Comparison between hemisphere comparison method and dipole-fitting method in tracing the anisotropic expansion of the Universe use the Union2 data set. Issue 3 (29th November 2014)

• Record Type: Journal Article
• Authors: Chang, Zhe; Lin, Hai-Nan
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 446:Issue 3(2015)
• Page Start: 2952
• Page End: 2958
• Publication Date: 2014-11-29
• Subjects: supernovae: general -- large-scale structure of Universe; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stu2349
• Languages: English
• ISSNs: 0035-8711

Abstract

Abstract: Type Ia supernovae (SNe Ia) are often used as the standard candles to probe the anisotropic expansion of the Universe. In this paper, we make a comprehensive comparison between the hemisphere comparison (HC) method and dipole-fitting (DF) method in searching for the cosmological preferred direction using the Union2 data set, a compilation of 557 well-calibrated SNe Ia. We find that the directions of the faintest SNe Ia derived from these two methods are approximately opposite. Monte Carlo simulations show that the results of the HC method strongly depend on the distribution of the data points in the sky. The coincidence that the HC method and DF method give two completely opposite directions may be due to the extremely non-uniform distribution of the Union2 data set.