Constraining Galactic dark matter with gamma-ray pixel counts statistics

Gamma-ray searches for new physics such as dark matter are often driven by investigating the composition of the extragalactic gamma-ray background (EGB). Classic approaches to EGB decomposition manifest in resolving individual point sources and dissecting the intensity spectrum of the remaining unresolved component. Furthermore, statistical methods have recently been proven to outperform the sensitivity of classic source detection algorithms in finding point-source populations in the unresolved flux regime. In this article, we employ the 1-point photon count statistics of eight years of Fermi-LAT data to resolve the population of extragalactic point sources and to decompose the diffuse isotropic background contribution for Galactic latitudes |b|>30 deg. We use three adjacent energy bins between 1 and 10 GeV. For the first time, we extend the analysis to incorporate a potential contribution from annihilating dark matter smoothly distributed in the Galaxy. We investigate the sensitivity reach of 1-point statistics for constraining the thermally-averaged self-annihilation cross section of dark matter, using different template models for the Galactic foreground emission. Given the official Fermi-LAT interstellar emission model, we set upper bounds on the DM self-annihilation cross section that are comparable with the constraints obtained by other indirect detection methods, in particular by the stacking analysis of several dwarf spheroidal galaxies.Comment: 11 pages, 7 figures, 1 table; v2: major changes improving the selection of the RO

PACMAS: A Personalized, Adaptive, and Cooperative MultiAgent System Architecture

In this paper, a generic architecture, designed to support the implementation of applications aimed at managing information among different and heterogeneous sources, is presented. Information is filtered and organized according to personal interests explicitly stated by the user. User pro- files are improved and refined throughout time by suitable adaptation techniques. The overall architecture has been called PACMAS, being a support for implementing Personalized, Adaptive, and Cooperative MultiAgent Systems. PACMAS agents are autonomous and flexible, and can be made personal, adaptive and cooperative, depending on the given application. The peculiarities of the architecture are highlighted by illustrating three relevant case studies focused on giving a support to undergraduate and graduate students, on predicting protein secondary structure, and on classifying newspaper articles, respectively

Un caso di «economia morale» del primo Ottocento: il tumulto frumentario di Alghero del 1821

A Sardenya en els anys a cavall del ser i vuit-cents s'assisteix a un augment del nombre d’avalots relacionats amb l'exportació del forment sard, i per això tota sedició tenia com a fi el de boicotejar la sortida del blat cap a l’estranger. Era una època aquella en la qual s'estava imposant l’economia de mercat am la qual però entrava en crisi el model econòmic de l’ancien régime, de tipus paternalista, que en les conviccions del poble pertocava al rei i als seus representants el deure de disciplinar les provisions de blat i de queviures per a la població. L'economia morals deis pobres no reeixia a posar-se al dia i a adequar-se als mudaments del temps, tot invocant la norma fonamental que assegurava al poble la prioritat d'accés al blat produït per ell mateix dins el territori municipal. Heus ací explicades en síntesi, les raons dels tumults que, doncs, no tenien ara com a fi l’assalt als magatzems públics. on es dipositava el blat per a garantir el pa als més pobres, sinó l’atac als mercants privats responsables acaparadors del forment. En aquest marc s'explica també el que va passar a l'Alguer al 1821 de l’episodi del qual l'autor ofereix una documentació inèdita que complementa altres treballs ja apareguts dins aquesta mateixa revista sobre els tumults deis forment a l’Alguer

"De no poderse desmembrar la corona de Aragón": Sardenya i Països Catalans, un vincle de quatre segles

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Prima di tutto l'economia

Nell'agosto 1353, gli aragonesi s'impadronirono di Alghero. Una conquista tradizionalmente spiegata con la volontà dei conquistatori di poter contare su un'importante base navale. In realtà, la decisione fu determinata dalla volontà di mettere mano sul corallo, molto diffuso nei mari tra Bosa e l'Asinara. L'obiettivo fu raggiunto ed i mercanti catalani conservarono a lungo il monopolio di quella risorsa

