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Extreme Particle Acceleration in Microquasar Jets and Pulsar Wind Nebulae with the MAGIC Telescopes

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ADVERTIMENT. Lʼaccés als continguts dʼaquesta tesi queda condicionat a lʼacceptació de les condicions dʼús establertes per la següent llicència Creative Commons: http://cat.creativecommons.org/?page_id=184 ADVERTENCIA. El acceso a los contenidos de esta tesis queda condicionado a la aceptación de las condiciones de uso establecidas por la siguiente licencia Creative Commons: http://es.creativecommons.org/blog/licencias/ WARNING. The access to the contents of this doctoral thesis it is limited to the acceptance of the use conditions set by the following Creative Commons license: https://creativecommons.org/licenses/?lang=en Extreme particle acceleration in microquasar jets and pulsar wind nebulae with the MAGIC telescopes Alba Fernandez´ Barral Departament de F´ısica Universitat Autonoma` de Barcelona A thesis submitted for the degree of PhilosophiæDoctor (PhD) October 2017 i Director: Dr. Oscar Blanch Bigas Tutor: Dr. Enrique Fernandez´ Sanchez´ IFAE IFAE & UAB Edifici Cn, UAB Edifici Cn, UAB 08193 Bellaterra (Barcelona), Spain 08193 Bellaterra (Barcelona), Spain [email protected] [email protected] Day of defense: 6 October 2017 ii iii Alla` ets l’essencia` de tot. Pels cr´ıtics, els paradigmes i els canons` pels que es regien estan obsolets de cop. Que amb l’aura que tu desprens s’imposa, de forma urgent, fer una revisio´ dels classics.` Que ets jove eternament. Els amics de les arts Museu d’Hist`oriaNatural A mis padres, a BRAIS. Os pertenece cada palabra aqu´ıescrita. iv I herewith declare that I have produced this thesis without the prohibited assistance of third parties and without making use of aids other than those specified; notions taken over directly or indirectly from other sources have been identified as such. This paper has not previously been presented in identical or similar form to any other Spanish or foreign examination board. The thesis work was conducted from September 2013 to October 2017 under the supervision of Oscar Blanch Bigas at Barcelona. Barcelona, 6 October 2017. v vi Abstract Throughout our entire history, we humans have strived to unravel the mysteries with which the deep Universe challenges us. In our humble beginnings, this task was performed with our naked eyes, by gazing at the stars and planets and wondering how far away they were and how they moved in the night sky. For many centuries, only the visible Universe was reachable for us, but extraordinary achievements were accomplished despite the limited tools: we discovered, for example, that our planet was not the center of the Universe, owing to Nicolaus Copernicus’ observations and his heliocentric model. From Copernicus’ epoch up to now, the development of new technologies and the advancement of our own understanding of the Cosmos, allowed us to disentangle many riddles. Fortunately, this natural curiosity that leads us to im- prove never ends, and we face new questions that challenge our capacity as scientists. In the present thesis, I focus on a small fraction of this science: the gamma-ray as- tronomy. Within this field, I study particle acceleration and gamma-ray production mechanisms inside the relativistic jets displayed by the so-called microquasars and the shocks produced in Pulsar Wind Nebulae (PWNe). In Part I of the thesis I present an introduction to the non-thermal Universe, delving into the mechanisms of production and absorption that govern the gamma-ray emis- sion. I also introduce the MAGIC telescopes, from which the bulk of results in this thesis are obtained. Other detection techniques, such as those used by the HAWC Observatory and the Fermi-LAT satellite, are also introduced as results from both of them are used in the discussion of galactic sources included in this thesis. The scientific achievements are encompassed in Part II and Part III. In the former, I discuss results from the three best microquasar candidates to emit Very-High-Energy (VHE) gamma rays: Cygnus X-1, Cygnus X-3 and V404 Cygni. I investigate them making use of MAGIC data during long-term campaigns or under flaring periods. Furthermore, in order to complement results at lower energies, I analyze Fermi-LAT data of Cygnus X-1, leading to the detection of the system in the High Energy (HE) regime. This constitutes the first firmly gamma-ray detection on a Black Hole (BH) binary system. Part III is focused on the study of PWNe. I analyze five sources of this type and set the results in the context of the TeV PWN population study performed by the High Energy Stereoscopic System (H.E.S.S.) Collaboration. Along with these results, I discuss the importance of the target photon field together with characteristic features of the pulsars hosted by these PWNe to emit gamma rays. In this thesis, I also present the first joint work between the HAWC Observatory and