Transport of exotic anti-nuclei: I- Fast formulae for antiproton fluxes

The Galactic secondary cosmic ray anti-proton flux calculated with different propagation models is fairly consistent with data, and the associated propagation uncertainty is small. This is not the case for any anti-proton exotic component of the dark matter halo. Detailed propagation models are mandatory if the ultimate goal is to explain an excess. However, simpler and faster approximate formulae for anti-protons are an attractive alternative to quickly check that a given dark matter model is not inconsistent with the anti-proton observed flux. This paper provides such formulae. In addition, they could be used to put constraints on new physics in this channel, where an extensive scan of a large parameter space could otherwise be quite expensive in computer ressources.Comment: 8 pages, 3 figures (submitted). Stand-alone code for exotic anti-proton propagation can be downloaded at http://wwwlapp.in2p3.fr/~taillet/mtc/mtc_code.tar . Paper re-organized (results unchanged

A Markov Chain Monte Carlo technique to sample transport and source parameters of Galactic cosmic rays: II. Results for the diffusion model combining B/C and radioactive nuclei

On-going measurements of the cosmic radiation (nuclear, electronic, and gamma-ray) are shedding new light on cosmic-ray physics. A comprehensive picture of these data relies on an accurate determination of the transport and source parameters of propagation models. A Markov Chain Monte Carlo is used to obtain these parameters in a diffusion model. From the measurement of the B/C ratio and radioactive cosmic-ray clocks, we calculate their probability density functions, with a special emphasis on the halo size L of the Galaxy and the local underdense bubble of size r_h. The analysis relies on the USINE code for propagation and on a Markov Chain Monte Carlo technique (Putze et al. 2009, paper I of this series) for the parameter determination. As found in previous studies, the B/C best-fit model favours diffusion/convection/reacceleration (Model III) over diffusion/reacceleration (Model II). A combined fit on B/C and the isotopic ratios (10Be/9Be, 26Al/27Al, 36Cl/Cl) leads to L ~ 8 kpc and r_h ~ 120 pc for the best-fit Model III. This value for r_h is consistent with direct measurements of the local interstallar medium. For Model II, L ~ 4 kpc and r_h is consistent with zero. We showed the potential and usefulness of the Markov Chain Monte Carlo technique in the analysis of cosmic-ray measurements in diffusion models. The size of the diffusive halo depends crucially on the value of the diffusion slope delta, and also on the presence/absence of the local underdensity damping effect on radioactive nuclei. More precise data from on-going experiments are expected to clarify this issue.Comment: 20 pages, 14 figures, minor language corrections to match the A&A accepted versio

CLUMPY: a code for gamma-ray signals from dark matter structures

We present the first public code for semi-analytical calculation of the gamma-ray flux astrophysical J-factor from dark matter annihilation/decay in the Galaxy, including dark matter substructures. The core of the code is the calculation of the line of sight integral of the dark matter density squared (for annihilations) or density (for decaying dark matter). The code can be used in three modes: i) to draw skymaps from the Galactic smooth component and/or the substructure contributions, ii) to calculate the flux from a specific halo (that is not the Galactic halo, e.g. dwarf spheroidal galaxies) or iii) to perform simple statistical operations from a list of allowed DM profiles for a given object. Extragalactic contributions and other tracers of DM annihilation (e.g. positrons, antiprotons) will be included in a second release.Comment: 15 pages, 7 figures, published in CPC. The CLUMPY code and its documentation can be found at http://lpsc.in2p3.fr/clump

CRDB: a database of charged cosmic rays

This paper gives a description of a new on-line database http://lpsc.in2p3.fr/crdb and associated on-line tools (data selection, data export, plots, etc.) for charged cosmic-ray measurements. The experimental setups (type, flight dates, techniques) from which the data originate are included in the database, along with the references to all relevant publications. The database relies on the MySQL5 engine. The web pages and queries are based on PHP, AJAX and the jquery, jquery.cluetip, jquery-ui, and table-sorter third-party libraries. In this first release, we restrict ourselves to Galactic cosmic rays with Z<=30 and a kinetic energy per nucleon up to a few tens of TeV/n. This corresponds to more than 200 different sub-experiments (i.e., different experiments, or data from the same experiment flying at different times) in as many publications. We set up a cosmic-ray database and provide tools to sort and visualise the data. New data can be submitted, providing the community with a collaborative tool to archive past and future cosmic-ray measurements. Any help/ideas to further expand and/or complement the database is welcome (please contact [email protected]).Comment: 13 pages, 6 figures: new Sect. 2.3 on Solar modulation parameters in CRDB v2.1, see http://lpsc.in2p3.fr/crd

