| 1. |
- Bagoly, Zsolt, et al.
(författare)
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Principal Component Analysis of Gamma-Ray Bursts' Spectra
- 2005
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Ingår i: Nuovo Cimento C. ; 28:3, s. 295-298
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Tidskriftsartikel (refereegranskat)abstract
- The origin of dark bursts--i.e. that have no observed afterglows in X-ray, optical/NIR and radio ranges--is unclear yet. Different possibilities--instrumental biases, very high redshifts, extinction in the host galaxies--are discussed and shown to be important. On the other hand, the dark bursts should not form a new subgroup of long gamma-ray bursts themselves.
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| 2. |
- Bagoly, Z., et al.
(författare)
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The Swift satellite and redshifts of long gamma-ray bursts - (Research Note)
- 2006
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 453:3, s. 797-800
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Tidskriftsartikel (refereegranskat)abstract
- Until 6 October 2005 sixteen redshifts had been measured of long gamma-ray bursts discovered by the Swift satellite. Further 45 redshifts have been measured of the long gamma- ray bursts discovered by other satellites. Here we perform five statistical tests comparing the redshift distributions of these two samples assuming as the null hypothesis an identical distribution for the two samples. Three tests (Student's t-test, Mann-Whitney test, Kolmogorov-Smirnov test) reject the null hypothesis at significance levels between 97.19 and 98.55%. Two different comparisons of the medians show extreme (99.78 - 99.99994)% significance levels of rejection. This means that the redshifts of the Swift sample and the redshifts of the non-Swift sample are distributed differently - in the Swift sample the redshifts are on average larger. This statistical result suggests that the long GRBs should on average be at the higher redshifts of the Swift sample.
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| 3. |
- Horvath, I., et al.
(författare)
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A new definition of the intermediate group of gamma-ray bursts
- 2006
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 447:1, s. 23-30
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Tidskriftsartikel (refereegranskat)abstract
- Gamma-ray bursts can be divided into three groups (short, intermediate, long) with respect to their durations. This classification is somewhat imprecise, since the subgroup of intermediate duration has an admixture of both short and long bursts. In this paper a physically more reasonable definition of the intermediate group is presented, using also the hardnesses of the bursts. It is shown again that the existence of the three groups is real, no further groups are needed. The intermediate group is the softest one. From this new definition it follows that 11% of all bursts belong to this group. An anticorrelation between the hardness and the duration is found for this subclass in contrast to the short and long groups. Despite this difference it is not clear yet whether this group represents a physically different phenomenon.
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| 4. |
- Meszaros, A., et al.
(författare)
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On the origin of the dark gamma-ray bursts
- 2005
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Ingår i: Nuovo cimento della societa italiana de fisica. C, Geophysics and space physics. - 1124-1896 .- 1826-9885. ; 28:3, s. 311-314
-
Tidskriftsartikel (refereegranskat)abstract
- The origin of dark bursts-i.e. that have no observed afterglows in X-ray, optical/NIR and radio ranges-is unclear yet. Different possibilities-instrumental biases, very high redshifts, extinction in the host galaxies-are discussed and shown to be important. On the other hand, the dark bursts should not form a new subgroup of long gamma-ray bursts themselves.
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| 5. |
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