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您的检索式：作者名="Meghendra Singh"
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| 1 | Cosmology using long gamma-ray bursts: statistical analysis of errors in calibrated data显示文摘We investigate direction dependence and non-Gaussian features in high-z cosmological data using ?_(χ~2) and ?_χ statistics and the Kolmogorov-Smirnov test. These techniques are applied on a set of calibrated long gamma-ray bursts(GRBs) and its combination with recent Type Ia supernovae data(Union2). Our statistical analysis shows a weak but consistent direction dependence in both the data sets.The analysis also indicates a non-Gaussian nature of errors in both data sets. | Meghendra Singh Shashikant Gupta Amit Sharma Satendra Sharma | 2019 | Research in Astronomy and Astrophysics2019，19，2： | 0 |
| 2 | On the non-Gaussian errors in high-z supernovae type Ia data显示文摘The nature of random errors in any data set is Gaussian, which is a well established fact according to the Central Limit Theorem. Supernovae type Ia data have played a crucial role in major discoveries in cosmology. Unlike in laboratory experiments, astronomical measurements cannot be performed in controlled situations. Thus, errors in astronomical data can be more severe in terms of systematics and non-Gaussianity compared to those of laboratory experiments. In this paper, we use the Kolmogorov-Smirnov statistic to test non-Gaussianity in high-z supernovae data. We apply this statistic to four data sets, i.e., Gold data(2004),Gold data(2007), the Union2 catalog and the Union2.1 data set for our analysis. Our results show that in all four data sets the errors are consistent with a Gaussian distribution. | Meghendra Singh Ashwini Pandey Amit Sharma Shashikant Gupta Satendra Sharma | 2016 | Research in Astronomy and Astrophysics2016，16，11： | 0 |
| 3 | Investigating the Evolution of Amati Parameters with Redshift显示文摘Gamma-ray bursts(GRBs) are among the brightest objects in the Universe and, hence, can be observed up to a very high redshift. Properly calibrated empirical correlations between intensity and spectral correlations of GRBs can be used to estimate the cosmological parameters. However, the possibility of the evolution of GRBs with redshift is a long-standing puzzle. In this work, we used 162 long-duration GRBs to determine whether GRBs below and above a certain redshift have different properties. The GRBs are split into two groups, and we fit the Amati relation for each group separately. Our findings demonstrate that estimations of the Amati parameters for the two groups are substantially dissimilar. We perform simulations to investigate whether the selection effects could cause the difference. Our analysis shows that the differences may be either intrinsic or due to systematic errors in the data, and the selection effects are not their true origin. However, in-depth analysis with a new data set comprised of 119 long GRBs shows that intrinsic scatter may partly be responsible for such effects. | Meghendra Singh Darshan Singh Kanhaiya Lal Pandey Dinkar Verma Shashikant Gupta | 2024 | Research in Astronomy and Astrophysics2024，24，1： | 0 |
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