A5007044846- Cosmology and Gravitation Theories
- Dark Matter and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Astrophysics and Cosmic Phenomena
- Neutrino Physics Research
- Galaxies: Formation, Evolution, Phenomena
- State Capitalism and Financial Governance
- Radio Astronomy Observations and Technology
- Global Financial Crisis and Policies
- Astronomy and Astrophysical Research
- Black Holes and Theoretical Physics
- Global Financial Regulation and Crises
- Scientific Research and Discoveries
- Stochastic processes and financial applications
- Law, logistics, and international trade
- Particle Detector Development and Performance
- Stellar, planetary, and galactic studies
- Turtle Biology and Conservation
- Quantum Information and Cryptography
- Geophysics and Gravity Measurements
- Advanced Differential Geometry Research
- High-Energy Particle Collisions Research
- Quantum Mechanics and Non-Hermitian Physics
- International Development and Aid
- Pulsars and Gravitational Waves Research
UNSW Sydney
2014-2024
The University of Melbourne
1998-2024
University of Illinois Urbana-Champaign
2023-2024
National Environment Agency
2022
RWTH Aachen University
2009-2014
European Organization for Nuclear Research
2008-2010
Max Planck Institute for Physics
2006-2009
Aarhus University
2009
Max Planck Society
2006-2008
Deutsches Elektronen-Synchrotron DESY
2004-2006
We present in this work a new calculation of the standard-model benchmark value for effective number neutrinos, $N_{\rm eff}^{\rm SM}$, that quantifies cosmological neutrino-to-photon energy densities. The takes into account neutrino flavour oscillations, finite-temperature effects quantum electrodynamics plasma to ${\cal O}(e^3)$, where $e$ is elementary electric charge, and full evaluation neutrino--neutrino collision integral. provide furthermore detailed assessment uncertainties SM}$...
We compute the dominant QED correction to neutrino-electron interaction rate in vicinity of neutrino decoupling early universe, and estimate its impact on effective number species $N_{\rm eff}$ cosmic microwave background anisotropy observations. find that is at sub-percent level, consistent with a recent by Jackson Laine. Relative work we include electron mass our computations, but restrict analysis enhanced $t$-channel contributions. The fractional change eff}^{\rm SM}$ due order $10^{-5}$...
Neutrino-neutrino interactions can lead to collective flavor conversion effects in supernovae and the early universe. We demonstrate that case of bipolar oscillations, where a dense gas neutrinos antineutrinos equal numbers completely converts from one another even if mixing angle is small, equivalent pendulum space. Bipolar corresponds swinging pendulum, which begins an unstable upright position (the initial flavor), passes through momentarily vertically downward other flavor) course its...
Precision cosmology and big-bang nucleosynthesis mildly favor extra radiation in the Universe beyond photons ordinary neutrinos, lending support to existence of low-mass sterile neutrinos. We use WMAP 7-year data, small-scale cosmic microwave background observations from ACBAR, BICEP, QuAD, SDSS 7th data release, measurement Hubble parameter HST derive credible regions for assumed common mass scale m{s} effective number N{s} thermally excited neutrino states. Our results are compatible with...
The Fisher matrix formalism has in recent times become the standard method for predicting precision with which various cosmological parameters can be extracted from future data. This approach is fast and generally returns accurate estimates parameter errors when individual likelihoods approximate a Gaussian distribution. However, where Gaussianity not respected (due, instance, to strong degeneracies), loses its reliability. In this paper, we compare results of those Monte Carlo simulations....
We study the gravitational clustering of big bang relic neutrinos onto existing cold dark matter (CDM) and baryonic structures within flat ΛCDM model, using both numerical simulations a semi-analytical linear technique, with aim understanding neutrinos' properties for direct detection purposes. In comparative analysis, we find that technique systematically underestimates amount wide range CDM halo neutrino masses. This invalidates earlier claims technique's applicability. then compute...
A recent numerical study by A. D. Dolgov, S. H. Hansen, Pastor, T. Petcov, G. Raffelt, and V. Semikoz (DHPPRS) [hep-ph/0201287] found that complete or partial equilibrium between all active neutrino flavours can be achieved before the big bang nucleosynthesis epoch via flavour oscillations, if oscillation parameters are those inferred from atmospheric solar data, and, in some cases, $\theta_{13}$ is also sizeable. As such, cosmological constraints on electron neutrino-antineutrino asymmetry...
We study cosmological models that contain sterile neutrinos with eV-range masses as suggested by reactor and short-baseline oscillation data. confront these both precision data (probing the CMB decoupling epoch) light-element abundances BBN epoch). In minimal ΛCDM model, such are strongly disfavoured current because they contribute too much hot dark matter. However, if framework is extended to include also additional relativistic degrees of freedom beyond three standard putative neutrinos,...
