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

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

Galactic secondary positron flux at the Earth

Secondary positrons are produced by spallation of cosmic rays within the interstellar gas. Measurements have been typically expressed in terms of the positron fraction, which exhibits an increase above 10 GeV. Many scenarios have been proposed to explain this feature, among them some additional primary positrons originating from dark matter annihilation in the Galaxy. The PAMELA satellite has provided high quality data that has enabled high accuracy statistical analyses to be made, showing that the increase in the positron fraction extends up to about 100 GeV. It is therefore of paramount importance to constrain theoretically the expected secondary positron flux to interpret the observations in an accurate way. We find the secondary positron flux to be reproduced well by the available observations, and to have theoretical uncertainties that we quantify to be as large as about one order of magnitude. We also discuss the positron fraction issue and find that our predictions may be consistent with the data taken before PAMELA. For PAMELA data, we find that an excess is probably present after considering uncertainties in the positron flux, although its amplitude depends strongly on the assumptions made in relation to the electron flux. By fitting the current electron data, we show that when considering a soft electron spectrum, the amplitude of the excess might be far lower than usually claimed. We provide fresh insights that may help to explain the positron data with or without new physical model ingredients. PAMELA observations and the forthcoming AMS-02 mission will allow stronger constraints to be aplaced on the cosmic--ray transport parameters, and are likely to reduce drastically the theoretical uncertainties.Comment: 15 pages, 12 figures. The recent PAMELA data on the positron fraction (arXiv:0810.4995) have been included and the ensuing discussion has been extended. Accepted version in A&

Decaying dark matter: a stacking analysis of galaxy clusters to improve on current limits

We show that a stacking approach to galaxy clusters can improve current limits on decaying dark matter by a factor $\gtrsim 5-100$, with respect to a single source analysis, for all-sky instruments such as Fermi-LAT. Based on the largest sample of X-ray-selected galaxy clusters available to date (the MCXC meta-catalogue), we provide all the astrophysical information, in particular the astrophysical term for decaying dark matter, required to perform an analysis with current instruments.Comment: 6 pages, 3 figures, supplementary file available on demand, accepted for publication in PR

Désaisonnalisation des agrégats monétaires : Mise en place d’une chaîne rénovée.

The analysis of seasonality in economics and the development of new seasonal adjustment procedures have been following new directions in the last twenty years. We study this question through the work performed at the Banque de France (Monetary Statistic and Studies Directorate) to compile new seasonally adjusted (SA) data. A brief discussion of the academic literature show the necessity to complement the existing software with empirical rules fixed by the practitioner in order to make all the methodological choices clear, thus avoiding any ambiguity. In the implementation of the new production process, we focus on the revision policy of some keys parameters of the whole process in order to minimize the subsequent revisions in the publication of SA data. We illustrate this new methodology with SA series relating to monetary aggregates, including loans to enterprises and to households, and provide a detailed analysis of the consistency between flows and outstanding amount SA figures, an issue particularly relevant for monetary an financial data.Seasonal Adjustment Methods ; Monetary Aggregates ; Outliers ; SARIMA Models ; Spectral Analysis.

Spatial Origin of Galactic Cosmic Rays in Diffusion Models: I- Standard sources in the Galactic disk

The propagation of Galactic Cosmic Ray nuclei having energies between 100 MeV/nuc and several PeV/nuc is strongly believed to be of diffusive nature. The particles emitted by a source located in the disk do not pervade the whole Galaxy, but are rather confined to a smaller region whose spatial extension is related to the height of the diffusive halo, the Galactic wind and the spallation rate. Following the pioneering work of Jones (1978), this paper presents a general study on the spatial origin of cosmic rays, with a particular attention to the role of spallations and Galactic wind. This question is different, and to a certain extent disconnected, from that of the origin of cosmic rays. We find the regions of the disk from which a given fraction of cosmic rays detected in the Solar neighborhood were emitted (f-surfaces). After a general study, we apply the results to a realistic source distribution, with the propagation parameters obtained in our previous systematic analysis of the observed secondary-to-primary ratios Maurin et al (2002). The shape and size of these f-surfaces depend on the species as well as on the values of the propagation parameters. For some of the models preferred by our previous analysis (i.e. large diffusion slope $\delta$), these f-surfaces are small and in some extreme cases only a fraction of a percent of the whole Galactic sources actually contribute to the Solar neighborhood Cosmic Ray flux. Moreover, a very small number of sources may be responsible for more than 15 % of the flux detected in the Solar neighborhood. This may point towards the necessity to go beyond the approximations of both homogeneity and stationarity. Finally, the observed primary composition is dominated by sources within a few kpc.Comment: revised version, 32 pages, to appear in A&A. Shortened version, with corresction

Sensitivity studies for the cubic-kilometre deep-sea neutrino telescope KM3NeT

The observation of high-energy neutrinos from astrophysical sources would substantially improve our knowledge and understanding of the non-thermal processes in these sources, and would in particular pinpoint the accelerators of cosmic rays. The sensitivity of different design options for a future cubic-kilometre scale neutrino telescope in the Mediterranean Sea is investigated for generic point sources and in particular for some of the galactic objects from which TeV gamma emmission has recently been observed by the H.E.S.S. atmospheric Cherenkov telescope. The effect of atmospheric background on the source detection probabilities has been taken into account through full simulation. The estimated event rates are compared to previous results and limits from present neutrino telescopes.Comment: 4 pages, 1 figure, contribution of the 30th International Cosmic Ray conferenc

Variation of the X-ray non-thermal emission in the Arches cloud

The origin of the iron fluorescent line at 6.4 keV from an extended region surrounding the Arches cluster is debated and the non-variability of this emission up to 2009 has favored the low-energy cosmic-ray origin over a possible irradiation by hard X-rays. By probing the variability of the Arches cloud non-thermal emission in the most recent years, including a deep observation in 2012, we intend to discriminate between the two competing scenarios. We perform a spectral fit of XMM-Newton observations collected from 2000 to 2013 in order to build the Arches cloud lightcurve corresponding to both the neutral Fe Kalpha line and the X-ray continuum emissions. We reveal a 30% flux drop in 2012, detected with more than 4 sigma significance for both components. This implies that a large fraction of the studied non-thermal emission is due to the reflection of an X-ray transient source.Comment: 5 pages, 3 figures, accepted for publication in MNRAS Letter

New results on source and diffusion spectral features of Galactic cosmic rays: I- B/C ratio

In a previous study (Maurin et al., 2001), we explored the set of parameters describing diffusive propagation of cosmic rays (galactic convection, reacceleration, halo thickness, spectral index and normalization of the diffusion coefficient), and we identified those giving a good fit to the measured B/C ratio. This study is now extended to take into account a sixth free parameter, namely the spectral index of sources. We use an updated version of our code where the reacceleration term comes from standard minimal reacceleration models. The goal of this paper is to present a general view of the evolution of the goodness of fit to B/C data with the propagation parameters. In particular, we find that, unlike the well accepted picture, and in accordance with our previous study, a Kolmogorov-like power spectrum for diffusion is strongly disfavored. Rather, the $\chi^2$ analysis points towards $\delta\gtrsim 0.7$ along with source spectra index $\lesssim 2.0$. Two distinct energy dependences are used for the source spectra: the usual power-law in rigidity and a law modified at low energy, the second choice being only slightly preferred. We also show that the results are not much affected by a different choice for the diffusion scheme. Finally, we compare our findings to recent works, using other propagation models. This study will be further refined in a companion paper, focusing on the fluxes of cosmic ray nuclei.Comment: 32 pages, 13 figures, accepted in A&