A survey of the theory of neutrino oscillations in dense matter and neutrino backgrounds is presented. We discuss collective neutrino systems using the gyroscopic pendulum analogy and describe the motion that results from self-induced parametric resonances. The effects of dense matter on the flavour oscillations of neutrinos are also detailed. This theory is applied to the case of continuous supernova neutrino spectra and explanations of the spectral swapping behaviour seen in numerical studies are summarized. The results of numerical simulations of supernova oscillations in turbulent supernova backgrounds are presented and discussed. We study the motion of two example supernova neutrino spectra and examine the differences in the dynamics and flavour evolution that results from adding turbulent fluctuations to the supernova matter background. We also investigate the effect that fluctuations in the neutrino density can have on the oscillation behaviour. We find that in general the final neutrino spectra emerging from the inner supernova regions are quite robust to fluctuations in the backgrounds in our model, while the intermediate dynamics can be very strongly altered. Some significant changes in the final spectra are also found to occur when the neutrino background density fluctuations are large. We give a detailed review of the resonant matter effects that determine the survival probabilities of atmospheric muon neutrinos. The differences between various Earth density models are described, and these models are then used to predict the flux of muon-type neutrino events in the Deep Core extension to the IceCube detector. We use recent results from the detector collaboration and build on previous work which considered the sensitivity of the detector to the mass hierarchy, and show that uncertainties in the Earth's density can have a significant influence on the event rates.

It is astonishing both how little and how much we know about neutrinos. On one hand, the neutrino is the second most abundant particle in our Universe. Neutrinos may be created in the Sun, core collapse supernovae, cosmic rays, geological background radiation, supernova remnants and in the Big Bang. On the other hand, they have unimaginably small masses and are unwilling to react with their surroundings. Because of their abundance and their inclination to show us physics beyond the standard model of particle physics, neutrinos are hoped to carry yet unknown information of the Universe. However, it will take some effort and time to persuade the neutrinos to tell us what they know. Among the things we do not yet know of the neutrinos, is the -phase in the neutrino mixing matrix. If is in fact non-zero, neutrino flavour oscillations violate CP-symmetry. Also, if neutrino masses are introduced in the standard model through the See-Saw mechanism and if leptogenesis is a valid theory, CP-violation in neutrino oscillations could help explain why our Universe has no antimatter even though equal amounts of matter and antimatter should have been created at the Big Bang. In this thesis, we investigate the flavour evolution of supernova neutrinos. We present the full Hamiltonian in the flavour basis for our system and identify how the different contributions affect the evolution and in which environment. We also present a theoretical motivation from [1, 2] as to how a non-zero -phase affects the flavour evolution and the final energy spectra. The analytical conclusion is that it has no impact under the assumptions made in our analysis. Thus, the -phase may not be measurable from supernova neutrinos.

