Probing the anisotropic expansion from supernovae and GRBs in a model-independent way

Abstract

In this paper, we study the anisotropic expansion of the universe using type Ia supernovae Union 2.1 sample and 116 long gamma-ray bursts. The luminosity distance is expanded with model-independent cosmographic parameters as a function of $z/(1+z)$ directly. Thus the results are independent of cosmology model. We find a dipolar anisotropy in the direction ($l=309.2^{\circ }\pm 15.8^{\circ }$, $b=-8.6^{\circ }\pm 10.5^{\circ }$) in galactic coordinates with a significant evidence $97.29\%$ (more than $2\sigma$). The magnitude is $(1.37\pm 0.57)\times 10^{-3}$ for the dipole, and $(2.6\pm 2.1)\times 10^{-4}$ for the monopole, respectively. This dipolar anisotropy is more significant at low redshift from the redshift tomography analysis. We also test whether this preferred direction is caused by bulk flow motion or dark energy dipolar scalar perturbation. We find that the direction and the amplitude of the bulk flow in our results are approximately consistent with the bulk flow surveys. Therefore, bulk flow motion may be the main reason for the anisotropic expansion at low redshift, but the effect of dipolar distribution dark energy can not be excluded, especially at high redshift.

17 pages, 5 figures, 5 tables, accepted for publication in MNRAS

References in corpus (9)

• Spatial variation in the fine-structure constant -- new results from VLT/UVES
• A Cosmology-Independent Calibration of Gamma-Ray Burst Luminosity Relations and the Hubble Diagram
• Power asymmetry in WMAP and Planck temperature sky maps as measured by a local variance estimator
• Dipole of the luminosity distance: a direct measure of H(z)
• Testing the Isotropy of the Universe with Type Ia Supernovae
• The peculiar velocity field: constraining the tilt of the Universe
• On the Possibility of Anisotropic Curvature in Cosmology
• Current Status Of Velocity Field Surveys: A Consistency Check
• Cosmography: Extracting the Hubble series from the supernova data

Cited by in corpus (17)

• Gamma-ray Burst Cosmology
• Anisotropy of the Universe via the Pantheon supernovae sample revisited
• High-redshift cosmography: Application and comparison with different methods
• Testing the isotropy of the Universe with type Ia supernovae in a model-independent way
• Calibrating Gamma-Ray Bursts by Using a Gaussian Process with Type Ia Supernovae
• Constraining the anisotropy of the Universe via Pantheon supernovae sample
• Bianchi Type I model of universe with customized scale factors
• The deceleration parameter in `tilted' universes: generalising the Friedmann background
• Testing cosmic anisotropy with Pade approximation and Pantheon+ sample
• Cosmography of the Local Universe by Multipole Analysis of the Expansion Rate Fluctuation Field
• Consistency of Pantheon+ supernovae with a large-scale isotropic universe
• Anisotropic universe with anisotropic dark energy
• Probing the Cosmological Principle with weak lensing shear
• The Two-Point Correlation Function of Gamma-ray Bursts
• Expanding covariant cosmography of the local Universe: incorporating the snap and axial symmetry
• New Constraints on Anisotropic Expansion from Supernovae Type Ia
• Measuring cosmic dipole with the GRB luminosity-time relation