2,097 research outputs found

    Extragalactic gamma-ray background from AGN winds and star-forming galaxies in cosmological galaxy formation models

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    We derive the contribution to the extragalactic gamma-ray background (EGB) from AGN winds and star-forming galaxies by including a physical model for the gamma-ray emission produced by relativistic protons accelerated by AGN-driven and supernova-driven shocks into a state-of-the-art semi-analytic model of galaxy formation. This is based on galaxy interactions as triggers of AGN accretion and starburst activity and on expanding blast wave as the mechanism to communicate outwards the energy injected into the interstellar medium by the active nucleus. We compare the model predictions with the latest measurement of the EGB spectrum performed by the Fermi-LAT in the range between 100 MeV and 820 GeV. We find that AGN winds can provide ~35±\pm15% of the observed EGB in the energy interval E_{\gamma}=0.1-1 GeV, for ~73±\pm15% at E_{\gamma}=1-10 GeV, and for ~60±\pm20% at E_{\gamma}>10 GeV. The AGN wind contribution to the EGB is predicted to be larger by a factor of 3-5 than that provided by star-forming galaxies (quiescent plus starburst) in the hierarchical clustering scenario. The cumulative gamma-ray emission from AGN winds and blazars can account for the amplitude and spectral shape of the EGB, assuming the standard acceleration theory, and AGN wind parameters that agree with observations. We also compare the model prediction for the cumulative neutrino background from AGN winds with the most recent IceCube data. We find that for AGN winds with accelerated proton spectral index p=2.2-2.3, and taking into account internal absorption of gamma-rays, the Fermi-LAT and IceCube data could be reproduced simultaneously.Comment: 12 pages, 8 figures, accepted for publication in A&

    Astreintes and Italian Law

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    This essay analyses the transposition path into Italian law of the French measure of astreintes, which are an indirect coercive method aimed to force the debtor to fulfill the obligation. The modern configuration has led to the adoption of judgments such as the one related to the “Case Facebook” (Order of the Court of Reggio Emilia, 15 April 2015), involving the urgency protection provided by art. 700 c.c.p. relatively to the hypothesis of defamation on Facebook or other Social Networking Sites. The astreinte find an equal in the Anglo-Saxon sort, by the contempt of court, and in the German one, through the Zwangsstrafen, which led, after several transposition attempts into national law (among which stands out the “Project Carnelutti” of 1926), to the current forecast referred to art. 614 bis c.c.p., introduced by art. 49 of Law 18 June 2009 n. 69. An application issue of the astreinte in Italy concerns its potential struggle with the internal public order: in Italy, there isn’t any provision of punitive damages outlined in common law systems, so that their transposition would lead to a worsening of the obliged subject's position, in contrast with the proportionality principle on which is based the compensation statement system. The Italian Supreme Court, by the judgment of 15 April 2015 n. 7283, expresses itself in the opposite direction, stating that “the astreintes provided in other jurisdictions […] are not incompatible with the Italian public policy”. The contemporary Italian law framework, based on the right of “forced execution”, which one can deduct from the art. 24 of the Constitution (which states that all may take legal action for protecting their rights and legitimate interests), is outlined from the Book III, Title IV of the Italian Code of Civil Procedure, indexed “the enforcement of proactive or passive obligations”, Articles 612 to 614 bis c.c.p., where it is possible to involve, from the address of the art. 614 bis c.c.p., the irreplaceable performance, although the same rule has generated several disputes. To underline the value and the transverse projection of the theme, it is proper to highlight the inapplicability of Article 614 bis c.c.p. to individual work disputes listed in art. 409 c.c.p. This exclusion, unjustified and irrational, strongly undermines the principle of equality safeguarded by the art. 3 of the Italian Constitutional Charter, and has given rise to an abundant doctrine that considered art. 614 bis c.c.p., if applied, an extra protection to the right to work contemplated by the art. 4 of the Constitution, and even by art. 18 L. 20 May 1970 n. 300. In this perspective, the art. 614 bis make up a missed opportunity for the code of civil procedure to ensure an executive procedural protection for both parties of the employment contract. The possible reconstructions related to debtor's indirect coercion shows problematic aspects referring to a potential overlap with ordinary protection instruments provided by Articles 1223 c.c., indexed “compensation of the damage”, and 2932 c.c., indexed “specific execution of the obligation to close a contract”, which, for certain doctrine, would be posed after the means provided by art. 614 bis c.c.p. In this way, the executive safeguards to the damage resulting from the breach would be erroneously duplicated. For certain doctrine, this impasse could be overcome by the second paragraph of this Article, with a factual assessment, carried out by the Court, of the abovementioned principle of irreplaceability, excluding its application to all those obligations deprived of such connotation. Some doctrine opposed another configuration, endorsed by the jurisprudence, which postulates a systematic and teleological interpretation, per which it would be possible to extend such protection independently from a postulate of irreplaceability. In this scenario, the research will, at last, offer an interesting train of thought to the debate on legal affairs in the perspective of a possible future and further reform of the civil execution law, also taking into consideration to transpose into Italian Law an institute inspired by punitive damages and based on the penal principle of rehabilitation function of punishment (rectius, in this case, of execution) referred to art. 27 subparagraph 3 of the Italian Constitution

