The IceCube Neutrino Observatory has reported the observation of 35 neutrino events above 30 TeV with evidence for an astrophysical neutrino flux using data collected from May 2010 to May 2013. These events provide the first high-energy astrophysical neutrino flux ever observed. The sources of these events are currently unknown. IceCube has looked for correlations between these events and a list of TeV photon sources including a catalog of 36 galactic sources and 42 extragalactic sources, correlations with the galactic plane and center, and spatial and temporal clustering. These searches have shown no significant correlations. The isotropic distribution of the event directions gives indications that the events could be extragalactic in nature and therefore may originate in the same processes that generate ultra-high-energy cosmic rays (UHECRs). The sources of these UHECRs are still unknown; however, gamma-ray bursts (GRBs) have been proposed as one possible source class. By determining the source of these high-energy neutrinos, it may be possible to determine the sources of UHECRs as well. This study is a search for directional and temporal correlation between 856 GRBs and the astrophysical neutrino flux observed by IceCube. Nearly 10,000 expanding time windows centered on the earliest reported time of the burst were examined. The time windows start at ±10 s and extend to ±15 days. We find no evidence of correlations for these time windows and set an upper limit on the fraction of the astrophysical flux that can be attributed to the observed GRBs as a function of the time window. GRBs can contribute at most 12% of the astrophysical neutrino flux if the neutrino-GRB correlation time is less than ≈20 hours, and no more than 38% of the astrophysical neutrino flux can be attributed to the known GRBs at time scales up to 15 days. We conclude that GRBs observable by satellites are not solely responsible for IceCube’s astrophysical neutrino flux, even if very long correlation time scales are assumed.

This thesis presents the study of four aspects of high energy astronomy.The first part of my thesis is dedicated to an aspect of instrument development for imaging atmospheric Cherenkov telescopes, namely the Level 2 trigger system of the High Energy Stereoscopic System (H.E.S.S.). My work on the project focused on the algorithm development and the Monte Carlo simulations of the trigger system and overall instrument (Moudden, Barnacka, Glicenstein et al. 2011a; Moudden, Venault, Barnacka et al. 2011b). The hardware implementation of the system is described andits expected performances are then evaluated. The H.E.S.S. array has been used to observe the blazar PKS 1510-089.The second part of my thesis deals with the data analysis and modeling of broad-band emission of this particular blazar. In part II of my thesis, I am presenting the analysis of the H.E.S.S. data: the light curve and spectrum of PKS 1510-089, together with the FERMI data and a collection of multi-wavelength data obtained with various instruments. I am presenting the model of PKS 1510-089 observations carried out during a flare recorded by H.E.S.S.. The model is based on a single zone internal shock scenario.The third part of my thesis deals with blazars observed by the FERMI-LAT, but from the point of view of other phenomena: a strong gravitational lensing. This part of my thesis shows the first evidence for gravitational lensing phenomena in high energy gamma-rays. This evidence comes from the observation of a gravitational lens system induced echo in the light curve of the distant blazar PKS 1830-211. Traditionalmethods for the estimation of time delays in gravitational lensing systems rely on the cross-correlation of the light curves from individual images. In my thesis, I used 300 MeV-30 GeV photons detected by the Fermi-LAT instrument. The FERMI-LAT instrument cannot separate the images of known lenses. The observed light curve is thus the superposition of individual image light curves. The FERMI-LAT instrument has the advantage of providing long, evenly spaced, time series with very low photonnoise. This allows to use directly Fourier transform methods. A time delay between the two compact images of PKS 1830-211 has been searchedfor both by the autocorrelation method and a new method: the "double power spectrum". The double power spectrum shows a 4.2 σ evidence for a time delay of 27.1±0.6 days (Barnacka et al. 2011), consistent with the results from Lovell et al. (1998) and Wiklind & Combes (2001).The last part of my thesis concentrates on another lensing phenomena called "femtolensing". The search for femtolensing effects has been used to derive limits on the primordial black holes abundance. The abundance of primordial black holes is currently significantly constrained in a wide range of masses. The weakest limits are established for the small mass objects, where the small intensity of the associated physical phenomenon provides a challenge for current experiments. I have usedgamma-ray bursts with known redshifts detected by the FERMI Gamma-ray Burst Monitor (GBM) to search for the femtolensing effects caused by compact objects. The lack of femtolensing detection in the GBM data provides new evidence that primordial black holes in the mass range 5 × 10^17 - 10^20 g do not constitute a major fraction of dark matter (Barnacka et al. 2012). My Ph.D. studies have been carried out jointly between the Nicolaus Copernicus Astronomical Center of the Polish Academy of Sciences, in Warsaw in Poland and the IRFU institute of the Commissariat à l'énergie atomique et aux énergies alternatives(CEA) Saclay in France.