MAGIC, which opens the door to future synergy projects. vii In Part IV, I present the technical work performed during my thesis for the future Cherenkov Telescope Array (CTA) instrument. I focus on the camera hardware for the Large Size Telescope (LST), working on the Quality Control (QC) for several subsystems, among which the Photomultiplier Tubes (PMTs), power supplies and trigger mezzanines stand out. Finally, I summarize all the aforementioned results in a conclusion chapter. All the work developed during my thesis led to seven publications in scientific journals: two of them already published, two accepted by the corresponding journal and three currently under the revision of MAGIC and all implicated collaborations. viii Resumen A lo largo de toda nuestra historia, los seres humanos nos hemos esforzado por descifrar los misterios con los que el Universo nos desaf´ıa. En nuestros humildes comienzos, esta tarea era realizada con nuestros ojos desnudos, mirando las estrel- las y los planetas y preguntandonos´ que´ tan lejos estaban y como´ se mov´ıan en el cielo nocturno. Durante muchos siglos, solo´ el Universo visible fue accesible para nosotros, pero se obtuvieron logros extraordinarios a pesar de las limitadas her- ramientas: descubrimos, por ejemplo, que nuestro planeta no era el centro del Uni- verso, gracias a las observaciones de Nicolaus Copernicus y su modelo heliocentrico.´ Desde la epoca´ de Copernicus hasta ahora, el desarrollo de nuevas tecnolog´ıas y el avance de nuestra propia comprension´ del Cosmos, nos ha permitido desentranar˜ mucho enigmas. Afortunadamente, esta curiosidad natural que nos lleva a mejorar nunca termina, y nos enfretamos a nuevas preguntas que desaf´ıan nuestra capaci- dad como cient´ıficos. En la presente tesis, me centro en una pequena˜ fraccion´ de esta ciencia: la astronom´ıa de rayos gamma. Dentro de este campo, estudio la acel- eracion´ de part´ıculas y los mecanismos de produccion´ de rayos gamma en los jets relativistas de los denominados microcuasares´ y en shocks producidos en pleriones. En la Parte I de la tesis, presento una introduccion´ al Universo no termico,´ profun- dizando en los mecanismos de produccion´ y absorcion´ que gobiernan la emision´ de rayos gamma. Tambien´ introduzco los telescopios MAGIC, de los cuales se obtiene la mayor parte de los resultados de esta tesis. Otras tecnicas´ de deteccion,´ como las empleadas en el Observatorio HAWC o por el satelite´ Fermi-LAT, son igual- mente presentadas dado que sus resultados son empleados en la discusion´ de fuentes galacticas´ incluidas en esta tesis. Los logros cient´ıficos estan´ incluidos en la Parte II y Parte II. En el primera, dis- cuto los resultados de los tres mejores candidatos microcuasares´ para emitir rayos gamma a muy altas energ´ıas: Cygnus X-1, Cygnus X-3 y V404 Cygni. Investigo to- dos ellos haciendo uso de los datos de MAGIC durante campanas˜ observacionales de larga duracion´ o durante periodos de alta actividad. Por otra parte, con el fin de complementar los resultados a energ´ıas mas´ bajas, analizo los datos de Fermi-LAT de Cygnus X-1, lo cual condujo a la deteccion´ del sistema en el regime´ de altas en- erg´ıas. Esto constituye la primer deteccion´ firme de rayos gamma a altas energ´ıas de un sistema binario compuesto por un agujero negro. La Parte III se centra en el estudio de pleriones. Analizo cinco fuentes pertenecientes a esta clase y contex- tualizo los resultados dentro del estudio de poblacion´ de pleriones realizado por la Colaboracion´ H.E.S.S.. Haciendo uso de estos resultados, se discute la importancia ix de la densidad de fotones en el medio circundante junto con las caracter´ısticas de los pulsares´ alojado por estos pleriones para la emision´ de rayos gamma. En esta tesis, tambien´ presento el primer trabajo conjunto entre el Observatorio HAWC y MAGIC, que abre las puertas a futuros proyectos en sinergia. La Parte IV incluye el trabajo tecnico´ realizado durante mi tesis con el futuro CTA. Este trabajo esta´ centrado en el hardware de la camara´ de los telescopios de gran tamano˜ (LST, por sus siglas en ingles)´ del futuro instrumento CTA, que incluye el control de calidad de varios subsistemas, entre los que descatan los fotomultipli- cadores, las fuentes de alimentacion´ y el sistema de trigger. Finalmente, resumo todos los anteriormente mencionados resultados en un cap´ıtulo de conclusiones. Todo el trabajo desarrollado durante mi tesis dio lugar a siete pub- licaciones en revistas cient´ıficas: dos ya publicadas, dos aceptadas por la correspon- diente revista y tres actualmente bajo revision´ de la Colaboracion´ de MAGIC y otras colaboraciones implicadas. x Contents Contents ix List of Figures xv List of Tables xxi I Introduction to the non-thermal Universe 1 1 Cosmic rays and gamma-ray astrophysics 3 1.1 Cosmic rays . 4 1.1.1 Spectrum . 5 1.1.2 Cosmic ray acceleration . 5 1.2 Gamma-ray astrophysics . 7 1.2.1 Gamma-ray production .
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