One of the most significant current discussions in Astrophysics relates to the origin of high-energy cosmic rays. According to our current knowledge, the abundance distribution of the elements in cosmic rays at their point of origin indicates, within plausible error limits, that they were initially formed by nuclear processes in the interiors of stars. It is also believed that their energy distribution up to 1018 eV has Galactic origins. But even though the knowledge about potential sources of cosmic rays is quite poor above „ 1015 eV, that is the “knee” of the cosmic-ray spectrum, up to the knee there seems to be a wide consensus that supernova remnants are the most likely candidates. Evidence of this comes from observations of non-thermal X-ray radiation, requiring synchrotron electrons with energies up to 1014 eV, exactly in the remnant of supernovae. To date, however, there is not conclusive evidence that they produce nuclei, the dominant component of cosmic rays, in addition to electrons. In light of this dearth of evidence, γ-ray observations from supernova remnants can offer the most promising direct way to confirm whether or not these astrophysical objects are indeed the main source of cosmic-ray nuclei below the knee. Recent observations with space- and ground-based observatories have established shell-type supernova remnants as GeV-to- TeV γ-ray sources. The interpretation of these observations is however complicated by the different radiation processes, leptonic and hadronic, that can produce similar fluxes in this energy band rendering ambiguous the nature of the emission itself. The aim of this work is to develop a deeper understanding of these radiation processes from a particular shell-type supernova remnant, namely RX J1713.7–3946, using observations of the LAT instrument onboard the Fermi Gamma-Ray Space Telescope. Furthermore, to obtain accurate spectra and morphology maps of the emission associated with this supernova remnant, an improved model of the diffuse Galactic γ-ray emission background is developed. The analyses of RX J1713.7–3946 carried out with this improved background show that the hard Fermi-LAT spectrum cannot be ascribed to the hadronic emission, leading thus to the conclusion that the leptonic scenario is instead the most natural picture for the high-energy γ-ray emission of RX J1713.7–3946. The leptonic scenario however does not rule out the possibility that cosmic-ray nuclei are accelerated in this supernova remnant, but it suggests that the ambient density may not be high enough to produce a significant hadronic γ-ray emission. Further investigations involving other supernova remnants using the improved back- ground developed in this work could allow compelling population studies, and hence prove or disprove the origin of Galactic cosmic-ray nuclei in these astrophysical objects. A break- through regarding the identification of the radiation mechanisms could be lastly achieved with a new generation of instruments such as CTA. / Eine der gegenwärtigen bedeutendsten geführten Diskussionen in der Astrophysik bezieht sich auf den Ursprung der hochenergetischen Kosmischen Strahlung. Nach unserem heutigen Verständnis weist die am Ort des Ursprungs elementare Zusam- mensetzung der Kosmischen Strahlung darauf hin, dass diese zu Beginn mittels nuklearer Prozesse im Inneren von Sternen gebildet wurde. Weiterhin wird ange- nommen, dass die Kosmische Strahlung bis 1018 eV galaktischen Ursprungs ist. Auch wenn das Verständnis über die potentiellen Quellen der Kosmischen Strahlung ober- halb von 1015 eV, dem sogenannten „Knie“ des Spektrums der Kosmischen Strah- lung, lückenhaft ist, so liegt doch der Konsens vor, dass Supernovaüberreste (SNR) die wahrscheinlichsten Quellen für Energien bis 1015 eV sind. Unterstützt wird die- ser Sachverhalt durch Beobachtungen von nichtthermischer Röntgenstrahlung von SNR, deren Emission Elektronen mit Energien bis zu 1014 eV erfordern. Jedoch gibt es bis heute keinen überzeugenden Beweis, dass SNR zusätzlich zu den Elektronen auch Atomkerne, die den dominierenden Anteil in der Kosmischen Strahlung bilden, beschleunigen. Trotz fehlender überzeugender Beweise ermöglichen nun Beobachtungen von SNR im γ-Strahlungsbereich einen vielversprechenden Weg zur Aufklärung der Fra- ge, ob diese astrophysikalischen Objekte in der Tat die Hauptquelle der Kosmischen Strahlung unterhalb des Knies sind. Kürzlich durchgeführte Beobachtungen im Welt- raum und auf der Erdoberfläche haben zu der Erkenntnis geführt, dass schalenartige SNR γ-Strahlung im GeV- und TeV-Bereich emittieren. Die Interpretation dieser Beobachtungen ist jedoch schwierig, da sowohl Atomkerne als auch Elektronen im betrachteten Energiebereich zu ähnlichen γ-Emissionen führen. Dadurch wird die eindeutige Identifizierung der Emission als das Resultat