Das IceCube Neutrinoteleskop hat im Jahr 2013 erstmals einen isotropen, quasi-diffusen astrophysikalischen Neutrinoflusses detektiert. Dieser Fluss kann jedoch bisher keiner astrophysikalischen Quellklasse zugeordnet werden. Um nach kurzlebigen Neutrinoquellen zu suchen, wurde 2008 das optische und Röntgen-Nachfolgebeobachtungsprogramm des IceCube Detektors eingerichtet. Es sucht nach zwei oder mehr Neutrinoereignissen, die von einer Punkquelle stammen könnten und innerhalb von 100s detektiert werden. Ein solches Signal wird unter anderem von langen oder kurzen Gammastrahlungsblitzen (GRBs) erwartet oder von verwandten Objekten wie leuchtschwachen GRBs oder Supernovae mit relativistischen Jets. Die Alarmraten des Nachfolgebeobachtungsprogramms sind jedoch niedrig und bieten bisher keine Hinweise für die Existenz von kurzlebigen Neutrinoquellen. Das Nachfolgebeobachungsprogramm hat bisher nur ein einziges Neutrinotriplet detektiert, das der Auslöser für eine umfassende Beobachtungskampagne war. In den optischen, Röntgen- und Gammastrahlungsbeobachtungen wurde keine wahrscheinliche Neutrinoquelle identifiziert und eine Supernova oder ein heller GRB können ausgeschlossen werden. Das Neutrinotriplet kann entweder eine zufällige Koinzidenz von Untergrundereignissen sein (alle 13.7 Jahre erwartet) oder es kann von einer leuchtschwachen oder besonders schnell verblassenden Quelle stammen. Die niedrige Rate von Neutrinomultipletts stellt außerdem eine obere Schranke auf die Helligkeit von kurzlebigen Neutrinoquellen dar. Seltene Quellen mit lokalen Raten von < 3e-8 – 10e-5 Mpc^-3 Jahr^-1 können nicht den gesammten Fluss erzeugen, ohne die detektierte Anzahl Multipletts zu überschreiten. Der Fluss von GRBs ist dadurch auf 5-30% des astrophysikalischen Flusses beschränkt. Falls 1% aller Kernkollaps-Supernovae einen Jet besitzen, der auf die Erde zeigt, so können sie 40-100% des Flusses erzeugen und ihre durchschnittliche Neutrinohelligkeit ist <3e51erg. / The IceCube neutrino observatory first detected and isotropic, quasi-diffuse astrophysical neutrino flux in 2013. However, this flux can so far not be associated with an astrophysical source class. To search for short-lived neutrino sources, the optical and X-ray follow-up program was established in 2008. It searches for two or more neutrino events that might origin from a point source and are detected within 100s. Such a signal is expected from long or short gamma-ray bursts (GRBs) or from related objects like low-luminosity GRBs or supernovae with choked jets. The alert rates of the follow-up program are however low, such that they do not provide evidence for the existence of short-lived neutrino sources. So far the follow-up program has only detected a one neutrino triplet, which triggered an extensive follow-up campaign. No likely neutrino source was detected in the collected optical, X-ray and gamma-ray observations and the presence of a supernova or a bright GRB can be excluded. The neutrino triplet can either be a chance coincidence of background events (expected every 13.7 years) or is can originate from a faint or quickly fading astrophysical source. The low rate of neutrino multiplets moreover provides an upper limit on the luminosity of short-lived neutrino sources. Rare sources with local rates of < 3e-8 – 10e-5 Mpc^-3 yr^-1 cannot produce the complete fluc without producing too many neutrino multiplets. This limits the contribution of GRBs to 5-30% of the astrophysical flux. If 1% of all core-collapse supernovae have a jet that is pointed at Earth, they can emit up to 40-100% of the flux and their average neutrino luminosity is <3e51erg.

