61 research outputs found
Electrical properties and non-volatile memory effect of the [Fe(HB(pz)3)2] spin crossover complex integrated in a microelectrode device
We report on the deposition of thin films of the [Fe(HB(pz)3)2] (pz = pyrazolyl) molecular spin crossover complex by thermal evaporation. By means of impedance measurements and Raman microspectroscopy, we show that the films maintain the structure and properties of the bulk material. The conductivity of the films decreases by ca. 2 orders of magnitude when the freshly deposited compound goes through a first (irreversible) thermal phase change above ca. 380 K. This property can be exploited as a non-volatile (read-only) memory effect
Electroweak phase transitions in multi-Higgs models: the case of Trinification-inspired THDSM
The rich vacuum structure of multi-Higgs extensions of the Standard Model (SM)
may have interesting cosmological implications for the electroweak phase transition (EWPT).
As an important example of such class of models, we consider a particularly simple low-
energy SM-like limit of a recently proposed Grand-Unified Trinification model with the scalar
sector composed of two Higgs doublets and a complex singlet and with a global U(1) family
symmetry. The fermion sector of this model is extended with a family of vector-like quarks
which enhances CP violation. With the current study, we aim at exploring the generic vacuum
structure and uncovering the features of the EWPT in this model relevant for cosmology.
We show the existence of different phase transition patterns providing strong departure from
thermal equilibrium. Most of these observations are not specific to the considered model and
may generically be expected in other multi-Higgs extensions of the SM.publishe
Direct microcontact printing of oligonucleotides for biochip applications
BACKGROUND: A critical step in the fabrication of biochips is the controlled placement of probes molecules on solid surfaces. This is currently performed by sequential deposition of probes on a target surface with split or solid pins. In this article, we present a cost-effective procedure namely microcontact printing using stamps, for a parallel deposition of probes applicable for manufacturing biochips. RESULTS: Contrary to a previous work, we showed that the stamps tailored with an elastomeric poly(dimethylsiloxane) material did not require any surface modification to be able to adsorb oligonucleotides or PCR products. The adsorbed DNA molecules are subsequently printed efficiently on a target surface with high sub-micron resolution. Secondly, we showed that successive stamping is characterized by an exponential decay of the amount of transferred DNA molecules to the surface up the 4(th )print, then followed by a second regime of transfer that was dependent on the contact time and which resulted in reduced quality of the features. Thus, while consecutive stamping was possible, this procedure turned out to be less reproducible and more time consuming than simply re-inking the stamps between each print. Thirdly, we showed that the hybridization signals on arrays made by microcontact printing were 5 to 10-times higher than those made by conventional spotting methods. Finally, we demonstrated the validity of this microcontact printing method in manufacturing oligonucleotides arrays for mutations recognition in a yeast gene. CONCLUSION: The microcontact printing can be considered as a new potential technology platform to pattern DNA microarrays that may have significant advantages over the conventional spotting technologies as it is easy to implement, it uses low cost material to make the stamp, and the arrays made by this technology are 10-times more sensitive in term of hybridization signals than those manufactured by conventional spotting technology
Arrays of Nano-Electromechanical Biosensors Functionalized by Microcontact Printing
The biofunctionalization of nanoelectromechanical structures is critical for
the development of new classes of biosensors displaying improved performances
and higher-level of integration. We propose a modified microcontact printing
