A5088115357- Dark Matter and Cosmic Phenomena
- Astrophysics and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Cosmology and Gravitation Theories
- Neutrino Physics Research
- Particle Detector Development and Performance
- Galaxies: Formation, Evolution, Phenomena
- Gamma-ray bursts and supernovae
- Atomic and Subatomic Physics Research
- Radio Astronomy Observations and Technology
- Pulsars and Gravitational Waves Research
- Solar and Space Plasma Dynamics
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Black Holes and Theoretical Physics
- Nuclear physics research studies
- Scientific Research and Discoveries
- Particle Accelerators and Free-Electron Lasers
- Radioactive Decay and Measurement Techniques
- Atmospheric Ozone and Climate
- High-Energy Particle Collisions Research
- Geophysics and Gravity Measurements
- Nuclear Physics and Applications
- Energetic Materials and Combustion
- Radiation Detection and Scintillator Technologies
Laboratoire d'Annecy-le-Vieux de Physique Théorique
2016-2025
Centre National de la Recherche Scientifique
2015-2024
Université Savoie Mont Blanc
2012-2022
Université Grenoble Alpes
2018-2022
Pontifical Catholic University of Rio de Janeiro
2021
Université Libre de Bruxelles
2019
RWTH Aachen University
2016-2017
Laboratoire d’Annecy de Physique des Particules
2014-2015
Laboratoire de Physique Théorique
2015
Institut National de Physique Nucléaire et de Physique des Particules
2014
Recent results from the PAMELA satellite indicate presence of a large flux positrons (relative to electrons) in cosmic ray spectrum between approximately 10 and 100 GeV. As annihilating dark matter particles many models are predicted contribute positron this energy range, great deal interest has resulted observation. Here, we consider pulsars (rapidly spinning, magnetized neutron stars) as an alternative source signal. After calculating contribution electron spectra pulsars, find that...
We have searched for solar axions or similar particles that couple to two photons by using the CERN Axion Solar Telescope (CAST) setup with improved conditions in all detectors. From absence of excess X-rays when magnet was pointing Sun, we set an upper limit on axion-photon coupling 8.8 x 10^{-11} GeV^{-1} at 95% CL m_a <~ 0.02 eV. This result is best experimental over a broad range axion masses and eV also supersedes previous derived from energy-loss arguments globular-cluster stars.
We show that the complex shape of cosmic ray (CR) spectrum, as recently measured by PAMELA and inferred from Fermi-LAT γ-ray observations molecular clouds in Gould belt, can be naturally understood terms basic plasma astrophysics phenomena. A break a harder to softer spectrum at rigidity R is approximately equal 10 GV follows transition transport dominated advection particles with Alfvén waves regime where diffusion turbulence generated same CRs dominant. second 200 happens when diffusive...
Stellar-mass Primordial Black Holes (PBH) have been recently reconsidered as a Dark Matter (DM) candidate, after the aLIGO discovery of several binary BH mergers with masses tens $M_\odot$. accretion on such massive objects leads to emission high-energy photons, capable altering ionization and thermal history universe. This in turn affects statistical properties cosmic microwave background (CMB) anisotropies. Previous analyses assumed spherical accretion. We argue that this approximation...
Even if massive ($10\,M_\odot \lesssim M 10^4 M_\odot$) primordial black holes (PBHs) can only account for a small fraction of the dark matter (DM) in universe, they may still be responsible sizable coalescence events measured by LIGO/Virgo, and/or act as progenitors supermassive (SMBHs) observed already at high redshift ($z\gtrsim 6$). In presence dominant, non-PBH DM component, bounds set CMB via an altered ionization history are modified. We revisit cosmological accretion halo around PBHs...
We consider a cosmological model in which fraction fdcdm of the Dark Matter (DM) is allowed to decay an invisible relativistic component, and compute resulting constraints on both width (or inverse lifetime) Γdcdm from purely gravitational arguments. report full derivation Boltzmann hierarchy, correcting mistake previous literature, impact decay—as function lifetime—on CMB matter power spectra. From only, we obtain that no more than 3.8% DM could have decayed time between recombination today...
Using the updated proton and helium fluxes just released by AMS-02 experiment we reevaluate secondary astrophysical antiproton to ratio its uncertainties, compare it with preliminarly reported AMS-02. We find no unambiguous evidence for a significant excess respect expectations. Yet, some preference flatter energy dependence of diffusion coefficient (with MED benchmark often used in literature) starts emerge. Also, provide first assessment room left exotic components such as Galactic Dark...
