Weak gravitational lensing effects on cosmological parameters and dark energy from gamma-ray bursts

Abstract

Gamma-ray bursts (GRBs) are attractive objects for constraining the nature of dark energy in a way complementary to other cosmological probes, especially at high redshifts. However, the apparent magnitude of distant GRBs can be distorted by the gravitational lensing from the density fluctuations along the line of sight. We investigate the gravitational lensing effect on the cosmological parameters and dark energy equation of state from GRBs. We first calibrated the GRB luminosity relations without assuming any cosmological models. The luminosity distances of low-redshift GRBs were calibrated with the cosmography method using a latest type Ia supernova (SNe Ia) sample. We find that the gravitational lensing has non-negligible effects on the determination of cosmological parameters and dark energy. The gravitational lensing shifts the best-fit constraints on cosmological parameters and dark energy. Because high-redshift GRBs are more likely to be reduced, the most probable value of the observed matter density ${\Omega }_M$ is slightly lower than its actual value. In the $\Lambda$CDM model, we find that the matter density parameter ${\Omega }_M$ will shift from 0.30 to 0.26 after including the gravitational lensing effect. The gravitational lensing also affects the dark energy equation of state by shifting it to a more negative value. We constrain the dark energy equation of state out to redshift $z\sim 8$ using GRBs for the first time, and find that the equation of state deviates from $\Lambda$CDM at the $1\sigma$ confidence level, but agrees with $w=-1$ at the $2\sigma$ confidence level.

8 pages, 9 figures, 1 table, accepted for publication in Astronomy and Astrophysics

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• Standardized long gamma-ray bursts as a cosmic distance indicator
• Probing the anisotropic expansion from supernovae and GRBs in a model-independent way
• Measuring cosmological parameters with a luminosity-time correlation of gamma-ray bursts
• Searching for a preferred direction with Union2.1 data
• Calibrating Gamma-Ray Bursts by Using a Gaussian Process with Type Ia Supernovae
• Astronomical Distance Determination in the Space Age. Secondary distance indicators
• Testing Dark Energy Models with Gamma-Ray Bursts Calibrated from the Observational $H(z)$ Data through a Gaussian Process
• Constraints on dark energy from the Lyα forest baryon acoustic oscillations measurement of the redshift 2.3 Hubble parameter
• High Redshift Long Gamma-Ray Bursts Hubble Diagram as a Test of Basic Cosmological Relations
• Calibration of gamma-ray bursts luminosity correlations using gravitational waves as standard sirens
• Constraints on the cosmological parameters with three-parameter correlation of Gamma-ray bursts
• Recovering $\Lambda$CDM Model From a Cosmographic Study
• Reconciling the cosmic age problem in the R_h=ct Universe
• Similar radiation mechanism in gamma-ray bursts and blazars: evidence from two luminosity correlations
• GRBs and fundamental physics
• Cosmography with the Sunyaev-Zeldovich effect and X-ray data
• High Redshift Investigation On The Dark Energy Equation of State
• Standardizing the Gamma-ray burst as a standard candle and applying to the cosmological probes: constraints on the two-component dark energy model
• Swift/UVOT: 18 Years of Long GRB Discoveries and Advances