Aurélien Barrau
A5060569883- Cosmology and Gravitation Theories
- Black Holes and Theoretical Physics
- Noncommutative and Quantum Gravity Theories
- Dark Matter and Cosmic Phenomena
- Astrophysics and Cosmic Phenomena
- Particle Detector Development and Performance
- Pulsars and Gravitational Waves Research
- Radiation Detection and Scintillator Technologies
- Relativity and Gravitational Theory
- Solar and Space Plasma Dynamics
- Atomic and Subatomic Physics Research
- Quantum Electrodynamics and Casimir Effect
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Particle physics theoretical and experimental studies
- French Urban and Social Studies
- Quantum Mechanics and Applications
- Geophysics and Gravity Measurements
- Astro and Planetary Science
- Adaptive optics and wavefront sensing
- Nuclear Physics and Applications
- Ionosphere and magnetosphere dynamics
- Atmospheric Ozone and Climate
Laboratoire de Physique Subatomique et de Cosmologie
2016-2025
Institut National de Physique Nucléaire et de Physique des Particules
2015-2025
Centre National de la Recherche Scientifique
2015-2025
Université Grenoble Alpes
2016-2025
Sorbonne Université
1997-2021
Laboratoire de Physique Nucléaire et de Hautes Énergies
1997-2021
Université Paris Cité
1997-2021
Institut polytechnique de Grenoble
2013-2019
Université Joseph Fourier
2006-2018
European Organization for Nuclear Research
2012-2016
A precision measurement by the Alpha Magnetic Spectrometer on International Space Station of positron fraction in primary cosmic rays energy range from 0.5 to 350 GeV based $6.8\ifmmode\times\else\texttimes\fi{}{10}^{6}$ and electron events is presented. The very accurate data show that steadily increasing 10 $\ensuremath{\sim}250\text{ }\text{ }\mathrm{GeV}$, but, 20 250 GeV, slope decreases an order magnitude. spectrum shows no fine structure, ratio observable anisotropy. Together, these...
A precise measurement of the proton flux in primary cosmic rays with rigidity (momentum/charge) from 1 GV to 1.8 TV is presented based on 300 million events. Knowledge dependence important understanding origin, acceleration, and propagation rays. We present detailed variation spectral index for first time. The progressively hardens at high rigidities.Received 6 March 2015DOI:https://doi.org/10.1103/PhysRevLett.114.171103This article available under terms Creative Commons Attribution 3.0...
Measurements of the positron fraction in high energy cosmic rays using space-borne Alpha Magnetic Spectrometer have been extended to energies 500 GeV. The new results show that stops increasing with at around 200
Precision measurements by the Alpha Magnetic Spectrometer on International Space Station of primary cosmic-ray electron flux in range 0.5 to 700 GeV and positron 500 are presented. The each require a description beyond single power-law spectrum. Both change their behavior at ∼30 but fluxes significantly different magnitude energy dependence. Between 20 200 spectral index is harder than index. determination differing indices versus new observation provides important information origins...
Knowledge of the precise rigidity dependence helium flux is important in understanding origin, acceleration, and propagation cosmic rays. A measurement primary rays with (momentum/charge) from 1.9 GV to 3 TV based on 50 million events presented compared proton flux. The detailed variation spectral index for first time. progressively hardens at rigidities larger than 100 GV. similar that though magnitudes are different. Remarkably, ratio increases up 45 then becomes constant; above well...
A precision measurement by AMS of the antiproton flux and antiproton-to-proton ratio in primary cosmic rays absolute rigidity range from 1 to 450 GV is presented based on 3.49×10^{5} events 2.42×10^{9} proton events. The fluxes ratios charged elementary particles are also presented. In ∼60 ∼500 GV, p[over ¯], p, positron e^{+} found have nearly identical dependence electron e^{-} exhibits a different dependence. Below 60 (p[over ¯]/p), ¯]/e^{+}), (p/e^{+}) each reaches maximum. From show no...
