Revisiting the statistical isotropy of GRB sky distribution

Andrade, Uendert; Bengaly, Carlos A. P.; Alcaniz, J. S.; Capozziello, Salvatore

doi:10.1093/mnras/stz2754

Cited by 23 publications

(12 citation statements)

References 58 publications

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“…Andrade et al [39] tested the sky distribution isotropy of the FERMI-GBM catalogue's 2626 GRBs. The large positional uncertainties in the positions prevented the applied twopoint angular correlation function from detecting any statistical anisotropy, both for the long and short GRBs.…”

Section: Large-scale Distribution and Physical Properties Of Grbsmentioning

confidence: 99%

The Spatial Distribution of Gamma-Ray Bursts with Measured Redshifts from 24 Years of Observation

et al. 2022

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Gamma-ray bursts (GRBs) are the most luminous objects known: they outshine their host galaxies, making them ideal candidates for probing large-scale structure. Our aim is to determine the Spatial Two-Point Correlation Function of the GRBs with spectroscopic redshifts. We used all observations till 4 June 2021, and we also split the data according to the origin of the redshift (afterglow or host galaxy). We analyzed the possible correlation between the GRB redshift and sky position. There is only one region, called the Faraway GRB Patch, where nine distant GRBs shows deviation from the randomness with an ≈1% significance, showing that the sky and the radial component of the GRB distribution could be factorized and both can be determined independently. The GRBs’ cumulative monthly distribution was used to show that it is impossible to synthesize the Sky Exposure Function, even from the perfect observational logs. We estimated the Sky Exposure Function using the Gaussian kernel, and with the radial distribution, it was used for the estimation of the Spatial Two-Point Correlation Function. Monte Carlo simulations were used to determine the Poissonian errors. Our result shows that the current Spatial Two-Point Correlation Function estimations are consistent with zero for the full and the afterglow/host galaxy datasets.

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Section: Large-scale Distribution and Physical Properties Of Grbsmentioning

confidence: 99%

The Spatial Distribution of Gamma-Ray Bursts with Measured Redshifts from 24 Years of Observation

et al. 2022

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“…Previous work has shown no statistically significant violation of isotropy in the observational data of Type Ia Supernova distances [4,5,6] and of gamma-ray bursts [7,8,9]. More stringent tests require the far higher number densities delivered by large galaxy surveys.…”

Section: Introductionmentioning

confidence: 96%

Testing the cosmological principle in the radio sky

Bengaly

Maartens

Randriamiarinarivo

et al. 2019

J. Cosmol. Astropart. Phys.

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The Cosmological Principle states that the Universe is statistically isotropic and homogeneous on large scales. In particular, this implies statistical isotropy in the galaxy distribution, after removal of a dipole anisotropy due to the observer's motion. We test this hypothesis with number count maps from the NVSS radio catalogue. We use a local variance estimator based on patches of different angular radii across the sky and compare the source count variance between and within these patches. In order to assess the statistical significance of our results, we simulate radio maps with the NVSS specifications and mask. We conclude that the NVSS data is consistent with statistical isotropy.

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“…Because GRBs are extremely luminous objects and suitable for exploring the distant universe, many authors have used them to test the cosmological isotropy (Andrade et al 2019;Bernui et al 2008;Li & Lin 2015;Řípa & Shafieloo 2017Řípa & Shafieloo , 2019Tarnopolski 2017). The comoving diameter of the GGR is ≈ 1.2h −1 Gpc when the ΛCDM cosmology is assumed, making it possibly one of the largest structures in the universe.…”

Section: Introductionmentioning

confidence: 99%

“…The so‐called Giant GRB Ring (GGR) is one such example, which is a ring‐like pattern of nine gamma‐ray bursts (GRBs) at redshifts 0.78 < z < 0.86 with an angular diameter of

\approx {40}^{{}^{\circ}}

(Balázs et al 2015; Balázs et al 2018). Because GRBs are extremely luminous objects and suitable for exploring the distant universe, many authors have used them to test the cosmological isotropy (Andrade et al 2019; Bernui et al 2008; Li & Lin 2015; Řípa & Shafieloo 2017, 2019; Tarnopolski 2017). The comoving diameter of the GGR is

\approx 1.2{h}^{-1}\kern0.5em \mathrm{Gpc}

when the ΛCDM cosmology is assumed, making it possibly one of the largest structures in the universe.…”

Section: Introductionmentioning

confidence: 99%

Doubt on the statistical significance of the Giant GRB Ring

Fujii¹

2022

Astron Nachr

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Balázs et al. discovered a gigaparsec‐scale ring‐like cluster of gamma‐ray bursts (GRBs) at redshift z∼0.8$$ z\sim 0.8 $$, the so‐called Giant GRB Ring (GGR), and claimed that the existence of such a gigantic structure challenges the standard cosmological paradigm. We show that the kth nearest neighbor analysis of Balázs et al., by which they estimated the probability of finding by chance a GRB cluster comparable to the GGR to be only 0.05%, has several flaws in the statistical reasoning. After correcting these flaws, the above probability becomes 5–20%, considerably higher than the original estimate and large enough to discard the hypothesis that the GGR has a physical origin. Moreover, this probability is even higher, 60–90%, when using the most recent compilation of GRB data whose redshifts have been measured. We conclude that the GGR is merely a pattern that occurred by chance in the random distribution of GRBs.

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Revisiting the statistical isotropy of GRB sky distribution

Cited by 23 publications

References 58 publications

The Spatial Distribution of Gamma-Ray Bursts with Measured Redshifts from 24 Years of Observation

The Spatial Distribution of Gamma-Ray Bursts with Measured Redshifts from 24 Years of Observation

Testing the cosmological principle in the radio sky

Doubt on the statistical significance of the Giant GRB Ring

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