Sterile neutrinos with masses up to <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi mathvariant="script">O</a:mi><a:mo stretchy="false">(</a:mo><a:mn>100</a:mn><a:mo stretchy="false">)</a:mo><a:mtext> </a:mtext><a:mtext> </a:mtext><a:mi>MeV</a:mi></a:math> can be copiously produced in a supernova (SN) core through the mixing active neutrinos. In this regard, SN 1987A detection of neutrino events has been used put constraints on active-sterile mixing, exploiting...
Hypothetical axionlike particles with a two-photon interaction would be produced in the sun by Primakoff process. In laboratory magnetic field ("axion helioscope"), they transformed into x-rays energies of few keV. Using decommissioned Large Hadron Collider test magnet, CERN Axion Solar Telescope ran for about 6 months during 2003. The first results from analysis these data are presented here. No signal above background was observed, implying an upper limit to axion-photon coupling...
We have searched for solar axions or other pseudoscalar particles that couple to two photons by using the CERN Axion Solar Telescope (CAST) setup. Whereas we previously reported results from CAST with evacuated magnet bores (Phase I), setting limits on lower mass axions, here report where were filled 4He gas II) of variable pressure. The introduction generates a refractive photon mγ, thereby achieving maximum possible conversion rate those axion masses ma match mγ. With 160 different...
Recent observations by IceCube, notably two PeV cascades accompanied events at energies ∼ (30–400) TeV, are clearly in excess over atmospheric background fluxes and beg for an astroparticle physics explanation. Although some models of astrophysical accelerators can account the within current statistics, intriguing features energy possibly angular distributions make worth exploring alternatives. Here, we entertain possibility interpreting data with a few mass scale decaying dark matter,...
Very high energy gamma rays are expected to be absorbed by the extragalactic background light over cosmological distances via process of electron-positron pair production. Recent observations cosmologically distant gamma-ray emitters ground based telescopes have, however, revealed a surprising degree transparency universe very photons. One possible mechanism explain this observation is oscillation between photons and axionlike particles (ALPs). Here we explore possibility further, focusing...
For neutrinos streaming from a supernova core, dense matter suppresses self-induced flavor transformations if the electron density ${n}_{e}$ significantly exceeds neutrino ${n}_{\ensuremath{\nu}}$ in conversion region. If is comparable to ${n}_{\ensuremath{\nu}}$, one finds multiangle decoherence, whereas standard transformation behavior requires that region safely above ${n}_{e}$. This condition need not be satisfied early phase after core bounce. Our new effect subtle consequence of...
Several groups have recently claimed evidence for an unaccounted gamma-ray excess over {the} diffuse backgrounds at few GeV in Fermi-LAT data a region around the Galactic Center, consistent with dark matter annihilation origin. We demonstrate that main spectral and angular features of this can be reproduced if they are mostly due to inverse Compton emission from high-energy electrons injected burst event ~10^52 - 10^53erg roughly O(10^6) years ago. consider example as proof principle...
A recently proposed model explains the rise in energy of positron fraction measured by PAMELA satellite terms hadronic production positrons aged supernova remnants, and acceleration therein. Here we present a preliminary calculation antiproton flux produced same mechanism. While is consistent with data, to proton ratio predicted at high energy, which strikingly distinguishes this scenario from other astrophysical explanations (such as pulsars). We briefly discuss important implications for...
Dark Matter is essential for structure formation in the late Universe so it must be stable on cosmological time scales. But how exactly? Only assuming decays into relativistic particles, we report an otherwise model independent bound lifetime of using current data. Since these affect only low ℓ multipoles CMB, expected to correlate with tensor-to-scalar ratio r as well curvature Ωk. We consider two models, including and r+Ωk respectively, versus data from Planck, WMAP, WiggleZ Baryon...
We derive new bounds on decaying Dark Matter from the gamma ray measurements of (i) isotropic residual (extragalactic) background by Fermi and (ii) Fornax galaxy cluster HESS. find that those are among most stringent constraints currently available, for a large range DM masses variety decay modes, excluding half-lives up to ~10^26 few 10^27 seconds. In particular, they rule out interpretation in terms e^\pm spectral features Pamela, HESS, unless very conservative choices adopted. also...
If the electroweak sector of standard model is described by classically conformal dynamics, early Universe evolution can be substantially altered. It already known that-contrarily to case-a first-order phase transition may occur. Here we show that, depending on parameters, a dramatically different scenario happen: A first-order, six massless quark QCD occurs first, which then triggers symmetry breaking. We derive necessary conditions for this dynamics occur, using specific example B-L model....
Using the updated proton and helium fluxes just released by AMS-02 experiment we reevaluate secondary astrophysical antiproton to ratio its uncertainties, compare it with preliminarly reported AMS-02. We find no unambiguous evidence for a significant excess respect expectations. Yet, some preference flatter energy dependence of diffusion coefficient (with MED benchmark often used in literature) starts emerge. Also, provide first assessment room left exotic components such as Galactic Dark...