method for the functionalization and passivation of large arrays of
nanocantilevers in a single, self-aligned step. Using fluorescence microscopy
and resonant frequency measurements, we demonstrate (1) the bioactivity and the
anti-fouling property of deposited antibodies and BSA molecules and (2) the
preservation of the nanostructures' mechanical integrity.Comment: 20 pages, 5 figure
Pressure and Temperature Spin Crossover Sensors with Optical Detection
Iron(II) spin crossover molecular materials are made of coordination centres switchable between two states by temperature, pressure or a visible light irradiation. The relevant macroscopic parameter which monitors the magnetic state of a given solid is the high-spin (HS) fraction denoted nHS, i.e., the relative population of HS molecules. Each spin crossover material is distinguished by a transition temperature T1/2 where 50% of active molecules have switched to the low-spin (LS) state. In strongly interacting systems, the thermal spin switching occurs abruptly at T1/2. Applying pressure induces a shift from HS to LS states, which is the direct consequence of the lower volume for the LS molecule. Each material has thus a well defined pressure value P1/2. In both cases the spin state change is easily detectable by optical means thanks to a thermo/piezochromic effect that is often encountered in these materials. In this contribution, we discuss potential use of spin crossover molecular materials as temperature and pressure sensors with optical detection. The ones presenting smooth transitions behaviour, which have not been seriously considered for any application, are spotlighted as potential sensors which should stimulate a large interest on this well investigated class of materials
Les superbulles et l'origine des rayons cosmiques
It has been known for more than a century that the interstellar medium is full of charged particles called cosmic rays. These particles are crucial agents in the galactic ecosystem. Not only do they influence the properties of space plasmas and magnetic fields, they also impact the gas dynamics, drive the evolution of molecular clouds and regulate the formation of the stars. Yet, there is still no definite answer to the question of their sources. Given the gigantic energies that some of these particles carry when they impact the Earth atmosphere, they are much likely produced in the most energetic astrophysical systems of the galaxy such as massive stars eventually exploding as supernovae. During the last decades, the supernova remnant shocks have indeed been proved to efficiently accelerate particles up to high energies. Although appealing from a global energetic point of view, this scenario of cosmic ray production is nowadays challenged by a number of arguments, including the difficulty to account for the cosmic rays of very high energies as well as the peculiarities of the cosmic ray spectrum measured on Earth. On the other hand, most of the massive stars which end their lives as supernovae are believed to be born within clusters formed inside dense molecular clouds. During their lives, the clustered stars collectively carve galactic-scale cavities, called superbubbles, in their parent environment. The stellar winds and subsequent supernova explosions deposit a large amount of mechanical, thermal and turbulent energy within these superbubbles, which makes them appealing candidates as cosmic ray sources. However, the acceleration of particles in these environments has been scarcely considered. This thesis therefore aims at reviewing the relevant fundamental mechanisms of acceleration in superbubbles in order to provide an investigation by means of semi-analytical modellings derived from first principles. Collective effects such as shock collisions and successive events of particle reacceleration are discussed. A self-consistent model accounting for the non-linear feedback of the particles on the environment is described. The hydromagnetic turbulence, the multiple supernovae and the stellar winds are found to be efficient sources of cosmic rays. The spectrum of the accelerated particles is not only influenced by the collective effects and the propagation in