Cosmology at high redshift -- a probe of fundamental physics

Sailer, Noah; Castorina, Emanuele; Ferraro, Simone; White, Martin

doi:10.48550/arxiv.2106.09713

Cited by 21 publications

(65 citation statements)

References 151 publications

(252 reference statements)

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“…The information on the cosmology at high redshift (2 < z < 6) by future 21-cm and other surveys will be also important. Especially, the expansion history of the universe at high redshift is very important for clarifying the nature of dark energy (see [26] for future prospects, for example).…”

Section: Discussionmentioning

confidence: 99%

Polarization of CMB and possible time dependence of dark energy

Kitazawa¹

2021

Preprint

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Dark energy has been introduced to explain the present accelerating expansion of the universe. In the ΛCDM model, the present standard model of cosmology, dark energy is described as a cosmological constant which is time independent. The possibility of the time dependence of dark energy has been investigated to obtain deeper understanding of it by looking redshit-magnitude relation of type Ia supernova, for example. We investigate the constraints to the time dependence of dark energy with several phenomenological models by fitting their parameters to the redshit-magnitude relation of the Pantheon supernova catalog, and confirm that little time dependence can not be excluded by the goodness-of-fit criterion only. Such a non-trivial time dependence causes different expansion rate in the period of reionization, which affects the low-ℓ polarization power spectrum of CMB. We investigate the possibility to detect the effect in future probe like LiteBIRD, for example. We find that the low-ℓ EE polarization power spectrum is enhanced in general, but it will be difficult to be detected as far as looking the EE polarization power spectrum only because of the limitation by cosmic variance.

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Section: Discussionmentioning

confidence: 99%

Polarization of CMB and possible time dependence of dark energy

Kitazawa¹

2021

Preprint

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“…(20) Figure 4 shows the equation of state as a function of redshift w u (z) up to redshift z = 6 as expected from the Megamapper proposal [14,15], after setting Ω u0 = 0.6911, Ω r0 = 8.97 × 10 −5 [16]. The different lines correspond to ∆N ef f = 0.19 and (−δ = 0.001, 0.01, 0.1, 1) from top to bottom, respectively.…”

Section: Consistency Conditionmentioning

confidence: 92%

More on Emergent Dark Energy from Unparticles

Artymowski,

Ben-Dayan,

Kumar

2021

Preprint

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In a recent paper [1] we suggested the possibility that the present acceleration of the Universe is due to thermodynamical behavior of unparticles. The model is free of scalar fields, modified gravity, coincidence problem, initial conditions problem and possesses interesting distinct predictions regarding the equation of state of Dark Energy, the growth rate and the number of relativistic degrees of freedom at BBN and CMB decoupling. We further suggested that the model can remove some of the Hubble tension. A recent paper mostly considering a different range of parameter space criticized the idea, claiming the model is unstable and does not fit the data [2]. We demonstrate that these claims are due to incorrect use of approximations and initial conditions and that the model stands tall. We further suggest a consistency condition of the model in terms of observables. We then fit publicly available supernovae data to derive the expected Hubble parameter and constrain the parameters of the model.

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“…Much of this information is encoded in the mapping from redshift space to real space. One of the key connection between real space and redshift space is our ability to model and understand the velocity structure of the large scale density field [6].…”

Section: Introductionmentioning

confidence: 99%

Redshift space distortions in Lagrangian space and the linear large scale velocity field of dark matter

Tyhurst¹,

Padmanabhan²,

Pen³

2022

Preprint

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Untangling the connection between redshift space coordinates, a velocity measurement, and three dimensional real space coordinates, is a cosmological problem that is often modeled through a linear understanding of the velocity-position coupling. This linear information is better preserved in the Lagrangian space picture of the matter density field. Through Lagrangian space measurements, we can extract more information and make more accurate estimates of the linear growth rate of the universe. In this paper, we address the linear modelling of matter particle velocities through transfer functions, and in doing so examine to what degree the decrease in correlation with initial conditions may be contaminated by velocity-based nonlinearities. With a thorough analysis of the monopole-quadrupole ratio, we find the best-fit value for the Eulerian velocity dispersion, σp = 378.3 km/s. The covariance of the cosmological linear growth rate f , is estimated in the Eulerian and Lagrangian cases. Comparing Lagrangian and Eulerian, we find that the error in f improves by a factor of 3, without the need for nonlinear velocity dispersion modelling.

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Cosmology at high redshift -- a probe of fundamental physics

Cited by 21 publications

References 151 publications

Polarization of CMB and possible time dependence of dark energy

Polarization of CMB and possible time dependence of dark energy

More on Emergent Dark Energy from Unparticles

Redshift space distortions in Lagrangian space and the linear large scale velocity field of dark matter

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