Reconstructing the metric of the local Universe from number counts observations

Vallejo, Sergio; Romano, Antonio Enea

doi:10.1088/1475-7516/2017/10/023

Cited by 3 publications

(8 citation statements)

References 59 publications

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“…The cosmic metric that is based on ΛLTB solution locally and asymptotically converges to ΛCDM metric provides a framework for studying the effects of inhomogeneities in standard cosmological model. Furthermore, it can play an important role in precise reconstruction of the cosmic metric that is necessary for future data [19].…”

Section: Constraints On Ltb Modelmentioning

confidence: 99%

Cosmological Constraints from Low-Redshift Data

Luković¹,

Haridasu

Vittorio³

2018

Found Phys

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Section: Constraints On Ltb Modelmentioning

confidence: 99%

Cosmological Constraints from Low-Redshift Data

Luković¹,

Haridasu

Vittorio³

2018

Found Phys

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“…Our goal is to find an analytical formula for the luminosity distance in terms of the density contrast δ(z) at low red-shift. In order to derive the formula we take into account the metric reconstruction of the local Universe given in [32]. We follow the same procedure described in sections III and IV of [32] and we expand the curvature function k(r) according to…”

Section: Coordinate Independent Red-shift Expansion Of the Luminosity...mentioning

confidence: 99%

“…In order to derive the formula we take into account the metric reconstruction of the local Universe given in [32]. We follow the same procedure described in sections III and IV of [32] and we expand the curvature function k(r) according to…”

Section: Coordinate Independent Red-shift Expansion Of the Luminosity...mentioning

confidence: 99%

“…( 2.11) and the eqs. (3.1)-(3.2), we can get the low red-shift expansion of the geodesics equations, and by imposing that each coefficient is zero we get the coefficients of the expansion of the solution of the geodesics equations as [32]…”

Section: Jcap03(2020)023mentioning

confidence: 99%

“…This motivates the calculation of low red-shift expansions for the luminosity distance based on using inhomogeneous exact solutions of Einstein's field equations. The cosmological effects of inhomogeneities on different observables have been studied in , and examples include the expansion scalar [31], number counts, [32] and the luminosity distance [18,19,24,33]. In this paper we focus on the effects on the luminosity distance produced by the monopole of local structure modeled by a spherically symmetric solution of Einstein's equations in presence of the cosmological constant.…”

Section: Introductionmentioning

confidence: 99%

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Coordinate independent approach to the calculation of the effects of local structure on the luminosity distance

Vallejo-Peña

Romano

2020

J. Cosmol. Astropart. Phys.

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Local structure can have important effects on luminosity distance observations, which could for example affect the local estimation of the Hubble constant based on low red-shift type Ia supernovae.Using a spherically symmetric exact solution of the Eistein's equations and a more accurate expansion of the solution of the geodesic equations, we improve the low red-shift expansion of the monopole of the luminosity distance in terms of the curvature function. Based on this we derive the coordinate independent low red-shift expansion of the monopole of the luminosity distance in terms of the monopole of the density contrast. The advantage of this approach is that it relates the luminosity distance directly to density observations, without any dependency on the radial coordinate choice.We compute the effects of different inhomogeneities on the luminosity distance, and find that the formulae in terms of the density contrast are in good agreement with numerical calculations, in the non linear regime are more accurate than the results obtained using linear perturbation theory, and are also more accurate than the formulae in terms of the curvature function.

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Hubble trouble or Hubble bubble?

Romano

2018

Int. J. Mod. Phys. D

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The recent analysis of low-redshift supernovae (SN) has increased the apparent tension between the value of H 0 estimated from low and high redshift observations such as the cosmic microwave background (CMB) radiation. At the same time other observations have provided evidence of the existence of local radial inhomogeneities extending in different directions up to a redshift of about 0.07. About 40% of the Cepheids used for SN calibration are directly affected because are located along the directions of these inhomogeneities. We compute with different methods the effects of these inhomogeneities on the low-redshift luminosity and angular diameter distance using an exact solution of the Einstein's equations, linear perturbation theory and a low-redshift expansion. We confirm that at low redshift the dominant effect is the non relativist Doppler redshift correction, which is proportional to the volume averaged density contrast and to the comoving distance from the center. We derive a new simple formula relating directly the luminosity distance to the monopole of the density contrast, which does not involve any metric perturbation. We then use it to develop a new inversion method to reconstruct the monopole of the density field from the deviations of the redshift uncorrected observed luminosity distance respect to the ΛCDM prediction based on cosmological parameters obtained from large scale observations.The inversion method confirms the existence of inhomogeneities whose effects were not previously taken into account because the 2M + + 1 density field maps used to obtain the peculiar velocity 2 for redshift correction were for z ≤ 0.06, which is not a sufficiently large scale to detect the presence of inhomogeneities extending up to z = 0.07. The inhomogeneity does not affect the high redshift luminosity distance because the volume averaged density contrast tends to zero asymptotically, making the value of H CM B 0 obtained from CMB observations insensitive to any local structure. The inversion method can provide a unique tool to reconstruct the density field at high redshift where only SN data is available, and in particular to normalize correctly the density field respect to the average large scale density of the Universe.

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Reconstructing the metric of the local Universe from number counts observations

Cited by 3 publications

References 59 publications

Cosmological Constraints from Low-Redshift Data

Cosmological Constraints from Low-Redshift Data

Coordinate independent approach to the calculation of the effects of local structure on the luminosity distance

Hubble trouble or Hubble bubble?

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