Comparison between hemisphere comparison method and dipole-fitting method in tracing the anisotropic expansion of the Universe use the Union2 data set

Chang, Zhe; Lin, Hai-Nan

doi:10.1093/mnras/stu2349

Cited by 38 publications

(21 citation statements)

References 36 publications

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“…From Fig. 5, we find that the HC preferred direction in this paper is the deviation from that of the Pantheon sample and the SPARC galaxies sample, but it is generally consistent with those in the Union2 sample (Antoniou & Perivolaropoulos 2010;Cai & Tuo 2012;Chang & Lin 2015), the Union2.1 sample (Sun & Wang 2019;Lin et al 2016a), the Constitution sample (Sun & Wang 2019;Kalus et al 2013), and the JLA sample (Deng & Wei 2018b). Overall, the distribution of the HC preferred direction obtained from a different sample is diffuse.…”

Section: The Hc Methods and Resultssupporting

confidence: 74%

Testing cosmic anisotropy with Pantheon sample and quasars at high redshifts

Wang

2020

A&A

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In this paper, we investigate the cosmic anisotropy from the SN-Q sample, consisting of the Pantheon sample and quasars, by employing the hemisphere comparison (HC) method and the dipole fitting (DF) method. Compared to the Pantheon sample, the new sample has a larger redshift range, a more homogeneous distribution, and a larger sample size. For the HC method, we find that the maximum anisotropy level is ALmax = 0.142 ± 0.026 in the direction (l, b) = (316.08°−129.48+27.41, 4.53°−64.06+26.29). The magnitude of anisotropy is A = (−8.46−5.51+4.34) × 10−4 and the corresponding preferred direction points toward (l, b) = (29.31°−30.54+30.59, 71.40°−9.72+9.79) for the quasar sample from the DF method. The combined SN and quasar sample is consistent with the isotropy hypothesis. The distribution of the dataset might impact the preferred direction from the dipole results. The result is weakly dependent on the redshift from the redshift tomography analysis. There is no evidence of cosmic anisotropy in the SN-Q sample. Though some results obtained from the quasar sample are not consistent with the standard cosmological model, we still do not find any distinct evidence of cosmic anisotropy in the SN-Q sample.

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Section: The Hc Methods and Resultssupporting

confidence: 74%

Testing cosmic anisotropy with Pantheon sample and quasars at high redshifts

Wang

2020

A&A

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“…Moreover, they give different values of dipole magnitude which is interesting to note. The dipole magnitude obtained using DMFDM method (d 1 = (1.4 ± 0.8) × ×10 −3 ) is close to previous studies of [17,59,62] as it has been mentioned in DMFDM method section. However, the dipole magnitude obtained using DMFLD method (d 2 = (0.026 ± 0.014)) is different from the value obtained using DMFDM method and also previous studies.…”

Section: Discussionsupporting

confidence: 88%

“…[62] have applied this method to investigate dipolar asymmetry of the Universe. [17] have made a comprehensive comparison between the HC method and the DF method using the Union2 dataset.…”

Section: Dipole-fitting (Df) Methodsmentioning

confidence: 99%

Searching for a cosmological preferred axis in complicated class of cosmological models: case study f (R, T ) model

Salehi

Aftabi

2016

J. High Energ. Phys.

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Recent astronomical observations show that the universe may be anisotropic on large scales. The Union2 SnIa data hint that the universe has a preferred direction. If such a cosmological privileged axis indeed exists, one has to consider an anisotropic expanding Universe instead of the isotropic cosmological model. In this paper, we present a detailed analysis of the dark energy dipole in f (R, T ) = f 1 (R) + f 2 (T ) Cosmological Model using three types of dipole fit (DF) method which are (I) dipole + monopole fitting for distance modulus (DMFDM), (II) dipole + monopole fitting for luminosity distance (DMFLD) and (III) general dipole fitting for luminosity distance (GDFLD). We have found the maximum anisotropic deviation direction for (DMFDM) method as (l, b) = (315

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“…Another worth discussing issue is that whether the maximum anisotropy level from the SPARC dataset is coming from the non-uniform distribution of the data points in sky. In the study of the anisotropy on supernova, it was pointed out that the anisotropy could be originated from the non-uniform distribution of the data points (Chang & Lin 2015;Beltran Jimenez et al 2015). Here, we take a similar investigation for the SPARC dataset.…”

Section: Maximum Anisotropy Direction Of the Sparc Datasetmentioning

confidence: 99%

Searching for a Cosmological Preferred Direction with 147 Rotationally Supported Galaxies

Zhou

Zhao

Chang

2017

ApJ

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It is well known that the Milgrom's MOND (modified Newtonian dynamics) explains well the mass discrepancy problem in galaxy rotation curves. The MOND predicts a universal acceleration scale below which the Newtonian dynamics is invalid yet. The universal acceleration scale we got from the SPARC dataset is g † = 1.02 × 10 −10 m s −2 . Milgrom suggested that the acceleration scale may be a fingerprint of cosmology on local dynamics and related with the Hubble constant g † ∼ cH 0 . In this paper, we use the hemisphere comparison method with the SPARC dataset to investigate the spatial anisotropy on the acceleration scale. We find that the hemisphere of the maximum acceleration scale is in the direction (l, b) = (175.5•+6• −10 • , −6.5 •+8• −3 • ) with g †,max = 1.10 × 10 −10 m s −2 , while the hemisphere of the minimum acceleration scale is in the opposite direction (l, b) = (355.5•+6• −10 • , 6.5•+3• −8 • ) with g †,min = 0.76 × 10 −10 m s −2 . The maximum anisotropy level reaches up to 0.37 ± 0.04. Robust tests present that such a level of anisotropy can't be reproduced by a statistically isotropic data. In addition, we show that the spatial anisotropy on the acceleration scale has little correlation with the non-uniform distribution of the SPARC data points in sky. We also find that the maximum anisotropy direction is close with other cosmological preferred directions, especially the direction of the "Australia dipole" for the fine structure constant.

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Comparison between hemisphere comparison method and dipole-fitting method in tracing the anisotropic expansion of the Universe use the Union2 data set

Cited by 38 publications

References 36 publications

Testing cosmic anisotropy with Pantheon sample and quasars at high redshifts

Testing cosmic anisotropy with Pantheon sample and quasars at high redshifts

Searching for a cosmological preferred axis in complicated class of cosmological models: case study f (R, T ) model

Searching for a Cosmological Preferred Direction with 147 Rotationally Supported Galaxies

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