A5020755506- Dark Matter and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Neutrino Physics Research
- Cosmology and Gravitation Theories
- Astrophysics and Cosmic Phenomena
- Particle Detector Development and Performance
- Galaxies: Formation, Evolution, Phenomena
- High-Energy Particle Collisions Research
- Black Holes and Theoretical Physics
- Radio Astronomy Observations and Technology
- Quantum Chromodynamics and Particle Interactions
- Astrophysical Phenomena and Observations
- Astronomy and Astrophysical Research
- Scientific Research and Discoveries
- Solar and Space Plasma Dynamics
- Gamma-ray bursts and supernovae
- Computational Physics and Python Applications
- Advanced X-ray Imaging Techniques
- Semantic Web and Ontologies
- Nonlinear Waves and Solitons
- Stellar, planetary, and galactic studies
- Algebraic structures and combinatorial models
- Pulsars and Gravitational Waves Research
- Advanced Text Analysis Techniques
- Fractal and DNA sequence analysis
University of Copenhagen
2017-2024
Carleton University
2023
École Polytechnique Fédérale de Lausanne
2007-2017
European Organization for Nuclear Research
2011-2015
Bogolyubov Institute for Theoretical Physics
2010
École Polytechnique
2010
Centre National de la Recherche Scientifique
2010
Institut de Recherche sur les Phénomènes Hors Équilibre
2009
Institut des Hautes Études Scientifiques
2004-2008
University of Chicago
2001-2003
We report a weak line at 3.52±0.02 keV in x-ray spectra of the Andromeda galaxy and Perseus cluster observed by metal-oxide-silicon (MOS) p-n (PN) CCD cameras XMM-Newton telescope. This is not known as an atomic galaxies or clusters. It becomes stronger towards centers objects; for than M31; absent spectrum deep "blank sky" data set. Although each object it hard to exclude that feature due instrumental effect line, consistent with behavior dark matter decay line. Future (non-)detections this...
We present a comprehensive overview of an extension the Standard Model that contains three right-handed (sterile) neutrinos with masses below electroweak scale [the Neutrino Minimal Model, (nuMSM)]. consider history Universe from inflationary era through today and demonstrate most observed phenomena beyond can be explained within framework this model. review mechanism baryon asymmetry in nuMSM discuss dark matter candidate warm or cold satisfies all existing constraints. From viewpoint...
This paper describes the physics case for a new fixed target facility at CERN SPS. The SHiP (Search Hidden Particles) experiment is intended to hunt in largely unexplored domain of very weakly interacting particles with masses below Fermi scale, inaccessible LHC experiments, and study tau neutrino physics. same proton beam setup can be used later look decays tau-leptons lepton flavour number non-conservation, $\tau\to 3\mu$ search weakly-interacting sub-GeV dark matter candidates. We discuss...
High resolution N-body simulations of galactic cold dark matter haloes indicate that we should expect to find a few satellite galaxies around the Milky Way whose have maximum circular velocity in excess 40 kms. Yet, with exception Magellanic Clouds and Sagittarius dwarf, which likely reside subhaloes significantly larger velocities than this, bright satellites all appear below As recently highlighted by Boylan-Kolchin et al., this discrepancy implies majority most massive within halo are...
A new general purpose fixed target facility is proposed at the CERN SPS accelerator which aimed exploring domain of hidden particles and make measurements with tau neutrinos. Hidden are predicted by a large number models beyond Standard Model. The high intensity 400~GeV beam allows probing wide variety containing light long-lived exotic masses below ${\cal O}$(10)~GeV/c$^2$, including very weakly interacting low-energy SUSY states. experimental programme capable being extended in future,...
Abstract With the establishment and maturation of experimental programs searching for new physics with sizeable couplings at LHC, there is an increasing interest in broader particle astrophysics community exploring light feebly-interacting particles as a paradigm complementary to New Physics sector TeV scale beyond. FIPs 2020 has been first workshop fully dedicated was held virtually from 31 August 4 September 2020. The gathered together experts collider, beam dump, fixed target experiments,...
Abstract The existence of nonzero neutrino masses points to the likely multiple Standard Model neutral fermions. When such states are heavy enough that they cannot be produced in oscillations, referred as leptons (HNLs). In this white paper, we discuss present experimental status HNLs including colliders, beta decay, accelerators, well astrophysical and cosmological impacts. We importance continuing search for HNLs, its potential impact on our understanding key fundamental questions,...
We revisit Lyman-α bounds on the dark matter mass in Λ Warm Dark Matter (ΛWDM) models, and derive new case of mixed Cold plus models (ΛCWDM), using a set up which is good approximation for several theoretically well-motivated models. combine WMAP5 results with two different data sets, including observations from Sloan Digital Sky Survey. pay special attention to systematics, test various possible sources error, compare statistical approaches. Expressed terms non-resonantly produced sterile...
We discuss the bounds on mass of Dark Matter (DM) particles, coming from analysis DM phase-space distribution in dwarf spheroidal galaxies (dSphs). After reviewing existing approaches, we choose two methods to derive such a bound. The first one depends information about current phase space particles only, while second uses both initial and final distributions. recent data dSphs as well astronomical uncertainties relevant parameters. As an application, present lower various dSphs, using...
We show that the evolution of magnetic fields in a primordial plasma, filled with Standard Model particles, at temperatures T > 10 MeV is strongly affected by quantum chiral anomaly -- an effect has been neglected previously. Although reactions equilibrating left and right-chiral electrons are deep thermal equilibrium for < 80 TeV, asymmetry between these particle develops presence strong fields. This results helicity transfer from shorter to longer scales. also leads effective generation...