the bubble interior, but also by the magnetised supershell which surrounds the bubble and the intermittency of the mechanical power delivered by the stars. The overall contribution of galactic star clusters and superbubbles to the cosmic ray spectrum is eventually discussed, as well as recent gamma-ray observations.Il a Ă©tĂ© dĂ©couvert il y a plus d'un siĂšcle que le milieu interstellaire est rempli de particules chargĂ©es appelĂ©es rayons cosmiques. Ces particules sont des composantes de premier-plan dans l'Ă©cosystĂšme galactique. Non seulement elles influencent les propriĂ©tĂ©s des plasmas et des champs magnĂ©tiques, mais elles impactent Ă©galement la dynamique des gaz, rĂ©gissent l'Ă©volution des nuages molĂ©culaires et rĂ©gulent la formation des Ă©toiles. Cependant, la question de leurs sources reste sans rĂ©ponse dĂ©finitive. Les Ă©nergies gigantesques que certaines de ces particules atteignent lorsqu'elles impactent l'atmosphĂšre terrestre suggĂšrent qu'elles doivent ĂȘtre produites dans les systĂšmes astrophysiques les plus puissants de la galaxie, comme les Ă©toiles massives qui finissent par exploser en supernovae. Au cours des derniĂšres dĂ©cennies, il a Ă©tĂ© dĂ©montrĂ© que les vestiges de supernovae accĂ©lĂšrent en effet des particules. Bien que sĂ©duisant d'un point de vue Ă©nergĂ©tique, ce scĂ©nario de production de rayons cosmiques est aujourd'hui Ă©branlĂ© par un certain nombre d'arguments, incluant la difficultĂ© de rendre compte des rayons cosmiques de trĂšs hautes Ă©nergies ainsi que des particularitĂ©s du spectre mesurĂ© sur Terre. D'un autre cĂŽtĂ©, la plupart des Ă©toiles massives qui explosent en supernovae Ă la fin de leur vie sont supposĂ©es naĂźtre au sein d'amas formĂ©s Ă l'intĂ©rieur de nuages molĂ©culaires denses. Durant leur vie, les Ă©toiles creusent autour des amas des cavitĂ©s qui atteignent des dimensions galactiques et que l'on appelle des superbulles. Les vents stellaires et les explosions de supernovae dĂ©posent une grande quantitĂ© d'Ă©nergie mĂ©canique, thermique et turbulente Ă l'intĂ©rieur de ces cavitĂ©s, ce qui en font des candidates de choix comme sources du rayonnement cosmique. Pourtant, l'accĂ©lĂ©ration des particules dans ces environnements a Ă©tĂ© rarement considĂ©rĂ©e. Cette thĂšse a donc pour but de rĂ©capituler les mĂ©canismes d'accĂ©lĂ©rations fondamentaux supposĂ©s agir Ă l'intĂ©rieur des superbulles, afin de produire des modĂšles semi-analytiques dĂ©rivĂ©s d'Ă©quations fondamentales. Des effets collectifs comme les collisions entre ondes de choc et les rĂ©accĂ©lĂ©rations successives des particules confinĂ©es sont discutĂ©s. Un modĂšle auto-consistant, prenant en compte la rĂ©ponse non-linĂ©aire des particules sur leur environnement, est dĂ©crit. Il est montrĂ© que la turbulence hydromagnĂ©tique, les multiples supernovae et les vents stellaires produisent efficacement des rayons cosmiques. Le spectre des particules accĂ©lĂ©rĂ©es est non seulement influencĂ© par les effets collectifs et la propagation dans l'intĂ©rieur de la bulle, mais aussi par la coquille magnĂ©tisĂ©e qui dĂ©limite la bulle et le caractĂšre intermittent de la puissance mĂ©canique dĂ©livrĂ©e par les Ă©toiles. La contribution globale des amas stellaires et des superbulles galactiques au spectre des rayons cosmiques est finalement discutĂ©e, ainsi que des observations rĂ©centes en rayons gammas
Les superbulles et l'origine des rayons cosmiques
It has been known for more than a century that the interstellar medium is full of charged particles called cosmic rays. These particles are crucial agents in the galactic ecosystem. Not only do they influence the properties of space plasmas and magnetic fields, they also impact the gas dynamics, drive the evolution of molecular clouds and regulate the formation of the stars. Yet, there is still no definite answer to the question of their sources. Given the gigantic energies that some of these particles carry when they impact the Earth atmosphere, they are much likely produced in the most energetic astrophysical systems of the galaxy such as massive stars eventually exploding as supernovae. During the last decades, the supernova remnant shocks have