Contamination of stellar-kinematic samples and uncertainty about dark matter annihilation profiles in ultrafaint dwarf galaxies: the example of Segue I

The expected gamma-ray flux coming from dark matter annihilation in dwarf spheroidal (dSph) galaxies depends on the so-called `J-factor', the integral of the squared dark matter density along the line-of-sight. We examine the degree to which estimates of J are sensitive to contamination (by foreground Milky Way stars and stellar streams) of the stellar-kinematic samples that are used to infer dark matter densities in `ultrafaint' dSphs. Applying standard kinematic analyses to hundreds of mock data sets that include varying levels of contamination, we find that mis-classified contaminants can cause J-factors to be overestimated by orders of magnitude. Stellar-kinematic data sets for which we obtain such biased estimates tend 1) to include relatively large fractions of stars with ambiguous membership status, and 2) to give estimates for J that are sensitive to specific choices about how to weight and/or to exclude stars with ambiguous status. Comparing publicly-available stellar-kinematic samples for the nearby dSphs Reticulum~II and Segue~I, we find that only the latter displays both of these characteristics. Estimates of Segue~I's J-factor should therefore be regarded with a larger degree of caution when planning and interpreting gamma-ray observations. Moreover, robust interpretations regarding dark matter annihilation in dSph galaxies in general will require explicit examination of how interlopers might affect the inferred dark matter density profile.Comment: 12 pages, 8 figures. New appendix A (joint light/dark matter likelihood), results unchanged. Match accepted MNRAS versio

Nuclear Cosmic Rays propagation in the Atmosphere

The transport of the nuclear cosmic ray flux in the atmosphere is studied and the atmospheric corrections to be applied to the measurements are calculated. The contribution of the calculated corrections to the accuracy of the experimental results are discussed and evaluated over the kinetic energy range 10-10$^{3}$ GeV/n. The Boron (B) and Carbon (C) elements system is used as a test case. It is shown that the required corrections become largely dominant at the highest energies investigated. The results are discussed.Comment: Proc. of 30th International Cosmic Ray Conference, Merida, Mexico; 4 page

USINE: a new public cosmic-ray propagation code (Basic Phenomenology, Sample Results, and a Bit of USINE)

Astroparticle, Particle, Space Physics, Radiation Interaction, Detectors and Medical Physics Applications - Vol. 6 ISBN: 978-981-4329-02-6International audienc

Spherical Jeans analysis for dark matter indirect detection in dwarf spheroidal galaxies - Impact of physical parameters and triaxiality

Dwarf spheroidal (dSph) galaxies are among the most promising targets for the indirect detection of dark matter (DM) from annihilation and/or decay products. Empirical estimates of their DM content - and hence the magnitudes of expected signals - rely on inferences from stellar-kinematic data. However, various kinematic analyses can give different results and it is not obvious which are most reliable. Using extensive sets of mock data of various sizes (mimicking 'ultra-faint' and 'classical' dSphs) and an MCMC engine, here we investigate biases, uncertainties, and limitations of analyses based on parametric solutions to the spherical Jeans equation. For a variety of functional forms for the tracer and DM density profiles, as well as the orbital anisotropy profile, we examine reliability of estimates for the astrophysical J- and D-factors for annihilation and decay, respectively. For large (N > 1000) stellar-kinematic samples typical of 'classical' dSphs, errors tend to be dominated by systematics, which can be reduced through the use of sufficiently general and flexible functional forms. For small (N < 100) samples typical of 'ultrafaints', statistical uncertainties tend to dominate systematic errors and flexible models are less necessary. We define an optimal strategy that would mitigate sensitivity to priors and other aspects of analyses based on the spherical Jeans equation. We also find that the assumption of spherical symmetry can bias estimates of J (with the 95% credibility intervals not encompassing the true J-factor) when the object is mildly triaxial (axis ratios b/a = 0.8, c/a = 0.6). A concluding table summarises the typical error budget and biases for the different sample sizes considered.Comment: 21 pages, 20 figures. Minor changes (several clarifications): match the MNRAS accepted versio