hadronischer oder leptoni- scher Emissionsprozesse erschwert. Das Ziel dieser Arbeit ist es, am Beispiel des schalenartigen SNR RX J1713.7- 3946 ein tieferes Verständnis über die Strahlungsprozesse zu erhalten, indem vom γ-Weltraumteleskop Fermi durchgeführte Beobachtungen analysiert werden. Um ge- naue Spektren und die Ausdehnung der Region der Emission zu erhalten, wird ein verbessertes Modell für die diffuse galaktische γ-Hintergrundstrahlung entwickelt. Die mit diesem verbesserten Hintergrund durchgeführte Analyse von RX J1713.7- 3946 zeigt, dass das vom Fermi-Satelliten beobachtete Spektrum nicht dem hadro- nischen Szenario zugeschrieben werden kann, sodass das leptonische Szenario für die γ-Emissionen von diesem SNR verantwortlich ist. Das leptonische Szenario schließt jedoch nicht die Möglichkeit aus, dass auch Atomkerne in diesem SNR beschleu- nigt werden. Aber es deutet darauf hin, dass die umgebende Teilchendichte nicht ausreichend hoch genug ist, um zu einer signifikanten hadronischen γ-Emission zu führen. Weitere Untersuchungen, die andere SNR in Kombination mit dem hier ent- wickelten verbesserten Modell der Hintergrundstrahlung beinhalten, können Popu- lationsstudien erlauben. Dies könnte klären, ob die SNR tatsächlich die Quellen der galaktischen Kosmischen Strahlung sind. Ein Durchbruch bezüglich der Identi- fikation des Strahlungsmechanismus könnte auch durch eine neue Generation von Beobachtungsinstrumenten, wie das Cherenkov Telescope Array, erreicht werden.

Studying how SN Ia rates (SNR) correlate with host galaxy properties is an important step in understanding the exact nature of SN Ia. Taking a sample of SNe and galaxies from the SDSS, we obtain the optimum parameter values for the A+B model for SNR, which states that SNR scale linearly with mass and star formation rate of the host, and compare them with previous work. We then proceed to show that the A+B model deviates very significantly from the SNR behaviour in our sample, demonstrate that no reasonable values for A and B could possibly match the observations, and investigate the possibility of a third-parameter correction to the generic A+B model. We find that several hypothesised models seem to match the distribution of SNRs in our sample; however, discriminating between them is a difficult task. We interpret the above to be an indicator that a new parameter may need to be taken into account when modelling SNR, and we present metallicity as a possible candidate for the new parameter. Also, by investigating decomposed bulge + disk components of the host galaxies, we find that the spatial positions of SNe Ia are correlated with bulge luminosity, but not with galaxy total luminosity or disk luminosity. It is also shown that SNe do not preferentially occur in bulge-dominated galaxies. Our interpretation of these results is that SNe arise from a population having a spatial distribution which correlates very well with bulge luminosity, but does not usually contribute to bulge luminosity. / Graduate

This thesis considers the various morphologies of radio supernova remnants (SNRs), and attempts to determine whether their appearance results from the properties of the progenitor star and its supernova explosion, or from the structure of the interstellar medium (ISM) and ambient magnetic field into which a SNR consequently expands. High-resolution observations of Supernova 1987A show a young remnant whose appearance and evolution are completely dominated by the structure of its progenitor wind. A statistical study of the Galactic population of bilateral SNRs demonstrates that the symmetry axes of these remnants run parallel to the Galactic Plane. This result can be explained by the interaction of main sequence stellar wind-bubbles with the ambient magnetic field; expansion of SNRs into the resulting elongated cavities results in a bilateral appearance with the observed alignment. Radio observations of SNR G296.8-00.3 show a double-ringed morphology which is best explained by expansion either into an anisotropic main-sequence progenitor wind or into multiple cavities in the ISM. Data on SNRs G309.2-00.6 and G320.4-01.2 (MSH 15-52) make a strong case that the appearance of both remnants is significantly affected by collimated outflows from a central source; for G309.2-00.6 the source itself is not detected, but for G320.4-01.2 there is now compelling evidence that the remnant is associated with and is interacting with the young pulsar PSR B1509-58. I conclude that, while the youngest SNRs are shaped by their progenitor's circumstellar material, the appearance of most SNRs reflects the properties of the local ISM and magnetic field. Remnants which interact with an associated pulsar or binary system appear to be rare, and are easily distinguished by their unusual and distorted morphologies.