indeed been proved to efficiently accelerate particles up to high energies. Although appealing from a global energetic point of view, this scenario of cosmic ray production is nowadays challenged by a number of arguments, including the difficulty to account for the cosmic rays of very high energies as well as the peculiarities of the cosmic ray spectrum measured on Earth. On the other hand, most of the massive stars which end their lives as supernovae are believed to be born within clusters formed inside dense molecular clouds. During their lives, the clustered stars collectively carve galactic-scale cavities, called superbubbles, in their parent environment. The stellar winds and subsequent supernova explosions deposit a large amount of mechanical, thermal and turbulent energy within these superbubbles, which makes them appealing candidates as cosmic ray sources. However, the acceleration of particles in these environments has been scarcely considered. This thesis therefore aims at reviewing the relevant fundamental mechanisms of acceleration in superbubbles in order to provide an investigation by means of semi-analytical modellings derived from first principles. Collective effects such as shock collisions and successive events of particle reacceleration are discussed. A self-consistent model accounting for the non-linear feedback of the particles on the environment is described. The hydromagnetic turbulence, the multiple supernovae and the stellar winds are found to be efficient sources of cosmic rays. The spectrum of the accelerated particles is not only influenced by the collective effects and the propagation in the bubble interior, but also by the magnetised supershell which surrounds the bubble and the intermittency of the mechanical power delivered by the stars. The overall contribution of galactic star clusters and superbubbles to the cosmic ray spectrum is eventually discussed, as well as recent gamma-ray observations.Il a Ă©tĂ© dĂ©couvert il y a plus d'un siĂšcle que le milieu interstellaire est rempli de particules chargĂ©es appelĂ©es rayons cosmiques. Ces particules sont des composantes de premier-plan dans l'Ă©cosystĂšme galactique. Non seulement elles influencent les propriĂ©tĂ©s des plasmas et des champs magnĂ©tiques, mais elles impactent Ă©galement la dynamique des gaz, rĂ©gissent l'Ă©volution des nuages molĂ©culaires et rĂ©gulent la formation des Ă©toiles. Cependant, la question de leurs sources reste sans rĂ©ponse dĂ©finitive. Les Ă©nergies gigantesques que certaines de ces particules atteignent lorsqu'elles impactent l'atmosphĂšre terrestre suggĂšrent qu'elles doivent ĂȘtre produites dans les systĂšmes astrophysiques les plus puissants de la galaxie, comme les Ă©toiles massives qui finissent par exploser en supernovae. Au cours des derniĂšres dĂ©cennies, il a Ă©tĂ© dĂ©montrĂ© que les vestiges de supernovae accĂ©lĂšrent en effet des particules. Bien que sĂ©duisant d'un point de vue Ă©nergĂ©tique, ce scĂ©nario de production de rayons cosmiques est aujourd'hui Ă©branlĂ© par un certain nombre d'arguments, incluant la difficultĂ© de rendre compte des rayons cosmiques de trĂšs hautes Ă©nergies ainsi que des particularitĂ©s du spectre mesurĂ© sur Terre. D'un autre cĂŽtĂ©, la plupart des Ă©toiles massives qui explosent en supernovae Ă la fin de leur vie sont supposĂ©es naĂźtre au sein d'amas formĂ©s Ă l'intĂ©rieur de nuages molĂ©culaires denses. Durant leur vie, les Ă©toiles creusent autour des amas des cavitĂ©s qui atteignent des dimensions galactiques et que l'on appelle des superbulles. Les vents stellaires et les explosions de supernovae dĂ©posent une grande quantitĂ© d'Ă©nergie mĂ©canique, thermique et turbulente Ă l'intĂ©rieur de ces cavitĂ©s, ce qui en font des candidates de choix comme sources du rayonnement cosmique. Pourtant, l'accĂ©lĂ©ration des particules dans ces environnements a Ă©tĂ© rarement considĂ©rĂ©e. Cette thĂšse a donc pour but de rĂ©capituler les mĂ©canismes d'accĂ©lĂ©rations fondamentaux supposĂ©s agir Ă l'intĂ©rieur des superbulles, afin de produire des modĂšles semi-analytiques dĂ©rivĂ©s d'Ă©quations fondamentales. Des effets collectifs comme les collisions entre