1,721,150 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Gamma-ray and neutrino diffuse emissions of the Galaxy above the TeV
No full textConventional cosmic ray propagation models face problems reproducing the diffuse γ-ray spectrum measured by Fermi-LAT over the entire sky. Those models also fail to smoothly connect Fermi-LAT results with data above the TeV as those taken by Milagro in the inner Galactic plane. In this contribution we show that a representative model adopting a spatial dependent rigidity scaling of the diffusion coefficient can reproduce all those experimental results without spoiling the consistency with local cosmic-ray measurements. We use the same model to compute the diffuse neutrino emission of the Galaxy and compare it with IceCube and ANTARES results
Antiproton constraints on the GeV gamma-ray excess: A comprehensive analysis
No full textA GeV gamma-ray excess has possibly been individuated in Fermi-LAT data from the Galactic Center and interpreted in terms of Dark Matter (DM) annihilations, either in hadronic (essentially bb) or leptonic channels. In order to test this tantalizing interpretation, we address two issues: (i) we improve the computation of secondary emission from DM (Inverse Compton and Bremsstrahlung) with respect to previous works, confirming it to be very relevant for determining the DM spectrum in the leptonic channels, so that any conclusion on the DM nature of the signal critically depends on this contribution; (ii) we consider the constraints from antiprotons on the DM hadronic channel, finding that the uncertainties on the propagation model, and in particular on the halo height, play a major role. Moreover, we discuss the role of solar modulation, taking into account possible charge dependent effects whose importance is estimated exploiting detailed numerical tools. The limits that we obtain severely constrain the DM interpretation of the excess in the hadronic channel, for standard assumptions on the Galactic propagation parameters and solar modulation. However, they considerably relax if more conservative choices are adopted
Diffuse Cosmic Rays Shining in the Galactic Center: A Novel Interpretation of H.E.S.S. and Fermi-LAT γ -Ray Data
No full textWe present a novel interpretation of the γ-ray diffuse emission measured by Fermi-LAT and H.E.S.S. in the Galactic center (GC) region and the Galactic ridge (GR). In the first part we perform a data-driven analysis based on PASS8 Fermi-LAT data: We extend down to a few GeV the spectra measured by H.E.S.S. and infer the primary cosmic-ray (CR) radial distribution between 0.1 and 3 TeV. In the second part we adopt a CR transport model based on a position-dependent diffusion coefficient. Such behavior reproduces the radial dependence of the CR spectral index recently inferred from the Fermi-LAT observations. We find that the bulk of the GR emission can be naturally explained by the interaction of the diffuse steady-state Galactic CR sea with the gas present in the central molecular zone. Although we confirm the presence of a residual radial-dependent emission associated with a central source, the relevance of the large-scale diffuse component prevents to claim a solid evidence of GC pevatrons
Gamma-ray and Neutrino Diffuse Emissions of the Galaxy at very High Energy
No full textSeveral independent analyzes of Fermi-LAT results found evidences of a spatial dependent cosmic ray (CR) spectral index which is not accounted for by conventional models of CR transport in the Galaxy. Moreover, several experiments have established the presence of a CR spectral hardening above few hundred GeV. We show that these results may have a relevant impact on the γ-ray and neutrino diffuse emissions of the Galaxy above the TeV. Indeed a phenomenological model which adopts a spatial dependent diffusion coefficient, so to account for those features, also reproduces the γ-ray excess found by Milagro at 15 TeV and the spectrum measured by H.E.S.S. and Fermi-LAT in the Galactic ridge. The same model predicts a neutrino emission along the Galactic plane which is significantly larger than expected on the basis of conventional models. This emission is compatible with ANTARES upper limits and is a natural target for KM3NeT
Human vs Robot Lie Detector: Better Working as a Team?
No full textHuman interaction often entails lies. Understanding when a partner is being deceitful is an important social skill, that also robots will need, to properly navigate social exchanges. In this work, we investigate how good are human observers at detecting false claims and which features they base their judgment on. Moreover, we compare their performance with that of an algorithm for lie detection developed for the robot iCub and based uniquely on pupillometry. We ran an online survey asking participants to classify as truthful or deceptive 20 videos of individuals describing complex drawings to iCub, either correctly or untruly. They also had to rate their confidence and provide a written motivation for each classification. Responders achieved an average accuracy of 53.9% with a higher score on detecting lies (55.4%) with respect to true statements (52.8%). Also, they performed better and more confidently on the videos iCub failed to classify than on the ones iCub correctly detected. Interestingly, the human observers listed a wide range of behavioral features as means to decide whether a speaker was lying, while the robot’s judgment was driven by pupil size only. This suggests that an avenue for improving lie detection could be a joint effort between humans and robots, where human sensitivity to subtle behavioral cues could complement the quantitative assessment of physiological signals feasible to the robot. Finally, based on the reported motivations, we speculate and give hints on how the lie detection field should evolve in the future, aiming to portability to real-world interactions
Gamma-ray sky points to radial gradients in cosmic-ray transport
No full textThe standard approach to cosmic-ray (CR) propagation in the Galaxy is based on the assumption that local transport properties can be extrapolated to the whole CR confining volume. Such models tend to underestimate the γ-ray flux above a few GeV measured by the Fermi Large Area Telescope toward the inner Galactic plane. We consider here for the first time a phenomenological scenario allowing for both the rigidity scaling of the diffusion coefficient and the convective effects to be position dependent. We show that within this approach we can reproduce the observed γ-ray spectra at both low and mid Galactic latitudes - including the Galactic center - without spoiling any local CR observable
THE GAMMA-RAY and NEUTRINO SKY: A CONSISTENT PICTURE of FERMI-LAT, MILAGRO, and ICECUBE RESULTS
No full textWe compute the γ-ray and neutrino diffuse emission of the Galaxy on the basis of a recently proposed phenomenological model characterized by radially dependent cosmic-ray (CR) transport properties. We show how this model, designed to reproduce both Fermi-LAT γ-ray data and local CR observables, naturally reproduces the anomalous TeV diffuse emission observed by Milagro in the inner Galactic plane. Above 100 TeV our picture predicts a neutrino flux that is about five (two) times larger than the neutrino flux computed with conventional models in the Galactic Center region (full-sky). Explaining in that way up to ∼25% of the flux measured by IceCube, we reproduce the full-sky IceCube spectrum adding an extra-Galactic component derived from the muonic neutrinos flux in the northern hemisphere. We also present precise predictions for the Galactic plane region where the flux is dominated by the Galactic emission
Towards a realistic astrophysical interpretation of the gamma-ray Galactic center excess
No full textA spherical-symmetric gamma-ray emission from {the inner region of the Galaxy (at least up to roughly 10° in latitude and longitude)} has been recently identified in Fermi-LAT data, and initially associated to dark matter particle annihilations. Guided by the evidence for a high gas density in the inner kpc of the Galaxy correlated with a very large Supernova rate, and hence with ongoing cosmic-ray acceleration, we investigate instead the possibility of addressing this excess in terms of ordinary cosmic-ray sources and standard steady-state diffusion. We {alter the source term, and consistently the correlated gamma-ray emissions, in the context of a template-fitting analysis. We focus on a region of interest (ROI) defined as: |l| < 20°; 2° < |b| < 20°, with l and b the Galactic longitude and latitude coordinates.} We analyze in detail the overall goodness of the fit of our framework, and perform a detailed direct comparison against data examining profiles in different directions. Remarkably, the test statistic of the fit related to our scenario turns out to be as good as the Dark Matter one in the ROI here considered
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