Hints of FLRW breakdown from supernovae

Krishnan, Chethan; Mohayaee, Roya; Colgáin, Eoin Ó; Sheikh-Jabbari, M. M.; Yin, Lu

doi:10.1103/physrevd.105.063514

Cited by 72 publications

(56 citation statements)

References 91 publications

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“…The catalyst for the ongoing debate appears to be so far unexplained differences between the early and the late-time measurements of the Hubble constant [27]. As a result, an increasing number of cosmologists are reconsidering the current cosmological paradigm and even question the FRW models and the Cosmological Principle itself [28][29][30][31][32][33]. Persistent reports of anomalous dipolar anisotropies in the number counts of distant radio-sources have added to this debate [34][35][36][37][38][39][40][41][42][43][44][45][46][47].…”

Section: On the Choice Of Framesmentioning

confidence: 99%

The deceleration parameter in ‘tilted’ universes: generalising the Friedmann background

Tsagas

2022

Eur. Phys. J. C

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Large-scale bulk peculiar motions introduce a characteristic length scale, inside which the local kinematics are dominated by peculiar-velocity perturbations rather than by the background Hubble expansion. Regions smaller than the aforementioned critical length, which typically varies between few hundred and several hundred Mpc, can be heavily “contaminated” by the observers’ relative motion. For example, at the critical length – hereafter referred to as the “transition scale”, the sign of the locally measured deceleration parameter can change from positive to negative, while the surrounding universe is still decelerating globally. Overall, distant observers can assign very different values to their local deceleration parameters, entirely because of their relative motion. In practice, this suggests that information selected from regions inside and close to the transition scale hold only locally and they should not be readily extrapolated to the global universe. We show that this principle applies to essentially all Friedmann backgrounds, irrespective of their equation of state and spatial curvature. Put another way, the transition scale and the related effects are generic to linear peculiar-velocity perturbations. This study generalises previous work applied, primarily for reasons of mathematical simplicity, to a perturbed Einstein–de Sitter universe.

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Section: On the Choice Of Framesmentioning

confidence: 99%

The deceleration parameter in ‘tilted’ universes: generalising the Friedmann background

Tsagas

2022

Eur. Phys. J. C

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“…The second approach has been pursued by computing, for example, the fractal dimension in both two (Alonso et al 2015;Gonçalves et al 2018) and three (Scrimgeour et al 2012) dimensions using galaxy catalogs, showing a good agreement with the standard model. Isotropy has been tested using the CMB (Akrami et al 2014), supernovae (Sun & Wang 2018;Zhao et al 2019;Krishnan et al 2021), compact radio sources (Jackson 2012), quasars (Hirata 2009;Siewert et al 2020;Secrest et al 2020), galaxies (Nadolny et al 2021) and clusters of galaxies (Migkas et al 2020(Migkas et al , 2021. 1 Here, we assume isotropy and test the hypothesis of homogeneity around us using the method proposed in Valkenburg et al (2014), that is, we test the validity of the Copernican principle.…”

Section: Introductionmentioning

confidence: 99%

The Copernican principle in light of the latest cosmological data

Camarena

Marra

Sakr

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We pursue a program to confront observations with inhomogeneous extensions of the FLRW metric. The main idea is to test the Copernican principle rather than assuming it a priori. We consider the ΛCDM model endowed with a spherical ΛLTB inhomogeneity around us, that is, we assume isotropy and test the hypothesis of homogeneity. We confront the ΛLTB model with the latest available data from CMB, BAO, type Ia supernovae, local H0, cosmic chronometers, Compton y-distortion and kinetic Sunyaev-Zeldovich effect. We find that these data can constrain tightly this extra inhomogeneity, almost to the cosmic variance level: on scales ≳ 100 Mpc structures can have a small non-Copernican effective contrast of just δL ∼ 0.01. Furthermore, the constraints on the standard ΛCDM parameters are not weakened after marginalizing over the parameters that model the local structure, to which we assign ignorance priors. In other words, dropping the Copernican principle assumption does not imply worse constraints on the cosmological parameters. This positive result confirms that the present and future data can be meaningfully analyzed within the framework of inhomogeneous cosmology.

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“…Assuming that the TDCOSMO and SLACS galaxies are derived from the same parent population they measured H0 = 67.4 +4.1 −3.2 from the joint hierarchical analysis of the TDCOSMO+SLACS sample so we see that the result of the MOG theory is consistent with their reported results. Of course, this difference in the values reported of Birrer et al (2020) may be due to that the H0LiCOW could be hiding a correlation with the CMB dipole direction as is disccused in Krishnan et al (2021). They presented the cordinates of lenses on the celestial sphere from H0LiCOW and declination and their value of H0.…”

Section: Joint Analysismentioning

confidence: 95%

MOG cosmology without dark matter and the cosmological constant

Davari,

Rahvar

2021

Preprint

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In this work, we investigate the MOdified Gravity (MOG) theory for dynamics of the universe and compare the results with the ΛCDM cosmology. We study the background cosmological properties of the MOG model and structure formation at the linear perturbation level. We compare the two models with the currently available cosmological data by using statistical Bayesian analyses. After obtaining updated constraints on the free parameters, we use some methods of model selection to assist in choosing the more consistent model such as the reduced chi-squared (χ 2 red ) and a number of the basic information criteria such as the Akaike Information Criterion (AIC), the Bayes factor or Bayesian Information Criterion (BIC), and Deviance Information Criterion (DIC). MOG model appears to be consistent with the ΛCDM model by the results of χ 2 red and DIC for an overall statistical analysis using the background data and the linear growth of structure formation.

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Hints of FLRW breakdown from supernovae

Cited by 72 publications

References 91 publications

The deceleration parameter in ‘tilted’ universes: generalising the Friedmann background

The deceleration parameter in ‘tilted’ universes: generalising the Friedmann background

The Copernican principle in light of the latest cosmological data

MOG cosmology without dark matter and the cosmological constant

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