ondes de choc et les rĂ©accĂ©lĂ©rations successives des particules confinĂ©es sont discutĂ©s. Un modĂšle auto-consistant, prenant en compte la rĂ©ponse non-linĂ©aire des particules sur leur environnement, est dĂ©crit. Il est montrĂ© que la turbulence hydromagnĂ©tique, les multiples supernovae et les vents stellaires produisent efficacement des rayons cosmiques. Le spectre des particules accĂ©lĂ©rĂ©es est non seulement influencĂ© par les effets collectifs et la propagation dans l'intĂ©rieur de la bulle, mais aussi par la coquille magnĂ©tisĂ©e qui dĂ©limite la bulle et le caractĂšre intermittent de la puissance mĂ©canique dĂ©livrĂ©e par les Ă©toiles. La contribution globale des amas stellaires et des superbulles galactiques au spectre des rayons cosmiques est finalement discutĂ©e, ainsi que des observations rĂ©centes en rayons gammas
Les superbulles et l'origine des rayons cosmiques
It has been known for more than a century that the interstellar medium is full of charged particles called cosmic rays. These particles are crucial agents in the galactic ecosystem. Not only do they influence the properties of space plasmas and magnetic fields, they also impact the gas dynamics, drive the evolution of molecular clouds and regulate the formation of the stars. Yet, there is still no definite answer to the question of their sources. Given the gigantic energies that some of these particles carry when they impact the Earth atmosphere, they are much likely produced in the most energetic astrophysical systems of the galaxy such as massive stars eventually exploding as supernovae. During the last decades, the supernova remnant shocks have indeed been proved to efficiently accelerate particles up to high energies. Although appealing from a global energetic point of view, this scenario of cosmic ray production is nowadays challenged by a number of arguments, including the difficulty to account for the cosmic rays of very high energies as well as the peculiarities of the cosmic ray spectrum measured near Earth. On the other hand, most of the massive stars which end their lives as supernovae are believed to be born within clusters formed inside dense molecular clouds. During their lives, the clustered stars collectively carve galactic-scale cavities, called superbubbles, in their parent environment. The stellar winds and subsequent supernova explosions deposit alarge amount of mechanical, thermal and turbulent energy within these superbubbles, which makes them appealing candidates as cosmic ray sources. However, the acceleration of particles in these environments has been scarcely considered. This thesis therefore aims at reviewing the relevant fundamental mechanisms of acceleration in superbubbles in order to provide an investigation by means of semi-analytical modelling derived fromfirst principles. Collective effects such as shock collisions and successive events of particle reacceleration are discussed. A self-consistent model accounting for the nonlinear feedback of the particles on the environment is described. The hydromagnetic turbulence, the multiple supernovae and the stellar winds are found to be efficient sources of cosmic rays. The spectrum of the accelerated particles is not only influenced by the collective effectsand the propagation in the bubble interior, but also by the magnetised supershell which surrounds the bubble and the intermittency of the mechanical power delivered by the stars. The overall contribution of galactic star clusters and superbubbles to the cosmic ray spectrum is eventually discussed, as well as recent gamma-ray observations.Il a Ă©tĂ© dĂ©couvert il y a plus dâun siĂšcle que le milieu interstellaire est rempli de particules chargĂ©es appelĂ©es rayons cosmiques. Ces particules sont des composantes de premier-plan dans lâĂ©cosystĂšme galactique. Non seulement elles influencent les propriĂ©tĂ©s des plasmas et des champs magnĂ©tiques, mais elles impactent Ă©galement la dynamique des gaz, rĂ©gissent lâĂ©volution des nuages molĂ©culaires et rĂ©gulent la formation des Ă©toiles.Cependant, la question de leurs sources reste sans rĂ©ponse dĂ©finitive. Les Ă©nergies gigantesques que certaines de ces