Percent-Level Test of Isotropic Expansion Using Type Ia Supernovae

Soltis, John; Farahi, Arya; Huterer, Dragan; Liberato, C. Michael

doi:10.1103/physrevlett.122.091301

Cited by 37 publications

(32 citation statements)

References 42 publications

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“…Our result for the level of local anisotropy in Pantheon SN Ia is consistent with previous works that find null evidence against assumption of the isotropy (Andrade et al 2018;Zhao et al 2019b), although less stringent compared to global anisotropy constraint found by Soltis et al (2019). Analogously to eq.…”

Section: Anisotropy Considerationssupporting

confidence: 92%

“…On the other side, the large-volume cosmological N-body simulations based on the Planck ΛCDM model, such as e.g. in Skillman et al (2014), can be used to quantify both the effect of cosmic variance and the SN Ia sample selection on H bg 0 value, leading to an even smaller estimate of the expected variance level -Wu & Huterer (2017) found ∼ 0.5% for 0.0233 ≤ z ≤ 0.15 cut (c.f. an earlier work by Wojtak et al (2014)).…”

Section: Distance Ladder Measurementsmentioning

confidence: 99%

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Exploring the evidence for a large local void with supernovae Ia data

Luković

Haridasu

Vittorio

2019

Monthly Notices of the Royal Astronomical Society

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In the present work we utilise the most recent publicly available SN Ia compilations and implement a well formulated cosmological model based on LTB metric in presence of cosmological constant Λ (ΛLTB) to test for signatures of large local inhomogeneities at z ≤ 0.15. Local underdensities in this redshift range have been previously found based on luminosity density data and galaxy number counts. Our main constraints on the possible local void using the Pantheon SN Ia dataset are -redshift size of z size = 0.068 +0.021 −0.030 and density contrast of δΩ 0 /Ω 0 = −10.5 +9.3 −7.4 % in 68% confidence intervals. Investigating the possibility to alleviate the tension between the measurements of present expansion rate H 0 , coming from calibrated local SN Ia and high-z CMB data, we confirm previous findings that large local void alone is a very unlikely explanation for the ∼ 9% disagreement between the two estimates. However, constraints from our SN Ia analysis inside 1σ confidence regions of z size − δΩ 0 /Ω 0 plane allow a void of e.g. z size = 0.075 (320 h 70 −1 Mpc) and δΩ 0 /Ω 0 = −20%. Fitting Pantheon SN Ia from 0.023 < z < 0.15 range, we find a 1.1% shift towards lower H 0 value for ΛLTB model compared to model-independent method with Taylor expanded distance formula. Analysing luminosity density data with ΛLTB model yields constraint on contrast of large isotropic void δΩ 0 /Ω 0 = −51.9 ± 6.3%, which is in ∼ 4σ tension with SN Ia results. More data is necessary to better constrain the local matter density profile and understand the disagreement between SN Ia and luminosity density samples.

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Section: Anisotropy Considerationssupporting

confidence: 92%

Section: Distance Ladder Measurementsmentioning

confidence: 99%

Exploring the evidence for a large local void with supernovae Ia data

Luković

Haridasu

Vittorio

2019

Monthly Notices of the Royal Astronomical Society

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“…It is important to note that the cosmological principle, stating that our universe on large scales is simply homogeneous and isotropic Friedmann-Lemaître-Robertson-Walker (FLRW) spacetime [10], has been the key base of most inflationary models [9]. However, testing the a e-mail: tuan.doquoc@phenikaa-uni.edu.vn (corresponding author) b e-mail: gore@mail.nctu.edu.tw validity of the cosmological principle is not a straightforward task [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Anisotropic power-law inflation for a model of two scalar and two vector fields

Tuan

Kao

2021

Eur. Phys. J. C

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Inspired by an interesting counterexample to the cosmic no-hair conjecture found in a supergravity-motivated model recently, we propose a multi-field extension, in which two scalar fields are allowed to non-minimally couple to two vector fields, respectively. This model is shown to admit an exact Bianchi type I power-law solution. Furthermore, stability analysis based on the dynamical system method is performed to show that this anisotropic solution is indeed stable and attractive if both scalar fields are canonical. Nevertheless, if one of the two scalar fields is phantom then the corresponding anisotropic power-law inflation turns unstable as expected.

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“…Cosmological principle, which states that our universe is just simply homogeneous and isotropic on large scales as described the Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetime, has played a central role in cosmology although it is not straightforward to observationally confirm this principle [1][2][3]. In fact, many theoretical predictions of the so-called cosmic inflation theory [4][5][6][7], which is basically based on the cosmological principle, have been well confirmed by the cosmic microwave background radiations (CMB) observations such as the Wilkinson Microwave Anisotropy Probe satellite (WMAP) [8] as well as the Planck one [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Stable small spatial hairs in a power-law k-inflation model

Tuan

2021

Eur. Phys. J. C

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In this paper, we extend our investigation of the validity of the cosmic no-hair conjecture within non-canonical anisotropic inflation. As a result, we are able to figure out an exact Bianchi type I solution to a power-law k-inflation model in the presence of unusual coupling between scalar and electromagnetic fields as $$-f^2(\phi )F_{\mu \nu }F^{\mu \nu }/4$$ - f 2 ( ϕ ) F μ ν F μ ν / 4 . Furthermore, stability analysis based on the dynamical system method indicates that the obtained solution does admit stable and attractive hairs during an inflationary phase and therefore violates the cosmic no-hair conjecture. Finally, we show that the corresponding tensor-to-scalar ratio of this model turns out to be highly consistent with the observational data of the Planck 2018.

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Percent-Level Test of Isotropic Expansion Using Type Ia Supernovae

Cited by 37 publications

References 42 publications

Exploring the evidence for a large local void with supernovae Ia data

Exploring the evidence for a large local void with supernovae Ia data

Anisotropic power-law inflation for a model of two scalar and two vector fields

Stable small spatial hairs in a power-law k-inflation model

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