Thesis (Doctoral)--Technische Universität München, 1993. / "August 1993." Includes bibliographical references (p. 108-111).

Orientadores: Armando Turtelli Junior, Walter Fulgione / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica "Gleb Wataghin" / Made available in DSpace on 2018-07-27T10:14:30Z (GMT). No. of bitstreams: 1 Kemp_Ernesto_D.pdf: 10809239 bytes, checksum: 5d7a350deea9c8243bf06529cab72464 (MD5) Previous issue date: 2000 / Resumo: São descritos os principais aspectos da fenomenologia de colapsos gravitacionais estelares e ocorrência de supernovas. Também são apresentados os principais modelos que descrevem a emissão de neutrinos que acompanha esse tipo de evento astrofísico. Segue um panorama atual da astronomia neutrínica, com uma descrição detalhada do experimento LVD, cujo objetivo principal é a detecção de neutrinos de colapsos estelares. Ainda com relação ao LVD, discutem-se as medidas realizadas com um composto alternativo de cintilador, aditivado com gadolínio, que mostraram a melhoria alcançada no desempenho do módulo de detecção de neutrinos. É introduzido o formalismo de composição do sinal experimental de um burst de neutrinos de colapso, e são discutidas as características do sinal esperado no LVD. Os modelos de emissão neutrínica acima citados são usados como referência no cálculo do número de eventos esperados no experimento para um colapso localizado no centro da Galáxia. Considerando a proporção entre o número de eventos em diferentes canais de detecção do LVD e a energia média do espectro esperado de ¯ve, é possível estabelecer critérios para caracterizar os espectros de emissão e determinar seus parâmetros. A resolução alcançada com esse método foi obtida por simulações numéricas do sinal do LVD, considerando-se incertezas estatísticas e instrumentais. Finalizando, discutem-se efeitos da oscilação de neutrinos sobre o sinal esperado no LVD. Utilizando o formalismo de pacotes de onda, pode-se mostrar que a propagação no vácuo em distâncias astronômicas é incoerente, desacoplando os auto-estados de massa e cessando as oscilações. Entretanto, as conversões de sabor são ainda possíveis, e o fluxo de neutrinos das diferentes espécies deve atingir a Terra com seus espectros repopulados. Uma conseqüência desse fenômeno é uma possível ambigüidade na interpretação dos dados do LVD / Abstract: Not informed. / Doutorado / Física / Doutor em Ciências

Orientadores: Armando Turtelli Junior, Walter Fulgione / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica "Gleb Wataghin" / Made available in DSpace on 2017-09-22T15:37:17Z (GMT). No. of bitstreams: 1 Kemp_Ernesto_D.pdf: 2628544 bytes, checksum: 6f538296a3f66617097b7f9b6c072be2 (MD5) Previous issue date: 2000 / Resumo: São descritos os principais aspectos da fenomenologia de colapsos gravitacionais estelares e ocorrência de supernovas. Também são apresentados os principais modelos que descrevem a emissão de neutrinos que acompanha esse tipo de evento astrofísico. Segue um panorama atual da astronomia neutrínica, com uma descrição detalhada do experimento LVD, cujo objetivo principal é a detecção de neutrinos de colapsos estelares. Ainda com relação ao LVD, discutem-se as medidas realizadas com um composto alternativo de cintilador, aditivado com gadolínio, que mostraram a melhoria alcançada no desempenho do módulo de detecção de neutrinos. É introduzido o formalismo de composição do sinal experimental de um burst de neutrinos de colapso, e são discutidas as características do sinal esperado no LVD. Os modelos de emissão neutrínica acima citados são usados como referência no cálculo do número de eventos esperados no experimento para um colapso localizado no centro da Galáxia. Considerando a proporção entre o número de eventos em diferentes canais de detecção do LVD e a energia média do espectro esperado de ¯ve, é possível estabelecer critérios para caracterizar os espectros de emissão e determinar seus parâmetros. A resolução alcançada com esse método foi obtida por simulações numéricas do sinal do LVD, considerando-se incertezas estatísticas e instrumentais. Finalizando, discutem-se efeitos da oscilação de neutrinos sobre o sinal esperado no LVD. Utilizando o formalismo de pacotes de onda, pode-se mostrar que a propagação no vácuo em distâncias astronômicas é incoerente, desacoplando os auto-estados de massa e cessando as oscilações. Entretanto, as conversões de sabor são ainda possíveis, e o fluxo de neutrinos das diferentes espécies deve atingir a Terra com seus espectros repopulados. Uma conseqüência desse fenômeno é uma possível ambigüidade na interpretação dos dados do LVD / Abstract: Not informed. / Doutorado / Física / Doutor em Ciências

