An alternative approach to modelling a cosmic void and its effect on the cosmic microwave background

Kim, Do Young; Lasenby, A.; Hobson, M.

doi:10.1093/mnras/stz1979

Cited by 11 publications

(6 citation statements)

References 38 publications

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“…The spherical void model we work with is qualitatively analogous to earlier models [72][73][74][75]. As in these models, we obtain qualitatively analogous results that depict the expected Fig.…”

Section: Discussion and Final Remarkssupporting

confidence: 82%

“…While numerical relativity techniques have already been applied in a cosmological context beyond spherical symmetry [62][63][64][65][66][67], most relativistic numerical studies on cosmic voids still rely on metric-based techniques involving the Misner-Sharp mass function, and thus their validity is restricted to spherical symmetry [68][69][70][71]. In particular, four relevant studies that specifically examine general relativistic void dynamics for spherical symmetry preceding our study are [72][73][74][75].…”

Section: Introductionmentioning

confidence: 99%

“…In order to deal with the general relativistic dynamics for this energy-momentum tensor, we do not resort to the traditional metric based methods of [72][73][74][75], but consider the system of first order partial differential equations (PDEs) provided by the "fluid-flow" (or "1 + 3") representation of Einstein's equations [76][77][78] in terms of evolution equations and constraints for the covariant quantities associated with the CDM comoving 4-velocity. These covariant variables are (i) kinematic: expansion scalar, 4-acceleration, shear tensor and relative velocity, all computed from the CDM frame; (ii) source terms: the total energy density, pressure and energy flux that arise from the relative velocity and (iii) the electric Weyl tensor.…”

Section: Introductionmentioning

confidence: 99%

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Non-comoving baryons and cold dark matter in cosmic voids

2019

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We examine the fully relativistic evolution of cosmic voids constituted by baryons and cold dark matter (CDM), represented by two non-comoving dust sources in a ΛCDM background. For this purpose, we consider numerical solutions of Einstein's field equations in a fluid-flow representation adapted to spherical symmetry and multiple components. We present a simple example that explores the frame-dependence of the local expansion and the Hubble flow for this mixture of two dusts, revealing that the relative velocity between the sources yields a significantly different evolution in comparison with that of the two sources in a common 4-velocity (which reduces to a Lemaître-Tolman-Bondi model). In particular, significant modifications arise for the density contrast depth and void size, as well as in the amplitude of the surrounding over-densities. We show that an adequate model of a frame-dependent evolution that incorporates initial conditions from peculiar velocities and large-scale density contrast observations may contribute to understand the discrepancy between the local value of H 0 and that inferred from the CMB.

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Section: Discussion and Final Remarkssupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Non-comoving baryons and cold dark matter in cosmic voids

2019

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“…Indeed, using ρ = N/V and V /V = Θ, this equation can be re-written as Ṅ = −ΓN, which is a typical decay law of exponential (or nuclear) decay. The spatial component of (43) allows us to evaluate the acceleration A since…”

Section: E Dark Matter Physicsmentioning

confidence: 99%

“…These methods are however constrained by the requirement of being metric based. Recently, tetra-based methods have been developed as an alternative to LTB models, [43]. The wellestablished semi-tetrad approach of the hydrodynamical 1 + 3 covariant methodology has an intuitive fluid flow interpretation, [18], and when taken to have local rotational symmetry (LRS) or silence (vanishing magnetic Weyl and pressure gradients) offers a generalisation to th LTB models in certain limits [44,45].…”

Section: Introductionmentioning

confidence: 99%

Imprints of decaying dark matter on cosmic voids

Lester,

Bolejko

2021

Preprint

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The Standard Cosmological Model assumes that more than 85% of matter is in the form of collisionless and pressureless dark matter. Unstable decaying dark matter has been proposed in the literature as an extension to the standard cold dark matter model. In this paper we investigate a scenario when dark matter decays and the resultant particle moves with respect to the dark matter. A covariant hydrodynamical model is developed in which the decay is modeled by the transfer of energy-momentum between two dark dust fluid components. We parameterise the model in terms of the decay rate Γ and injection velocity vi of the resultant dark matter particles. We apply the framework to study the evolution of cosmic voids which are environments with low content of baryonic matter. Thus, unlike baryon-rich environments, voids provide an opportunity to measure dark matter signals that are less contaminated by complex baryonic processes. We find that the growth of S-type voids is modified by the dark matter decay, leading to imprints at the present day. This paper serves as a proof-of-concept that cosmic voids can be used to study dark mater physics. We argue that future cosmological observations of voids should focus on signs of reported features to either confirm or rule out the decaying dark matter scenario. Lack of presence of reported features could put constraints of the decay of dark matter in terms of Γ > H −1 0 and vi < 10 km/s.

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