    A novel MPGD-based Hadronic Calorimeter for Muon Collider experiments

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    The Multi-TeV Muon Collider is proposed as a promising tool for advancement in understanding the Standard Model within the European particle physics strategy. The Muon Collider physics program focuses on precise measure- ments in the Higgs boson sector and exploring new physics at the TeV scale. Achiev- ing these goals requires accurate full-event reconstruction, with the Particle Flow (PF) algorithm as a suitable approach. This algorithm utilizes information from tracking, calorimeter, and muon detectors for particle identification and momen- tum/energy measurements. The challenge lies in discriminating μμ collision prod- ucts from the intense beam-induced background (BIB) due to the unstable nature of muons. To address this, an innovative hadronic calorimeter (HCAL) based on Mi- cro Pattern Gas Detectors (MPGDs) is proposed. MPGDs offer robust technology for high radiation environments and high granularity for precise spatial measure- ments. Dedicated studies are needed to assess and optimize the performance of the MPGD-based HCAL, including developing prototypes as proof of concept. Monte Carlo simulations using Geant4 evaluate the HCAL’s response to incoming parti- cles, comparing digital and semi-digital readouts with energy resolution as the key metric. The simulated geometry is integrated into the Muon Collider software to analyze its impact on jet reconstruction amid the full apparatus and in the pres- ence of BIB. Validation involves testing a small-size calorimeter cell equipped with resistive MPGD technologies like MicroMegas, μRWELL, and RP-WELL

    ASTRI SST-2M prototype and mini-array simulation chain, data reduction software, and archive in the framework of the Cherenkov Telescope Array

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    The Cherenkov Telescope Array (CTA) is a worldwide project aimed at building the next-generation ground-based gamma-ray observatory. Within the CTA project, the Italian National Institute for Astrophysics (INAF) is developing an end-to-end prototype of the CTA Small-Size Telescopes with a dual-mirror (SST-2M) Schwarzschild-Couder configuration. The prototype, named ASTRI SST-2M, is located at the INAF "M.C. Fracastoro" observing station in Serra La Nave (Mt. Etna, Sicily) and is currently in the scientific and performance validation phase. A mini-array of (at least) nine ASTRI telescopes has been then proposed to be deployed at the Southern CTA site, by means of a collaborative effort carried out by institutes from Italy, Brazil, and South-Africa. The CTA/ASTRI team is developing an end-to-end software package for the reduction of the raw data acquired with both ASTRI SST-2M prototype and mini-array, with the aim of actively contributing to the global ongoing activities for the official data handling system of the CTA observatory. The group is also undertaking a massive Monte Carlo simulation data production using the detector Monte Carlo software adopted by the CTA consortium. Simulated data are being used to validate the simulation chain and evaluate the ASTRI SST-2M prototype and mini-array performance. Both activities are also carried out in the framework of the European H2020-ASTERICS (Astronomy ESFRI and Research Infrastructure Cluster) project. A data archiving system, for both ASTRI SST-2M prototype and mini-array, has been also developed by the CTA/ASTRI team, as a testbed for the scientific archive of CTA. In this contribution, we present the main components of the ASTRI data handling systems and report the status of their development.Comment: Proceedings of the 35th International Cosmic Ray Conference (ICRC 2017), Bexco, Busan, Korea. All CTA contributions at arXiv:1709.0348

    Multiwavelength observation from radio through very-high-energy Gamma-ray of OJ 287 during the 12-year cycle flare in 2007

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    We performed simultaneous multiwavelength observations of OJ 287 with the Nobeyama Millimeter Array for radio, the KANATA telescope and the KVA telescope for optical, the Suzaku satellite for X-ray and the MAGIC telescope for very high energy (VHE) gamma-ray in 2007. The observations were conducted for a quiescent state in April and in a flaring state in November-December. We clearly observed increase of fluxes from radio to X-ray bands during the flaring state while MAGIC could not detect significant VHE gamma-ray emission from the source. We could derive an upper limit (95% confidence level) of 1.7% of the Crab Nebula flux above 150 GeV from about 41.2 hours of the MAGIC observation. A simple SSC model suggests that the observed flaring activity could be caused by evolutions in the distribution of the electron population rather than changes of the magnetic field strength or Doppler beaming factor in the jet.Comment: Contribution to the 31st ICRC, Lodz, Poland, July 200
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