La présente thèse porte sur quatre aspects différents de l’astronomie des hautes énergies.La première partie de ma thèse est dédiée à un développement instrumental pour les télescopes Cherenkov imageurs, le système de déclenchement de niveau 2 du télescope de 28 mètres du réseau H.E.S.S. (High Energy Stereoscopic System). Mon travail s’est focalisé sur l’invention d’algorithmes et les simulations Monte-Carlo du système de déclenchement, ainsi que la comparaison de la reconstruction au niveau de la carte de déclenchement à la reconstruction ”hors-ligne” (Moudden,Barnacka, Glicenstein et al. 2011a; Moudden, Venault, Barnacka et al. 2011b). Je décris le système et j’évalue ses performances.Le réseau H.E.S.S. a observé le blazar PKS1510-089. La deuxième partie de ma thèse traite de l’analyse des données et la modélisation de l’émission large bande de ce blazar. C’est un exemple de quasar radio à spectre plat (FSRQ), pour lequel il n’est attendu aucune émission aux très hautes énergiesJ’ai modélisé les données observées pendant un "flare” de PKS1510-089. Ce modèle est basé sur un scénario de choc interne à une zone.Le troisième chapitre de ma thèse est une étude d’un autre phénomène affectant potentiellement les blazars observés par FERMI-LAT: l’effet de lentille gravitationnelle fort. Cette partie de ma thèse montre le premier indice de présence d’un effet de lentille gravitationnelle dans le domaine des photons de haute énergie. Cet indice provient de l’observation d’un écho dans la courbe de lumière du blazar distant PKS1830-211, qui est une lentille gravitationnelle connue. Les méthodes d’estimation des retards temporels dans les systèmes de lentille gravitationnelles reposent sur la corrélation croisée des courbes de lumière individuelles. Dans l’analyse présentée dans cette thèse, j’ai utilisé des photons de 300 MeV à 30 GeV détectés par l’instrument FERMI-LAT. L’instrument FERMI-LAT ne peut pas séparer spatialement les images des lentilles gravitationnelles fortes connues. La courbe de lumière observée est donc la superposition des courbes de lumière des images individuelles. Les données du FERMI-LAT ont l’avantage d’être des séries temporelles régulièrement espacées,avec un bruit de photons très bas. Cela permet d’utiliser directement les méthodes de transformées de Fourier. Un retard temporel entre les images compactes de PKS1830-211 a été recherché par deux méthodes : une méthode d’auto-corrélation et la méthode du ”double spectre”. La méthode du double spectre fournit un signal de 27 ± 0.6jours (statistique) avec une significativité de 4.2 σ. Ce résultat est compatible avec ceux de Lovell et al (1998) et Wiklind et Combes (2001).La dernière partie de ma thèse est consacrée à un effet de lentille différent, le ”femtolensing”. La recherche d’effets de femtolensing a été utlisée pour obtenir des limites sur l’abondance de trous noirs primordiaux. Celle-ci a été contrainte de manière significative dans un large domaine de masses. Les limites les moins contraignantes ont été établies pour les objets de faible masse, pour lesquels la détection représente un défi expérimental. J’ai utilisé les sursauts gamma de redshift connus d´etectés par le Fermi Gamma Ray Burst Monitor (GBM) pour rechercher d’éventuels effets de femtolensing produits par des objets compacts sur la ligne de visée. L’absence de ces effets de femtolensing montre que des trous noirs primordiaux de masse comprises entre 5×10^17 et 10^20 g ne constituent pas une fraction importante de la matière noire. J’ai effectué mes études de thèse en co-tutelle entre le Centre Astronomique Nicolaus Copernicus de l’académie des sciences polonaise, à Varsovie et l’Institut de Recherches sur les Lois fondamentales de l’Univers du CNRS à Saclay, en France. / This thesis presents the study of four aspects of high energy astronomy.The first part of my thesis is dedicated to an aspect of instrument development for imaging atmospheric Cherenkov telescopes, namely the Level 2 trigger system of the High Energy Stereoscopic System (H.E.S.S.). My work on the project focused on the algorithm development and the Monte Carlo simulations of the trigger system and overall instrument (Moudden, Barnacka, Glicenstein et al. 2011a; Moudden, Venault, Barnacka et al. 2011b). The hardware implementation of the system is described andits expected performances are then evaluated. The H.E.S.S. array has been used to observe the blazar PKS 1510-089.The second part of my thesis deals with the data analysis and modeling of broad-band emission of this particular blazar. In part II of my thesis, I am presenting the analysis of the H.E.S.S. data: the light curve and spectrum of PKS 1510-089, together with the FERMI data and a collection of multi-wavelength data obtained with various instruments. I am presenting the model of PKS 1510-089 observations carried out during a flare recorded by H.E.S.S.. The model is based on a single zone internal shock scenario.The third