particules atteignent lorsquâelles impactent lâatmosphĂšre terrestre suggĂšrent quâelles doivent ĂȘtre produites dans les systĂšmes astrophysiques les plus puissants de la galaxie, comme les Ă©toiles massives qui finissent par exploser en supernovae. Au cours des derniĂšres dĂ©cennies, il a Ă©tĂ© dĂ©montrĂ© que les vestiges de supernovae accĂ©lĂšrent en effet des particules. Bien que sĂ©duisant dâun point de vue Ă©nergĂ©tique, ce scĂ©nario de production de rayons cosmiques est aujourdâhui Ă©branlĂ© par un certain nombre dâarguments, incluant la difficultĂ© de rendre compte des rayons cosmiques de trĂšs hautes Ă©nergies ainsi que des particularitĂ©s du spectre mesurĂ© sur Terre. Dâun autre cĂŽtĂ©, la plupart des Ă©toiles massives qui explosent en supernovae Ă la fin de leur vie sont supposĂ©es naĂźtre au sein dâamas formĂ©s Ă lâintĂ©rieur de nuages molĂ©culaires denses. Durant leur vie, les Ă©toiles creusent autour des amas des cavitĂ©s qui atteignent des dimensions galactiques et que lâon appelle des superbulles. Les vents stellaires et les explosions de supernovae dĂ©posent une grande quantitĂ© dâĂ©nergie mĂ©canique, thermique et turbulente Ă lâintĂ©rieur de ces cavitĂ©s, ce qui en font des candidates de choix comme sources du rayonnement cosmique. Pourtant, lâaccĂ©lĂ©ration des particules dans ces environnements a Ă©tĂ© rarement considĂ©rĂ©e. Cette thĂšse a donc pour but de rĂ©capituler les mĂ©canismes dâaccĂ©lĂ©rations fondamentaux supposĂ©s agir Ă lâintĂ©rieur des superbulles, afin de produire des modĂšles semianalytiquesdĂ©rivĂ©s dâĂ©quations fondamentales. Des effets collectifs comme les collisions entre ondes de choc et les rĂ©accĂ©lĂ©rations successives des particules confinĂ©es sont discutĂ©s. Un modĂšle auto-consistant, prenant en compte la rĂ©ponse non-linĂ©aire des particules sur leur environnement, est dĂ©crit. Il est montrĂ© que la turbulence hydromagnĂ©tique, les multiples supernovae et les vents stellaires produisent efficacement des rayons cosmiques. Lespectre des particules accĂ©lĂ©rĂ©es est non seulement influencĂ© par les effets collectifs et la propagation dans lâintĂ©rieur de la bulle, mais aussi par la coquille magnĂ©tisĂ©e qui dĂ©limite la bulle et le caractĂšre intermittent de la puissance mĂ©canique dĂ©livrĂ©e par les Ă©toiles. La contribution globale des amas stellaires et des superbulles galactiques au spectre des rayons cosmiques est finalement discutĂ©e, ainsi que des observations rĂ©centes en rayonsgamma
Les superbulles et l'origine des rayons cosmiques
It has been known for more than a century that the interstellar medium is full of charged particles called cosmic rays. These particles are crucial agents in the galactic ecosystem. Not only do they influence the properties of space plasmas and magnetic fields, they also impact the gas dynamics, drive the evolution of molecular clouds and regulate the formation of the stars. Yet, there is still no definite answer to the question of their sources. Given the gigantic energies that some of these particles carry when they impact the Earth atmosphere, they are much likely produced in the most energetic astrophysical systems of the galaxy such as massive stars eventually exploding as supernovae. During the last decades, the supernova remnant shocks have indeed been proved to efficiently accelerate particles up to high energies. Although appealing from a global energetic point of view, this scenario of cosmic ray production is nowadays challenged by a number of arguments, including the difficulty to account for the cosmic rays of very high energies as well as the peculiarities of the cosmic ray spectrum measured on Earth. On the other hand, most of the massive stars which end their lives as supernovae are believed to be born within clusters formed inside dense molecular clouds. During their lives, the clustered stars collectively carve galactic-scale cavities, called superbubbles, in their parent environment. The stellar winds and subsequent supernova explosions deposit a large amount of mechanical, thermal and turbulent energy within these superbubbles, which makes them appealing candidates as cosmic ray sources. However, the