@phdthesis{Bustamante2014,
  author    = {Bustamante, Mauricio},
  title     = {Ultra-high-energy neutrinos and cosmic rays from gamma-ray bursts: exploring and updating the connection},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-112480},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2014},
  abstract  = {It is natural to consider the possibility that the most energetic particles detected (> 10^18 eV), ultra-high-energy cosmic rays (UHECRs), are originated at the most luminous transient events observed (> 10^52 erg s^-1), gamma-ray bursts (GRBs). As a result of the interaction of highly-accelerated, magnetically-confined protons and ions with the photon field inside the burst, both neutrons and UHE neutrinos are expected to be created: the former escape the source and beta-decay into protons which propagate to Earth, where they are detected as UHECRs, while the latter, if detected, would constitute the smoking gun of hadronic acceleration in the sources. Recently, km-scale neutrino telescopes such as IceCube have finally reached the sensitivities required to probe the neutrino predictions of some of the existing GRB models. On that account, we present here a revised, self-consistent model of joint UHE proton and neutrino production at GRBs that includes a state-of-the-art, improved numerical calculation of the neutrino flux (NeuCosmA); that uses a generalised UHECR emission model where some of the protons in the sources are able to "leak out" of their magnetic confinement before having interacted; and that takes into account the energy losses of the protons during their propagation to Earth. We use our predictions to take a close look at the cosmic ray-neutrino connection and find that the current UHECR observations by giant air shower detectors, together with the upper bounds on the flux of neutrinos from GRBs, are already sufficient to put tension on several possibilities of particle emission and propagation, and to point us towards some requirements that should be fulfilled by GRBs if they are to be the sources of the UHECRs. We further refine our analysis by studying a dynamical burst model, where we find that the different particle species originate at distinct stages of the expanding GRB, each under particular conditions. Finally, we consider a possibility of new physics: the effect of neutrino decay in the flux of UHE neutrinos from GRBs. On the whole, our results demonstrate that self-consistent models of particle production are now integral to the advancement of the field, given that the full picture of the UHE Universe will only emerge as a result of looking at the multi-messenger sky, i.e., at gamma-rays, cosmic rays, and neutrinos simultaneously.},
  subject      = {Gamma-Burst},
  language  = {en}
}
@phdthesis{Baerwald2013,
  author    = {Baerwald, Philipp},
  title     = {Neutrinos from gamma-ray bursts, and the multi-messenger connection},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-85333},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2013},
  abstract  = {In this work, we take a look at the connection of gamma-ray bursts (GRBs) and ultra-high-energy cosmic rays (UHECR) as well as the possibilities how to verify this connection. The currently most promising approach is based on the detection of high-energy neutrinos, which are associated with the acceleration of cosmic rays. We detail how the prompt gamma-ray emission is connected to the prediction of a neutrino signal. We focus on the interactions of photons and protons in this regard. At the example of the current ANTARES GRB neutrino analysis, we show the differences between numerical predictions and older analytical methods. Moreover, we discuss the possibilities how cosmic ray particles can escape from GRBs, assuming that UHECR are entirely made up of protons. For this, we compare the commonly assumed neutron escape model with a new component of direct proton escape. Additionally, we will show that the different components, which contribute to the cosmic ray flux, strongly depend on the burst parameters, and test the applicability on some chosen GRBs. In a further step, we continue with the considerations regarding the connection of GRBs and UHECR by connecting the GRB source model with the cosmic ray observations using a simple cosmic ray propagation code. We test if it is possible to achieve the observed cosmic ray energy densities with our simple model and what the consequences are regarding the prompt GRB neutrino flux predictions as well as the cosmogenic neutrinos. Furthermore, we consider the question of neutrino lifetime and how it affects the prompt GRB neutrino flux predictions. In a final chapter, we show that it is possible to apply the basic source model with photohadronic interactions to other types of sources, using the example of the microquasar Cygnus X-3.},
  subject      = {Neutrino},
  language  = {en}
}
@phdthesis{Huemmer2013,
  author    = {H{\"u}mmer, Svenja},
  title     = {Neutrinos aus photohadronischen Wechselwirkungen in kosmischen Beschleunigern},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-77519},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2013},
  abstract  = {In dieser Arbeit untersuchen wir die Produktion von Neutrinos in astrophysikalischen Quellen. Bei der Beschreibung der Wechselwirkung betrachten wir resonante, direkte und Multipion-Produktion. Zus{\"a}tzlich ber{\"u}cksichtigen wir die Produktion von Neutronen und positiv geladenen Kaonen. Wir beachten explizit die Energieverluste der Sekund{\"a}rteilchen - Pionen, Myonen und Kaonen - auf Grund von Synchrotronstrahlung derselben und adiabatischer Expansion. In Bezug auf den Neutrinofluss ber{\"u}cksichtigen wir Flavor-Mischungen der Neutrinos auf dem Weg zum Beobachter. Zun{\"a}chst f{\"u}hren wir eine Analyse basierend auf einem generischen Quellmodell durch, in der wir den Einfluss von Magnetfeld und Gr{\"o}ße der Quelle auf die Neutrinospektren und das Verh{\"a}ltnis der verschiedenen Neutrino-Flavor untersuchen. Es stellt sich heraus, dass man im Rahmen dieses generischen Modells verschiedene Regionen im Parameterraum anhand des Flavor-Verh{\"a}ltnisses, das f{\"u}r hohe Magnetfelder von dem zumeist angenommenen Verh{\"a}ltnis (nu_e:nu_mu:nu_tau)=(1:2:0) abweicht, klassifizieren kann. In einer zweiten Analyse bestimmen wir die erwarteten Neutrinospektren von Gammablitzen im Rahmen des Feuerball-Modells aus beobachteten Photonspektren. Es zeigt sich, dass auf Grund grober Absch{\"a}tzungen in der Literatur, der Neutrinofluss zumeist um etwa eine Gr{\"o}ßenordnung {\"u}bersch{\"a}tzt wird. Deshalb berechnen wir den erwarteten Neutrinofluss der Gammablitze neu, die w{\"a}hrend der 40-Leinen-Konfiguration des IceCube-Detektors gemessen wurden, und folgern, dass entgegen der Behauptung der IceCube-Kollaboration, das Feuerball-Modell noch nicht ausgeschlossen ist. Des Weiteren quantifizieren wir systematische und astrophysikalische Unsicherheiten in dem vorhergesagten Neutrinofluss.},
  subject      = {Neutrino},
  language  = {de}
}