Ia supernova, cosmic chronometers, baryon acoustic oscillations, and the $$f\sigma _8$$ f σ 8 . We put constraints on the $$c_s^2$$ c s 2 parameter from these observations along with other parameters. We find lower values of $$c_s^2$$ c s 2 which are close to zero are tightly constrained. Particularly, we find mean value of $$\log _\textrm{10} (c_s^2)$$ log 10 ( c s 2 ) to be $$-0.61$$ - 0.61 and $$c_s^2 \le 10^{-3}$$ c s 2 ≤ 10 - 3 is more than 3$$\sigma $$ σ away from this mean value. This means these observations favor a homogeneous dark energy component compared to the clustering one.

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Section: Perturbation Quantities Wrt Dimensionless Variablesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Constraints on the speed of sound in the k-essence model of dark energy

Dinda,

Banerjee

2024

Eur. Phys. J. C

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A comprehensive data-driven odyssey to explore the equation of state of dark energy

Dinda,

Banerjee

2024

Eur. Phys. J. C

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For the first time, we reconstruct the dark energy equation of the state parameter w from the combination of background and perturbation observations, specifically combining the Hubble parameter data from cosmic chronometer observations and the logarithmic growth rate data from the growth rate observations. We do this analysis using posterior Gaussian process regression without considering any specific cosmological model or parametrization. However there are three main assumptions: (I) a flat Friedmann–Lemaître–Robertson–Walker (FLRW) metric is considered for the cosmological background, (II) there is no interaction between dark energy and matter sectors, and (III) for the growth of inhomogeneity, sub-Hubble approximation and linear perturbations are considered. This study is unique in the sense that the reconstruction of w is independent of any derived parameters such as the present values of the matter-energy density parameter and Hubble parameter. From the reconstruction, we look at how the dark energy equation of state evolves between redshifts 0 and 1.5, finding a slight hint of dynamical behavior in dark energy. However, the evidence is not significant. We also find a leaning towards non-phantom behavior over phantom behavior. We observe that the $$\varLambda $$ Λ CDM model $$(w=-1)$$ ( w = - 1 ) nearly touches the lower boundary of the 1$$\sigma $$ σ confidence region in the redshift range $$0.6 \lesssim z \lesssim 0.85.$$ 0.6 ≲ z ≲ 0.85 . However, it comfortably resides within the 2$$\sigma $$ σ confidence region in the whole redshift range under investigation, $$0\le z \le 1.5.$$ 0 ≤ z ≤ 1.5 . Consequently, the non-parametric, model-independent reconstruction of dark energy provides no compelling evidence to deviate from the $$\varLambda $$ Λ CDM model when considering cosmic chronometer and growth rate observations.

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Post-reionization 21-cm power spectrum for bimetric gravity and its detectability with SKA1-mid telescope

Cited by 2 publications

References 62 publications

Constraints on the speed of sound in the k-essence model of dark energy

Constraints on the speed of sound in the k-essence model of dark energy

A comprehensive data-driven odyssey to explore the equation of state of dark energy

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