L'"Ispanizzazione" della Sardegna: un bilancio

Sommario: 1. Un avvio complicato e difficile. - 2. La "costruzione" del regno. - 3. Un'integrazione politica e culturale profonda e duratura. - 4. "Una provincia della Spagna". - 5. Una tradizione culturale intrecciata e complessa. - 6. Una "leggenda nera"

Multi-messenger constraints to the local emission of cosmic-ray electrons

The data on the inclusive flux of cosmic positrons and electrons ($e^++e^{-}$) have been recently collected from GeV to tens of TeV energies by several experiments with unprecedented precision. In addition, the Fermi-LAT Collaboration has provided a new energy spectrum for the upper bounds on the $e^++e^{-}$ dipole anisotropy. This observable can bring information on the emission from local Galactic sources, notably measured with high precision at radio frequencies. We develop a framework in which $e^-$ and $e^+$ measured at Earth from GeV up to tens of TeV energies have a composite origin. A dedicated analysis is deserved to Vela YZ and Cygnus Loop Supernova Remnants (SNRs), for which we consider two different models for the injection of $e^-$. We investigate the consistency of these models using the three physical observables: the radio flux from Vela YZ and Cygnus Loop at all the available frequencies, the $e^++e^-$ flux from five experiments from the GeV to tens of TeV energy, the $e^++e^-$ dipole anisotropy upper limits from 50 GeV to about 1 TeV. We find that the radio flux for these nearby SNRs strongly constraints the properties of the injection electron spectrum, partially compatible with the looser constraints derived from the $e^+ + e^-$ flux data. We also perform a multi-wavelength multi-messenger analysis by fitting simultaneously the radio flux on Vela YZ and Cygnus Loop and the $e^+ + e^-$ flux, and checking the outputs against the $e^+ + e^-$ dipole anisotropy data. Remarkably, we find a model which is compatible with all the $e^++e^-$ flux data, the radio data for Vela YZ and Cygnus Loop, and with the anisotropy upper bounds. We show the severe constraints imposed by the most recent data on the $e^+ + e^-$ dipole anisotropy.Comment: 20 pages, 9 figures. Accepted for publication in the JCAP. Changes in v3: discussion and results extended to include an evolutionary model for the injection of cosmic-ray electrons in SNR

Dal 1848 agli anni del fascismo

La storia della provincia di Sassari dalla sua nascita fino all'avvento del fascismo: la politica, la situazione di pastori e contadini, i progressisti moderati, l'età giolittiana, la grande guerra

Vita e imprese di Geronimo Ferret. Un soldalo algherese al servizio del Re di Spagna

El contingut d’aquest assaig està relacionat amb la descoberta, a l’Arxiu de la Corona d’Aragó, d’uns documents relatius a Don Hieroni Ferret, inclós el "curriculum vitae" amb el qual el militar alguerès, a raó de la seva fidelitat i dels serveis oferts a la causa reial, fa instància perquè li vengui atorgat el grau nobiliari corresponent. El fet curiós és que el mateix Ferret postula el mateix estatus nobiliari per a dos dels seu s nebots Francesc i Gaví —aquests també militars, però amb un escàs "currículum vitae". L’autobiografia del Capità Don Hieroni Ferret és de debò molt interessant car ofereix una visió totalment inèdita d’un personatge que a l’aventura militar va dedicar tota la vida no sense haver acumulat moltes riqueses. L’extravagant personatge, tanmateix, a punt de morir va ser molt generós amb els pobres i els orfes de la seva ciutat; gràcies a ell els jesuïtes van poder dur a terme l’edificació de llur "Col·legi" i de l’annexa Església de Sant Miquel" on el mateix personatge va tenir sepultura. Una destacada i original làpida mortuòria, en marbre policrom, recorda a l’esdevenidor

“Para los reales exércitos de su magestad”. La aportación de la nobleza sarda a las guerras de la monarquía hispánica (1626-1652).

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