37 research outputs found

    Search for muon-neutrino emission from GeV and TeV gamma-ray flaring blazars using five years of data of the ANTARES telescope

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    The ANTARES telescope is well-suited for detecting astrophysical transient neutrino sources as it can observe a full hemisphere of the sky at all times with a high duty cycle. The background due to atmospheric particles can be drastically reduced, and the point-source sensitivity improved, by selecting a narrow time window around possible neutrino production periods. Blazars, being radio-loud active galactic nuclei with their jets pointing almost directly towards the observer, are particularly attractive potential neutrino point sources, since they are among the most likely sources of the very high-energy cosmic rays. Neutrinos and gamma rays may be produced in hadronic interactions with the surrounding medium. Moreover, blazars generally show high time variability in their light curves at different wavelengths and on various time scales. This paper presents a time-dependent analysis applied to a selection of flaring gamma-ray blazars observed by the FERMI/LAT experiment and by TeV Cherenkov telescopes using five years of ANTARES data taken from 2008 to 2012. The results are compatible with fluctuations of the background. Upper limits on the neutrino fluence have been produced and compared to the measured gamma-ray spectral energy distribution.Comment: 27 pages, 16 figure

    Search for muon-neutrino emission from GeV and TeV gamma-ray flaring blazars using five years of data of the ANTARES telescope

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    The ANTARES telescope is well-suited for detecting astrophysical transient neutrino sources as it can observe a full hemisphere of the sky at all times with a high duty cycle. The background due to atmospheric particles can be drastically reduced, and the point-source sensitivity improved, by selecting a narrow time window around possible neutrino production periods. Blazars, being radio-loud active galactic nuclei with their jets pointing almost directly towards the observer, are particularly attractive potential neutrino point sources, since they are among the most likely sources of the very high-energy cosmic rays. Neutrinos and gamma rays may be produced in hadronic interactions with the surrounding medium. Moreover, blazars generally show high time variability in their light curves at different wavelengths and on various time scales. This paper presents a time-dependent analysis applied to a selection of flaring gamma-ray blazars observed by the FERMI/LAT experiment and by TeV Cherenkov telescopes using five years of ANTARES data taken from 2008 to 2012. The results are compatible with fluctuations of the background. Upper limits on the neutrino fluence have been produced and compared to the measured gamma-ray spectral energy distributionThe authors acknowledge the financial support of the funding agencies: Centre National de la Recherche Scientifique (CNRS), Commissariat a l'energie atomique et aux energies alternatives (CEA), Commission Europeenne (FEDER fund and Marie Curie Program), Region Ile-de-France (DIM-ACAV) Region Alsace (contrat CPER), Region Provence-Alpes-Cote d'Azur, Departement du Var and Ville de La Seyne-sur-Mer, France; Bundesministerium fur Bildung und Forschung (BMBF), Germany; Istituto Nazionale di Fisica Nucleare (INFN), Italy; Stichting voor Fundamenteel Onderzoek der Materie (FOM), Nederlandse organisatie voor Wetenschappelijk Onderzoek (NWO), the Netherlands; Council of the President of the Russian Federation for young scientists and leading scientific schools supporting grants, Russia; National Authority for Scientific Research (ANCS), Romania; Ministerio de Economia y Competitividad (MINECO), Prometeo and Grisolia programs of Generalitat Valenciana and MultiDark, Spain; Agence de l'Oriental and CNRST, Morocco. We also acknowledge the technical support of Ifremer, AIM and Foselev Marine for the sea operation and the CC-IN2P3 for the computing facilities.Adrián Martínez, S.; Albert, A.; André, M.; Anton, G.; Ardid Ramírez, M.; Aubert, J.; Baret, B.... (2015). Search for muon-neutrino emission from GeV and TeV gamma-ray flaring blazars using five years of data of the ANTARES telescope. Journal of Cosmology and Astroparticle Physics. 12(14):1-26. https://doi.org/10.1088/1475-7516/2015/12/014S1261214Becker, J. K. (2008). High-energy neutrinos in the context of multimessenger astrophysics. Physics Reports, 458(4-5), 173-246. doi:10.1016/j.physrep.2007.10.006Bloom, S. D., & Marscher, A. P. (1996). An Analysis of the Synchrotron Self-Compton Model for the Multi--Wave Band Spectra of Blazars. The Astrophysical Journal, 461, 657. doi:10.1086/177092Maraschi, L., Ghisellini, G., & Celotti, A. (1992). A jet model for the gamma-ray emitting blazar 3C 279. 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    Longer and better lives for patients with atrial fibrillation:the 9th AFNET/EHRA consensus conference

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    Aims: Recent trial data demonstrate beneficial effects of active rhythm management in patients with atrial fibrillation (AF) and support the concept that a low arrhythmia burden is associated with a low risk of AF-related complications. The aim of this document is to summarize the key outcomes of the 9th AFNET/EHRA Consensus Conference of the Atrial Fibrillation NETwork (AFNET) and the European Heart Rhythm Association (EHRA). Methods and results: Eighty-three international experts met in Münster for 2 days in September 2023. Key findings are as follows: (i) Active rhythm management should be part of the default initial treatment for all suitable patients with AF. (ii) Patients with device-detected AF have a low burden of AF and a low risk of stroke. Anticoagulation prevents some strokes and also increases major but non-lethal bleeding. (iii) More research is needed to improve stroke risk prediction in patients with AF, especially in those with a low AF burden. Biomolecules, genetics, and imaging can support this. (iv) The presence of AF should trigger systematic workup and comprehensive treatment of concomitant cardiovascular conditions. (v) Machine learning algorithms have been used to improve detection or likely development of AF. Cooperation between clinicians and data scientists is needed to leverage the potential of data science applications for patients with AF. Conclusions: Patients with AF and a low arrhythmia burden have a lower risk of stroke and other cardiovascular events than those with a high arrhythmia burden. Combining active rhythm control, anticoagulation, rate control, and therapy of concomitant cardiovascular conditions can improve the lives of patients with AF

    Oral anticoagulation in device-detected atrial fibrillation: effects of age, sex, cardiovascular comorbidities, and kidney function on outcomes in the NOAH-AFNET 6 trial.

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    Implanted pacemakers, defibrillators, and loop recorders detect short and rare episodes of device-detected atrial fibrillation [DDAF, previously also called atrial high-rate episodes or subclinical atrial fibrillation (AF)] in ∼30% of patients. Device-detected atrial fibrillation rarely has therapeutic consequences in patients with ECG-documented AF. Device-detected atrial fibrillation without ECG-documented AF can lead to consideration of oral anticoagulation in clinical practice, especially in older patients with multiple stroke risk factors and/or very long DDAF episodes, largely based on observational data. Two recent controlled trials, NOAH-AFNET 6 and ARTESiA, observed a low rate of ischaemic stroke without anticoagulation (1.1%–1.2%/patient-year) in patients with DDAF and stroke risk factors, including in patients with very long DDAF episodes in NOAH-AFNET 6. Current guidelines leave the decision to anticoagulate to clinical judgement, balancing the expected stroke risk, typically estimated by using stroke risk scores developed in patients with ECG-documented AF, and the stroke risk reduction induced by anticoagulation, with the increase in bleeding associated with anticoagulation therapy
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