Sterile neutrinos with masses in the keV range are viable candidates for warm dark matter. We analyze existing data extragalactic diffuse X-ray background signatures of sterile neutrino decay. The absence detectable signal within current uncertainties measurements puts model-independent constraints on allowed values mass and mixing angle, which we present this work.
In the recent paper of Hooper and Goodenough (2010) [10] it was reported that γ-ray emission from Galactic Center region contains an excess compared to contributions large-scale diffuse known point sources. This argued be consistent with a signal annihilation Dark Matter power law density profile. We reanalyze Fermi data find instead is "standard model" The main reason for discrepancy interpretation different (as previous works) spectrum source at assumed by [10]. discuss possible reasons...
We propose a strategy for how to look dark matter particles possessing radiative decay channel and derive constraints on their parameters from observations of x rays our own Galaxy its dwarf satellites. When applied sterile neutrinos in the keV mass range this approach gives significant improvement restrictions neutrino compared with previous works.
Previous fits of sterile neutrino dark matter (DM) models to cosmological data ruled out masses smaller than approximately 8 keV, assuming a production mechanism that is not the best motivated from particle physics point view. Here we focus on realistic extension standard model with three neutrinos, consistent oscillation and baryogenesis, lightest being DM particle. We show for each mass >or= 2 keV there exists at least one accounting 100% Lyman-alpha other cosmological, astrophysical, data.
We detect a line at 3.539±0.011 keV in the deep exposure data set of Galactic center region, observed with x-ray multi-mirror mission Newton. The dark matter interpretation signal Perseus galaxy cluster, Andromeda [A. Boyarsky et al., Phys. Rev. Lett. 113, 251301 (2014)], and stacked spectra clusters [E. Bulbul Astrophys. J. 789, 13 together nonobservation blank-sky data, put both lower upper limits on possible intensity data. Our result is consistent these constraints for class Milky Way...
We use BOSS DR9 quasars to constrain 2 cases of dark matter models: cold-plus-warm (C+WDM) where the warm component is a thermal relic, and sterile neutrinos resonantly produced in presence lepton asymmetry (RPSN). establish constraints on relic mass m_x its relative abundance $F=\Omega_{wdm}/\Omega_{dm}$ using suite hydrodynamical simulations 28 C+WDM configurations. find that 3 sigma bounds approximately follow F ~ $0.35 (keV/m_x)^{-1.37}$ from alone. also neutrino mixing angle by...
We analyze the influence of decaying sterile neutrinos with masses in range 1-140 MeV on primordial Helium-4 abundance, explicitly solving Boltzmann equations for all particle species, taking into account neutrino flavour oscillations, and paying special attention to systematic uncertainties. show that Helium abundance depends only lifetime not way active-sterile mixing is distributed between flavours, derive an upper bound lifetime. also demonstrate recent results Izotov & Thuan...
We study the dynamics of a plasma charged relativistic fermions at very high temperature $T\gg m$, where $m$ is fermion mass, coupled to electromagnetic field. In particular, we derive magneto-hydrodynamical description evolution such plasma. show that, as compared conventional MHD for non-relativistic particles, hydrodynamical involves new degrees freedom described by pseudo-scalar field originating in local asymmetry densities left-handed and right-handed fermions. This can be interpreted...
A bstract We review and revise phenomenology of the GeV-scale heavy neutral leptons (HNLs). extend previous analyses by including more channels HNLs production decay provide with refined treatment, QCD corrections for masses $$ \mathcal{O} <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>O</mml:mi> </mml:math> (1) GeV. summarize relevance individual different masses, resolving a few discrepancies in literature. Our final results are directly suitable sensitivity studies...
We re-analyse high redshift and resolution Lyman-$α$ forest spectra considered in (Viel et al 2013), seeking to constrain the properties of warm dark matter particles. Compared this previous work, we consider a wider range thermal histories intergalactic medium. find that both cold models can explain cut-off observed flux power high-resolution observations equally well. This implies, however, very different underlying re-ionisation models. discuss how remove degeneracy.
We present results of a search for the 3.5 keV emission line in our recent very long (∼ 1.4 Ms) XMM–Newton observation Draco dwarf spheroidal galaxy. The astrophysical X-ray from such dark matter-dominated galaxies is faint, thus they provide test matter origin previously detected other massive, but bright objects, as and galaxy clusters. do not detect statistically significant Draco; this constrains lifetime decaying particle to τ > (7–9) × 1027 s at 95 per cent CL (combining all three...
We constrain the lifetime of thermally produced Heavy Neutral Leptons (HNLs) from primordial nucleosynthesis. show that even a small fraction mesons present in plasma leads to over-production helium. This puts an upper bound on HNLs $\tau_{N}<0.02$ s for masses $m_{N}>m_{\pi}$ (as compared 0.1 reported previously). In combination with accelerator searches, this allows us put new lower and defining "bottom line" HNL searches at future Intensity Frontier experiments.
The flux power spectrum of the high resolution Lyman-$\alpha$ forest data exhibits suppression at small scales. origin this can be due to long-sought warm dark matter (WDM) or thermal effects, related largely unknown reionization history Universe. Previous works explored a specific class histories that exhibit sufficiently strong supression and leave little room for interpretation. In work we choose different histories, fully compatible with available on evolution reionization, but much...
Aims.We improve the earlier restrictions on parameters of warm dark matter (DM) in form a sterile neutrinos.