I give an overview of the effects neutrino masses in cosmology, focusing on role they play evolution cosmological perturbations. discuss how recent observations cosmic microwave background anisotropies and large-scale matter distribution can probe with greater precision than current laboratory experiments. describe several new techniques that will be used to cosmology future, as well advances computation nonlinear matter-power spectrum related observables.
Abstract We revisit the topic of invisible neutrino decay in precision cosmological context, via a first-principles approach to understanding cosmic microwave background and large-scale structure phenomenology such non-standard physics scenario. Assuming an effective Lagrangian which heavier standard-model ν H couples lighter one l massless scalar particle ϕ Yukawa interaction, we derive from first principles complete set Boltzmann equations, at both spatially homogeneous first-order...
Axions and axionlike particles (ALPs) are some of the most popular candidates for dark matter, with several viable production scenarios that make different predictions. In scenario in which axion is born after inflation, its field develops significant inhomogeneity evolves a highly nonlinear fashion. Understanding eventual abundance distribution axionic matter this therefore requires dedicated numerical simulations. So far community has focused efforts on simulations QCD axion, model...
In the scenario in which QCD axion dark matter is produced after inflation, Universe populated by large inhomogeneities on very small scales. Eventually, these fluctuations will collapse gravitationally to form dense miniclusters that trap up $\ensuremath{\sim}75%$ of within asteroid-mass clumps. Axion are physically tiny however, so haloscope experiments searching for axions directly Earth much more likely be probing ``minivoids''---the space between miniclusters. This seems like it ought...
Abstract Observational cosmology is rapidly closing in on a measurement of the sum M ν neutrino masses, at least simplest cosmologies, while opening door to probes non-standard hot dark matter (HDM) models. By extending method effective distributions, we show that any collection HDM species, with arbitrary temperatures, and distribution functions, including massive neutrinos, may be represented as single species. Implementing this FlowsForTheMasses non-linear perturbation theory for...
Surveys of weak gravitational lensing distant galaxies will be one the key cosmological probes in future. We study ability such surveys to constrain neutrino masses and equation state parameter dark energy, focusing on how tomographic information can improve sensitivity these parameters. also provide a detailed discussion systematic effects pertinent surveys, possible degradation parameters due effects. For future as Large Synoptic Survey Telescope survey, we find that, when combined with...
The matter power spectrum as derived from large scale structure (LSS) surveys contains two important and distinct pieces of information: an overall smooth shape the imprint baryon acoustic oscillations (BAO). We investigate separate impact these types information on cosmological parameter estimation for current data, show that simplest models, broad-band currently contained in SDSS DR7 halo (HPS) is by far superseded geometric baryonic features. An immediate corollary contrary to popular...
We use N-body simulations to find the effect of neutrino masses on halo properties, and investigate how density profiles both dark matter components change as a function mass. compare our with results from N-one-body method good agreement. also show explain why Tremaine-Gunn bound for neutrinos is not saturated. Finally, using we study mass changes Sheth-Tormen semi-analytic formulae. Our are important surveys which aim at probing cosmological parameters clusters, well future experiments...
Starting from the collisional Boltzmann equation, we derive for first time and principles hierarchy neutrinos including interactions with a scalar particle. Such appear, example, in majoron-like models of neutrino mass generation. We study two limits mass: (i) An extremely massive whose only role is to mediate an effective 4-fermion neutrino-neutrino interaction, (ii) massless that can be produced abundance thus demands its own hierarchy. In contrast to, e.g., first-order Thomson-scattering...
Abstract The impact of dark matter-neutrino interactions on the measurement cosmological parameters has been investigated in past context massless neutrinos exclusively. Here we revisit role a neutrino-dark matter coupling light ongoing tensions by implementing full Boltzmann hierarchy for three massive neutrinos. Our tightest 95% CL upper limit strength interactions, parameterized via u χ =σ 0 /σ Th (m /100 GeV) −1 , is ≤3.34 · 10 −4 arising from combination Planck TTTEEE data, lensing data...
Abstract We consider invisible neutrino decay $$\nu _H \rightarrow \nu _l + \phi $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>ν</mml:mi> <mml:mi>H</mml:mi> </mml:msub> <mml:mo>→</mml:mo> <mml:mi>l</mml:mi> <mml:mo>+</mml:mo> <mml:mi>ϕ</mml:mi> </mml:mrow> </mml:math> in the ultra-relativistic limit and compute anisotropy loss rate relevant for cosmic microwave background (CMB) anisotropies. Improving on our previous work which assumed massless...
We update cosmological hot dark matter constraints on neutrinos and hadronic axions. Our most restrictive limits use 7-year data from the Wilkinson Microwave Anisotropy Probe for cosmic microwave background anisotropies, halo power spectrum (HPS) 7th release of Sloan Digital Sky Survey, Hubble constant Space Telescope observations. find 95% CL upper ∑mν < 0.44 eV (no axions), ma 0.91 (assuming = 0), 0.41 0.72 two components after marginalising over respective other mass. CMB alone yield 1.19...