acceleration of particles in these environments has been scarcely considered. This thesis therefore aims at reviewing the relevant fundamental mechanisms of acceleration in superbubbles in order to provide an investigation by means of semi-analytical modellings derived from first principles. Collective effects such as shock collisions and successive events of particle reacceleration are discussed. A self-consistent model accounting for the non-linear feedback of the particles on the environment is described. The hydromagnetic turbulence, the multiple supernovae and the stellar winds are found to be efficient sources of cosmic rays. The spectrum of the accelerated particles is not only influenced by the collective effects and the propagation in the bubble interior, but also by the magnetised supershell which surrounds the bubble and the intermittency of the mechanical power delivered by the stars. The overall contribution of galactic star clusters and superbubbles to the cosmic ray spectrum is eventually discussed, as well as recent gamma-ray observations.Il a Ă©tĂ© dĂ©couvert il y a plus d'un siĂšcle que le milieu interstellaire est rempli de particules chargĂ©es appelĂ©es rayons cosmiques. Ces particules sont des composantes de premier-plan dans l'Ă©cosystĂšme galactique. Non seulement elles influencent les propriĂ©tĂ©s des plasmas et des champs magnĂ©tiques, mais elles impactent Ă©galement la dynamique des gaz, rĂ©gissent l'Ă©volution des nuages molĂ©culaires et rĂ©gulent la formation des Ă©toiles. Cependant, la question de leurs sources reste sans rĂ©ponse dĂ©finitive. Les Ă©nergies gigantesques que certaines de ces particules atteignent lorsqu'elles impactent l'atmosphĂšre terrestre suggĂšrent qu'elles doivent ĂȘtre produites dans les systĂšmes astrophysiques les plus puissants de la galaxie, comme les Ă©toiles massives qui finissent par exploser en supernovae. Au cours des derniĂšres dĂ©cennies, il a Ă©tĂ© dĂ©montrĂ© que les vestiges de supernovae accĂ©lĂšrent en effet des particules. Bien que sĂ©duisant d'un point de vue Ă©nergĂ©tique, ce scĂ©nario de production de rayons cosmiques est aujourd'hui Ă©branlĂ© par un certain nombre d'arguments, incluant la difficultĂ© de rendre compte des rayons cosmiques de trĂšs hautes Ă©nergies ainsi que des particularitĂ©s du spectre mesurĂ© sur Terre. D'un autre cĂŽtĂ©, la plupart des Ă©toiles massives qui explosent en supernovae Ă la fin de leur vie sont supposĂ©es naĂźtre au sein d'amas formĂ©s Ă l'intĂ©rieur de nuages molĂ©culaires denses. Durant leur vie, les Ă©toiles creusent autour des amas des cavitĂ©s qui atteignent des dimensions galactiques et que l'on appelle des superbulles. Les vents stellaires et les explosions de supernovae dĂ©posent une grande quantitĂ© d'Ă©nergie mĂ©canique, thermique et turbulente Ă l'intĂ©rieur de ces cavitĂ©s, ce qui en font des candidates de choix comme sources du rayonnement cosmique. Pourtant, l'accĂ©lĂ©ration des particules dans ces environnements a Ă©tĂ© rarement considĂ©rĂ©e. Cette thĂšse a donc pour but de rĂ©capituler les mĂ©canismes d'accĂ©lĂ©rations fondamentaux supposĂ©s agir Ă l'intĂ©rieur des superbulles, afin de produire des modĂšles semi-analytiques dĂ©rivĂ©s d'Ă©quations fondamentales. Des effets collectifs comme les collisions entre ondes de choc et les rĂ©accĂ©lĂ©rations successives des particules confinĂ©es sont discutĂ©s. Un modĂšle auto-consistant, prenant en compte la rĂ©ponse non-linĂ©aire des particules sur leur environnement, est dĂ©crit. Il est montrĂ© que la turbulence hydromagnĂ©tique, les multiples supernovae et les vents stellaires produisent efficacement des rayons cosmiques. Le spectre des particules accĂ©lĂ©rĂ©es est non seulement influencĂ© par les effets collectifs et la propagation dans l'intĂ©rieur de la bulle, mais aussi par la coquille magnĂ©tisĂ©e qui dĂ©limite la bulle et le caractĂšre intermittent de la puissance mĂ©canique dĂ©livrĂ©e par les Ă©toiles. La contribution globale des amas stellaires et des superbulles galactiques au spectre des rayons cosmiques est finalement discutĂ©e, ainsi que des observations rĂ©centes en rayons gammas
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