Knowledge of the rigidity dependence boron to carbon flux ratio (B/C) is important in understanding propagation cosmic rays. The precise measurement B/C from 1.9 GV 2.6 TV, based on 2.3 million and 8.3 nuclei collected by AMS during first 5 years operation, presented. detailed variation with spectral index reported for time. does not show any significant structures contrast many ray models that require such at high rigidities. Remarkably, above 65 GV, well described a single power law R^{Δ}...
We report the observation of new properties primary cosmic rays He, C, and O measured in rigidity (momentum/charge) range 2 GV to 3 TV with 90×10^{6} helium, 8.4×10^{6} carbon, 7.0×10^{6} oxygen nuclei collected by Alpha Magnetic Spectrometer (AMS) during first five years operation. Above 60 GV, these three spectra have identical dependence. They all deviate from a single power law above 200 harden an way.
We present a measurement of the cosmic ray (e^{+}+e^{-}) flux in range 0.5 GeV to 1 TeV based on analysis 10.6 million events collected by AMS. The statistics and resolution AMS provide precision flux. is smooth reveals new distinct information. Above 30.2 GeV, can be described single power law with spectral index γ=-3.170±0.008(stat+syst)±0.008(energy scale).
Precision measurements of cosmic ray positrons are presented up to 1 TeV based on 1.9 million collected by the Alpha Magnetic Spectrometer International Space Station. The positron flux exhibits complex energy dependence. Its distinctive properties (a) a significant excess starting from 25.2±1.8 GeV compared lower-energy, power-law trend, (b) sharp dropoff above 284+91−64 GeV, (c) in entire range is well described sum term associated with produced collision rays, which dominates at low...
We report on the observation of new properties secondary cosmic rays Li, Be, and B measured in rigidity (momentum per unit charge) range 1.9 GV to 3.3 TV with a total 5.4×10^{6} nuclei collected by AMS during first five years operation aboard International Space Station. The Li fluxes have an identical dependence above 7 all three 30 Li/Be flux ratio 2.0±0.1. deviate from single power law 200 way. This behavior has also been observed measurement primary He, C, O but dependences are...
Primary cosmic-ray elemental spectra have been measured with the balloon-borne Cosmic Ray Energetics And Mass (CREAM) experiment since 2004. The third CREAM payload (CREAM-III) flew for 29 days during 2007-2008 Antarctic season. Energies of incident particles above 1 TeV are a calorimeter. Individual elements clearly separated charge resolution ~0.12 e (in units) and ~0.14 protons helium nuclei, respectively, using two layers silicon detectors. proton energy at top atmosphere harder than...
Precision results on cosmic-ray electrons are presented in the energy range from 0.5 GeV to 1.4 TeV based $28.1\ifmmode\times\else\texttimes\fi{}{10}^{6}$ collected by Alpha Magnetic Spectrometer International Space Station. In entire electron and positron spectra have distinctly different magnitudes dependences. The flux exhibits a significant excess starting $42.{1}_{\ensuremath{-}5.2}^{+5.4}\text{ }\text{ }\mathrm{GeV}$ compared lower trends, but nature of this is above...
Cosmic ray antiprotons provide an important probe for the study of galactic Dark Matter, as they could be produced by exotic sources. On other hand, are anyway standard nuclear reactions cosmic nuclei on interstellar matter. This process is responsible a background flux that must carefully determined to estimate detectability hypothetical signal. Estimates this suffer from potential uncertainties various origins. The propagation depends several physical characteristics Galaxy which poorly...
Holonomy corrections to scalar perturbations are investigated in the loop quantum cosmology framework. Due effective approach, modifications of algebra constraints generically lead anomalies. In order remove those anomalies, counter terms introduced. We find a way explicitly fulfill conditions for anomaly freedom and we give explicit expressions terms. Surprisingly, -scheme naturally arises this procedure. The gauge-invariant variables found equations motion anomaly-free derived. Finally,...
