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Statistical Analysis of the Observable Data of Gamma-Ray Bursts
Řípa, Jakub ; Mészáros, Attila (advisor) ; Münz, Filip (referee) ; Ramirez-Ruiz, Enrico Jorge (referee)
Gamma-ray bursts are still not fully understood events. However, their exploration could pro- vide a useful tool for a better understanding of the early Universe because they belong to the most distant and violent objects that astronomers know. This thesis tries to bring more information about a so-called group of intermediate-duration bursts claimed by different authors employing dif- ferent data samples. Firstly, duration and spectral hardness properties of bursts from the Reuven Ramaty High-Energy Solar Spectroscopic Imager are statistically analysed. The obtained results bring a suspicion that these intermediate bursts gather into a separate group. Secondly, these bursts are investigated in more detail with respect to their spectral lags, peak count rates, red- shifts, supernova observations, and so forth. Thirdly, long-duration bursts with known redshifts and with derived pseudo-redshifts detected by The Burst and Transient Source Experiment, Swift and Fermi bursts with known redshifts, are used to study the cosmological effects on the observed flux and fluence distributions.
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Statistical Analysis of the Observable Data of Gamma-Ray Bursts
Řípa, Jakub ; Mészáros, Attila (advisor)
Gamma-ray bursts are still not fully understood events. However, their exploration could pro- vide a useful tool for a better understanding of the early Universe because they belong to the most distant and violent objects that astronomers know. This thesis tries to bring more information about a so-called group of intermediate-duration bursts claimed by different authors employing dif- ferent data samples. Firstly, duration and spectral hardness properties of bursts from the Reuven Ramaty High-Energy Solar Spectroscopic Imager are statistically analysed. The obtained results bring a suspicion that these intermediate bursts gather into a separate group. Secondly, these bursts are investigated in more detail with respect to their spectral lags, peak count rates, red- shifts, supernova observations, and so forth. Thirdly, long-duration bursts with known redshifts and with derived pseudo-redshifts detected by The Burst and Transient Source Experiment, Swift and Fermi bursts with known redshifts, are used to study the cosmological effects on the observed flux and fluence distributions.
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Solar Flares from Optical to X-ray Emission
Nejedlý, Jaroslav ; Kašparová, Jana (advisor) ; Řípa, Jakub (referee)
Solar flare is a phenomenon during which a large amount of energy is released in various forms. Part of this energy is released in form of different electromagnetic radiation. By analysing hard X-ray spectra of such emission it is possible to derive various parameters of a flare. Thanks to accurate images of solar atmosphere in comparatively high resolution, it is possible to analyse spatial structure of solar flares. By combining data from RHESSI, SDO, GOES, and ground-based observatories, it is feasible to gain an overview of various aspects of solar flares. Combination of multiple different observations of same event will allow us to compare obtained results. The result of this thesis is an analysis of spectra and spatial structures of two selected flares and derivation of their parameters. 1
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Statistické zpracování družicových dat gama záblesků družice Fermi
Pitňa, Alexander ; Mészáros, Attila (advisor) ; Řípa, Jakub (referee)
Gamma-ray bursts (GRBs) are one of the phenomena that still puzzle the astrophysi- cists. Due to their extreme luminosities, they are visible in cosmological distances. They could provide a tool for understanding the early Universe. This thesis focuses on the estimation of the total energy released by the GRBs, their luminosities and how these quantities depend on the redshift. For a sample of 28 long GRBs with known redshifts, a dependence of their total energies and luminosities on the redshift is found. The thesis further studied if this dependence is either an observational bias or a real astrophysical phenomenon. Firstly, proper use of k-correction revealed that it has lit- tle effect on the redshift dependence of these quantities. Secondly, a new approach has been proposed to investigate the redshift dependence of the luminosity function. Thirdly, selection effect has been found, when investigating the sample of bursts with known redshifts, implying a caution when combining data from different sources. All these efforts show that the observational bias can still explain the redshift dependence.
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Statistical Analysis of the Observable Data of Gamma-Ray Bursts
Řípa, Jakub ; Mészáros, Attila (advisor)
Gamma-ray bursts are still not fully understood events. However, their exploration could pro- vide a useful tool for a better understanding of the early Universe because they belong to the most distant and violent objects that astronomers know. This thesis tries to bring more information about a so-called group of intermediate-duration bursts claimed by different authors employing dif- ferent data samples. Firstly, duration and spectral hardness properties of bursts from the Reuven Ramaty High-Energy Solar Spectroscopic Imager are statistically analysed. The obtained results bring a suspicion that these intermediate bursts gather into a separate group. Secondly, these bursts are investigated in more detail with respect to their spectral lags, peak count rates, red- shifts, supernova observations, and so forth. Thirdly, long-duration bursts with known redshifts and with derived pseudo-redshifts detected by The Burst and Transient Source Experiment, Swift and Fermi bursts with known redshifts, are used to study the cosmological effects on the observed flux and fluence distributions.
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Statistical Analysis of the Observable Data of Gamma-Ray Bursts
Řípa, Jakub ; Mészáros, Attila (advisor) ; Münz, Filip (referee) ; Ramirez-Ruiz, Enrico Jorge (referee)
Gamma-ray bursts are still not fully understood events. However, their exploration could pro- vide a useful tool for a better understanding of the early Universe because they belong to the most distant and violent objects that astronomers know. This thesis tries to bring more information about a so-called group of intermediate-duration bursts claimed by different authors employing dif- ferent data samples. Firstly, duration and spectral hardness properties of bursts from the Reuven Ramaty High-Energy Solar Spectroscopic Imager are statistically analysed. The obtained results bring a suspicion that these intermediate bursts gather into a separate group. Secondly, these bursts are investigated in more detail with respect to their spectral lags, peak count rates, red- shifts, supernova observations, and so forth. Thirdly, long-duration bursts with known redshifts and with derived pseudo-redshifts detected by The Burst and Transient Source Experiment, Swift and Fermi bursts with known redshifts, are used to study the cosmological effects on the observed flux and fluence distributions.
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The study of gamma-ray bursts detected by satellite RHESSI
Řípa, Jakub ; Mészáros, Attila (advisor) ; Karas, Vladimír (referee)
The beginning of the theoretical section of this diploma thesis is pointed to a discovery of the gamma-ray bursts. Then it is pointed to a brief historical summary of the different instruments dedicated to the GRB's field. Because the main aim of this work is the basic analysis and the classifying of the observed gamma-ray bursts by RHESSI solar satellite (which has observed more than 220 GRBs yet), a technical description of this instrument is introduced. It is followed by a part about gamma-ray production mechanisms. In this work there are also mentioned some related gamma-ray sources e.g. SGRs. The theoretical résumé is concluded by the description of the GRB's afterglows and some preferred models of their origins. In the proper study there was done the morphological classifying of the GRB's temporal profiles. Next there was studied the duration distribution with orientation to determine number of the subclasses using lognormal fits and the 2 test. Distribution of the radial distances of the gamma-ray sources can be examined by the log N vs. log P. dependence. The results are properly discussed and compared with the results of the BATSE instrument (including the V/Vmax test). In the final stage of this work, there is argued the dependence between the hardness ratios and the durations.
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