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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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Multi-spectral analysis of a gamma-ray burst
Maleňáková, Alžběta ; Jelínek, Martin (advisor) ; Münz, Filip (referee)
Gamma-ray bursts are fascinating high energy phenomena, related with supernovas and black holes, which were discovered by accident in the second half of the 20. century. The goal of this thesis is to perform a multi-spectral analysis of the GRB 190919B after becoming familiar with the elementary knowledge about this phenomena. The images of an optical afterglow from robotic telescopes FRAM and BOOTES enabled us to construct the photometric light curve of the given burst. Together with the publicly available data from other spectral fields, the spectral energy distribution could be created. Afterwards, we fitted both obtained graphs with several functions with different choices of constraining parameters. Through analysis of the acquired values, we obtained several variants of the scenario of the observed event. By determining the value of initial Lorentz factors, we confirmed that all the options lie within the boundaries of typical values for the model of relativistic fireball. 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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Statistical analysis of the gamma-ray bursts satellite data
Bystřický, Pavel ; Mészáros, Attila (advisor) ; Brož, Miroslav (referee)
In this thesis the Gamma-Ray Bursts (GRBs) are studied, the brightest explosions in the universe. GRBs have been observed since year 1967, but there are several unsolved problems. In the first chapter there is an introduction to the issue of GRBs, and the history of observations are briefly described. The Fermi satellite, the latest satellite devoted to gamma-ray burst observations is described in chapter two. Characteristics of the Fermi instruments are also described. The observed data of GRBs are characterized in the third chapter. The distribution of GRB durations, distances, and spectral hardnesses are described. The characteristics of long and short GRBs (distance, isotropy of distribution, metalicity dependence, isotropic energy) are described. A chance of the appearance of a GRB in the Milky Way is discussed. New Fermi observations are described too. Fourth chapter is about models of GRBs. The fireball and canonball models are described. Fifth chapter is focused on the exposure function of CGRO-BATSE, Fermi-GBM, Swift. I have created the exposure function for GBM on Fermi satellite. It is quite difficult, and I have assumed some simplified hypotheses. Information of the satellite's position, position of detectors on the Fermi satellite, have been found on the Fermi web pages and in the article...
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