We present the precision measurement from May 2011 to 2017 (79 Bartels rotations) of proton fluxes at rigidities 1 60 GV and helium 1.9 based on a total 1×10^{9} events collected with Alpha Magnetic Spectrometer aboard International Space Station. This is in solar cycle 24, which has maximum April 2014. observed that, below 40 GV, flux show nearly identical fine structures both time relative amplitude. The amplitudes decrease increasing rigidity vanish above GV. are reduced during period,...
Loop quantum cosmology yields two kinds of corrections to the effective equations motion for cosmological perturbations. Here we focus on holonomy kind and study problem closure resulting algebra constraints when a scalar field is considered in matter Hamiltonian. Up now, tensor, vector perturbations were studied independently, leading different algebras constraints. The structures related imposed by requirement anomaly freedom. In this article show that can be modified very simple...
Quantum gravity effects could make a black hole explode in time shorter than the Hawking radiation time, via local tunneling through white solution. Here we estimate size of primordial exploding today this process, using simple generic model. Fast radio bursts, strong signals with millisecond duration, which are probably extragalactic origin and have an unknown source, wavelengths not far from expected hole. We also discuss high-energy component signal. These results suggest new window for...
The Planck collaboration has provided us rich information about the early universe, and a host of new observational missions will soon shed further light on `anomalies' that appear to exist largest angular scales. From quantum gravity perspective, it is natural inquire if one can trace back origin such puzzling features scale physics. Loop cosmology provides promising avenue explore this issue because its resolution big bang singularity. Thanks advances over last decade, theory matured...
This article lays out a complete framework for an effective theory of cosmological perturbations with corrections from canonical quantum gravity. Since several examples exist quantum-gravity effects that change the structure space-time, classical perturbative treatment must be rethought carefully. The present discussion provides unified picture previous works, together new treatments higher-order and specification initial states.
We present high-statistics, precision measurements of the detailed time and energy dependence primary cosmic-ray electron flux positron over 79 Bartels rotations from May 2011 to 2017 in range 1 50 GeV. For first time, charge-sign dependent modulation during solar maximum has been investigated detail by leptons alone. Based on 23.5×10^{6} events, we report observation short-term structures timescale months coincident both flux. These are not visible e^{+}/e^{-} ratio. The across polarity...
A precision measurement of the nitrogen flux with rigidity (momentum per unit charge) from 2.2 GV to 3.3 TV based on 2.2×10^{6} events is presented. The detailed dependence spectral index presented for first time. rapidly hardens at high rigidities and becomes identical indices primary He, C, O cosmic rays above ∼700 GV. We observed that Φ_{N} can be as sum its component Φ_{N}^{P} secondary Φ_{N}^{S}, Φ_{N}=Φ_{N}^{P}+Φ_{N}^{S}, we found well described by weighted oxygen Φ_{O} (primary rays)...
Quantum gravity is sometimes considered as a kind of metaphysical speculation.In this review, we show that, although still extremely difficult to reach, observational signatures can in fact be expected.The early universe an invaluable laboratory probe "Planck scale physics".Focusing on Loop Gravity one the best candidate for non-perturbative and background-independant quantization gravity, detail some expected features.Invited topical review Classical Gravity.
Loop quantum cosmology provides an efficient framework to study the evolution of Universe beyond classical Big Bang paradigm. Because holonomy corrections, singularity is replaced by a "bounce". The dynamics background investigated into details, as function parameters model. In particular, conditions required for inflation occur are carefully considered and shown be generically met. propagation gravitational waves then in this framework. By both numerical analytical approaches, primordial...
It is possible that black holes hide a core of Planckian density, sustained by quantum-gravitational pressure. As hole evaporates, the remembers initial mass and final explosion occurs at macroscopic scale. We investigate phenomenological consequences this idea. Under several rough assumptions, we estimate up to short gamma-ray bursts per day, around 10 MeV, with isotropic distribution, can be expected coming from region few hundred light years us.