part of my thesis deals with blazars observed by the FERMI-LAT, but from the point of view of other phenomena: a strong gravitational lensing. This part of my thesis shows the first evidence for gravitational lensing phenomena in high energy gamma-rays. This evidence comes from the observation of a gravitational lens system induced echo in the light curve of the distant blazar PKS 1830-211. Traditionalmethods for the estimation of time delays in gravitational lensing systems rely on the cross-correlation of the light curves from individual images. In my thesis, I used 300 MeV-30 GeV photons detected by the Fermi-LAT instrument. The FERMI-LAT instrument cannot separate the images of known lenses. The observed light curve is thus the superposition of individual image light curves. The FERMI-LAT instrument has the advantage of providing long, evenly spaced, time series with very low photonnoise. This allows to use directly Fourier transform methods. A time delay between the two compact images of PKS 1830-211 has been searchedfor both by the autocorrelation method and a new method: the “double power spectrum”. The double power spectrum shows a 4.2 σ evidence for a time delay of 27.1±0.6 days (Barnacka et al. 2011), consistent with the results from Lovell et al. (1998) and Wiklind & Combes (2001).The last part of my thesis concentrates on another lensing phenomena called ”femtolensing”. The search for femtolensing effects has been used to derive limits on the primordial black holes abundance. The abundance of primordial black holes is currently significantly constrained in a wide range of masses. The weakest limits are established for the small mass objects, where the small intensity of the associated physical phenomenon provides a challenge for current experiments. I have usedgamma-ray bursts with known redshifts detected by the FERMI Gamma-ray Burst Monitor (GBM) to search for the femtolensing effects caused by compact objects. The lack of femtolensing detection in the GBM data provides new evidence that primordial black holes in the mass range 5 × 10^17 – 10^20 g do not constitute a major fraction of dark matter (Barnacka et al. 2012). My Ph.D. studies have been carried out jointly between the Nicolaus Copernicus Astronomical Center of the Polish Academy of Sciences, in Warsaw in Poland and the IRFU institute of the Commissariat à l’énergie atomique et aux énergies alternatives(CEA) Saclay in France.

No description available.

Gamma Ray Burst (GRB) are very bright cosmological explosions signalling the catastrophic formation of a black hole. Therefore, they act like real light beacons that could be detected through-out the Universe and be used as probes to study the contents and phases of the early Universe. However, only a handful sample is known so far. This is for two reasons: instrumental biases that may prevent their detection and the difficulty to find a near Infrared counterpart preventing their redshift measurements. The wide-field trigger camera ECLAIRs to-fly on-board the Space-based multi-band Variable Object Monitor (SVOM) mission will detect γ-/X-ray transients down to energies of 4 keV, as well as creating an alert for multi-wavelength/messenger follow-ups. My study focuses on analysing how ECLAIRs will detect GRBs, and more particularly high-redshift GRBs, based on a well-selected sample of GRBs with redshift measurement associated (see Section 2). Studying how ECLAIRs will see them may help identifying possible instrument biases as well as common observational characteristics for such GRBs that may be used in turn to recognise such special GRBs once SVOM will be launched. Using software tools developed within the ECLAIRs collaboration, I built an end-to-end simulator which I used to simulate the detection by ECLAIRs of the GRBs in the sample at their original redshift and higher redshifts (up to z = 15). I implemented a suited version of the count-rate trigger on-board ECLAIRs to assess the detectability of these bursts, and I retrieved their duration over the background when detected (see Section 2). The analysis shows good performance for detecting high-redshift GRBs in the centre of the Field of View (fully-coded), but significantly reduced, in comparison to other GRBs, for partially-coded detection. 5 of the GRBs with z &gt; 3.83 present a successful detection up to at least z = 15 (see Section 3). The retrieved rest-frame duration of a GRB remains constant for several redshifts in the simulations if the detected burst did not present a low-flux emission in their lightcurve, which is common for high redshift GRBs. On the other hand, if the original lightcurve of a burst presents this low-flux emission, it becomes buried in noise when simulating it at higher redshifts. This confirms the tip-of-the-iceberg detection bias which depends on the lightcurve burst morphology, and it may explain why the current sample seems to present lower burst durations at higher redshifts.