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Since the observation of the supernova event SN 1987A, observational research on supernova and supernova remnants, including the ones on the optical spectrum, has been much explored. However, most of these studies have been limited to present integrated or punctual data from extragalactic or galactic supernova remnants. The present work has the objective of presenting some physical and kinematic properties from the galactical supernova remnant RCW 103, not limiting itself to punctual measures. Long slit two-dimensional spectra were obtained through spectrophotometric measures with high signal-noise in the range of 6000 to 7000 A, by using the Cassegrain spectrograph attached to 1.6 m telescope of the Observatório Pico dos Dias. With the slit on the East-West direction and with exposure time of 1200~3, the galactical nebula RCW 103 was swept at 14 different declinations, a11 the times with a distance of 5". As a first step, one-dimensional spectra at 4.6" one from each other in right ascension were extracted, allowing the construction of two-dimensional maps of the Ha flux and of the electron density. Maps with a special resolution of 4.6" x 5" for these two physical properties were obtained. As a second step, from the same two-dimensional spectra, spectra with apertures of 2.3" were extracted, from which measures of the center of the Ha line and its width at half maximum were estimated. Based on these two measures, the maps of radial velocity and of the width at half maximum itself were constructed, both of them with resolution around of 2.3" x 5". As a sensor of electron density, the [SII] (X6717/X6731) lines ratio was used, generating an irregular distribution of electron density around 1433 15 ~ m - ~ . At South-East from RCW 103, a region with electron density sistematically higher was observed, maybe a result from the interaction between the shock wave with a molecular cloud. In the radial velocity map, velocity measures from -200 to +I00 kms-', with a mean radial velocity of -22 kms-' in relation to the local standard of rest, were found. Due to the large dispersion velocity in the internal part of the region observed, maps were constructed to show the nebular regions in which the emission lines present two components. The mean velocity dispersion observed was aproximately 76 kms-'. Finally, taking these measures as a referente, it was possible to estimate the kinematic distance of the region observed, its respective mass, as well as the turbulence energy. The distance found corresponds aproximately to 1.75 f 0.08 kpc and the mass, around 3.2 Ma, with the energy associated to the internal movement at about 2.3 x 104' ergs. It is estimated that the mass of the nebula as a whole should be at least three or four times higher than the value presented. / Desde a observação do evento de supernova SN 1987A, o estudo observacional de supernovas e de remanescentes de supernova, inclusive no ótico, tem recebido atenção especial. No entanto, estudos observacionais no ótico têm se limitado, em sua grande maioria, a apresentar dados integrados ou de pontos específicos de remanescentes de supernova extragaiácticos e galácticos. Tendo isso em vista, no presente trabalho, realiza-se um estudo observacional de algumas propriedades físicas se cinemáticas do remanescente de supernova galáctico RCW 103, não limitando-se;a medidas pontuais. Espectros bidimensionais de fenda longa foram obtidos via medidas espectrofotométricas de alta razão sinal-ruído na faixa de 6000 a 7000 k, )para o que se utilizou o espectrógrafo Cassegrain acoplado ao telescópio de 1,6 m do Observatório Pico dos Dias (OPD), Brasópolis, MG. Com a fenda orientada *ao longo da direção Leste-oeste e em exposições de 1200s, varreu-se a nebulosa galáctica RCW 103 em 14 diferentes declinações, sempre com uma separação de 5". Em uma primeira etapa, foram extraídos espectros unidimensionais a cada 4,6" em ascensão reta, a partir dos quais foram confeccionados mapas bidimensionais do fluxo da linha Ha e da densidade eletrônica. Foram obtidos mapas com resolução espacial de aproximadamente 4,6" x 5" para essas duas propriedades físicas. Em uma segunda etapa, dos mesmos espectros bidimensionais, foram extraídos especkros com abertura de aproximadamente 2,3", a partir dos quais se mediram o centro da l i a Hol e a sua largura a meia altura. Dessas duas medidas, foram confeccionados os mapas de velocidade radial e da própria largura a meia altura, ambos com yesolução de cerca de 2,3" x 5". Como sensor de densidade eletrônica, utilizou-se ia razão de linhas [SII] (X6716/X6731), resultando em uma distribuição irregular de densídade eletrônica ao redor de 1433 * 15 cmT3. No lado Sudeste de RCW 103, encontrou-se uma região com densidade eletrônica sistematicamente maior, o que pode ser resultado da interação da frente de choque com uma nuvem molecular. Do mapa de velocidade radial, encontraram-se velocidades desde -200 a +I00 krns-', com uma velocidade radial média de -22 kms-' com relação ao padrão local de íepouso. Devido à grande dispersão de velocidades no interior da região observada, encontraram-se regiões nebulares onde as linhas de emissão apresentam duas componentes, para o que se confeccionaram mapas apresentando esses pontos. A média da dispersão de velocidades encontrada foi de aproximadamente 76 kms-l. Por fim, a partir dessas medidas, foi possível fazer algumas estimativas da distância cinemática da região observada, da massa correspondente, bem como da energia de turbulência. Encontrou-se a distância de aproximadamente 1,75 0,08 kpc e a massa de cerca de 3,2 M,, com energia associada ao movimento interno de aproximadamente 2,3 x 10" ergs. A massa da nebulosa como um todo pode ainda ser pelo menos três ou quatro vezes maior que o valor apresentado

The IceCube Neutrino Observatory consists of a lattice of 5160 photomultiplier tubes (PMTs)<p>which monitor one cubic kilometer of deep Antarctic ice at the geographic South Pole.<p>IceCube was primarily designed to detect neutrinos of energies greater than O(100 GeV).<p>Due to subfreezing ice temperatures, the photomultipliers' dark noise rates are particularly<p>low which enables IceCube to search for neutrinos from galactic supernovae by detecting<p>bursts of MeV neutrinos emitted during the core collapse and for several seconds following.<p>For that purpose, a dedicated online supernova DAQ system records the total number of hits<p>in the detector, without any further information from the PMTs, and generates supernova<p>candidate triggers in case of a significant detector rate enhancement. A new feature to the<p>standard DAQ, called HitSpooling, was implemented in IceCube during this thesis. The<p>HitSpooling system is implemented in the standard DAQ system and buffers the complete<p>raw data stream of the photomultipliers for several hours or days. By reading out time periods<p>of HitSpool data around supernova candidate triggers, generated by the online supernova<p>DAQ system, we overcome the limitations of the latter and have access to the entire information<p>of the detector in case of a supernova. Furthermore, HitSpool data is a powerful<p>source for studying and understanding the noise behavior of the detector as well as background<p>processes coming from atmospheric muons. The idea of HitSpooling was developed in the<p>scope of this thesis and is the basis of the work at hand. The developed interface between the<p>standard DAQ and the supernova DAQ system is presented. The correlated dark noise component<p>in optical modules of IceCube is quantified for the first time and possible explanations<p>are discussed. The possibility of identifying triggering and subthreshold atmospheric muons<p>in HitSpool data and subtracting them from a possible supernova signal is analyzed. Furthermore,<p>the conversion from HitSpool data to supernova DAQ type data was developed<p>which allows for a comparison of both data types with respect to lightcurves and significances<p>of selected supernova candidate triggers. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished