SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Almeida J. R. C.) "

Sökning: WFRF:(Almeida J. R. C.)

Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Acciari, V. A., et al. (författare)
  • Radio Imaging of the Very-High-Energy gamma-Ray Emission Region in the Central Engine of a Radio Galaxy
  • 2009
  • Ingår i: Science. - 0036-8075 .- 1095-9203. ; 325:5939, s. 444-448
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>The accretion of matter onto a massive black hole is believed to feed the relativistic plasma jets found in many active galactic nuclei (AGN). Although some AGN accelerate particles to energies exceeding 10(12) electron volts and are bright sources of very-high-energy (VHE) gamma-ray emission, it is not yet known where the VHE emission originates. Here we report on radio and VHE observations of the radio galaxy Messier 87, revealing a period of extremely strong VHE gamma-ray flares accompanied by a strong increase of the radio flux from its nucleus. These results imply that charged particles are accelerated to very high energies in the immediate vicinity of the black hole.</p>
  •  
2.
  • Abramowski, A., et al. (författare)
  • Simultaneous multi-wavelength campaign on PKS 2005-489 in a high state
  • 2011
  • Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 533, s. A110
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>The high-frequency peaked BL Lac object PKS 2005-489 was the target of a multi-wavelength campaign with simultaneous observations in the TeV gamma-ray (H.E.S.S.), GeV gamma-ray (Fermi/LAT), X-ray (RXTE, Swift), UV (Swift) and optical (ATOM, Swift) bands. This campaign was carried out during a high flux state in the synchrotron regime. The flux in the optical and X-ray bands reached the level of the historical maxima. The hard GeV spectrum observed with Fermi/LAT connects well to the very high energy (VHE, E &gt; 100 GeV) spectrum measured with H.E.S.S. with a peak energy between similar to 5 and 500 GeV. Compared to observations with contemporaneous coverage in the VHE and X-ray bands in 2004, the X-ray flux was similar to 50 times higher during the 2009 campaign while the TeV gamma-ray flux shows marginal variation over the years. The spectral energy distribution during this multi-wavelength campaign was fit by a one zone synchrotron self-Compton model with a well determined cutoff in X-rays. The parameters of a one zone SSC model are inconsistent with variability time scales. The variability behaviour over years with the large changes in synchrotron emission and small changes in the inverse Compton emission does not warrant an interpretation within a one-zone SSC model despite an apparently satisfying fit to the broadband data in 2009.</p>
  •  
3.
  • Acharya, B. S., et al. (författare)
  • Introducing the CTA concept
  • 2013
  • Ingår i: Astroparticle physics. - 0927-6505 .- 1873-2852. ; 43, s. 3-18
  • Tidskriftsartikel (övrigt vetenskapligt)abstract
    • <p>The Cherenkov Telescope Array (CTA) is a new observatory for very high-energy (VHE) gamma rays. CTA has ambitions science goals, for which it is necessary to achieve full-sky coverage, to improve the sensitivity by about an order of magnitude, to span about four decades of energy, from a few tens of GeV to above 100 TeV with enhanced angular and energy resolutions over existing VHE gamma-ray observatories. An international collaboration has formed with more than 1000 members from 27 countries in Europe, Asia, Africa and North and South America. In 2010 the CTA Consortium completed a Design Study and started a three-year Preparatory Phase which leads to production readiness of CTA in 2014. In this paper we introduce the science goals and the concept of CTA, and provide an overview of the project. (C) 2013 Elsevier B.V. All rights reserved.</p>
  •  
4.
  • Acharya, B. S., et al. (författare)
  • Introducing the CTA concept
  • 2013
  • Ingår i: Astroparticle Physics. - Elsevier. - 1873-2852. ; 43, s. 3-18
  • Tidskriftsartikel (övrigt vetenskapligt)abstract
    • The Cherenkov Telescope Array (CTA) is a new observatory for very high-energy (VHE) gamma rays. CTA has ambitions science goals, for which it is necessary to achieve full-sky coverage, to improve the sensitivity by about an order of magnitude, to span about four decades of energy, from a few tens of GeV to above 100 TeV with enhanced angular and energy resolutions over existing VHE gamma-ray observatories. An international collaboration has formed with more than 1000 members from 27 countries in Europe, Asia, Africa and North and South America. In 2010 the CTA Consortium completed a Design Study and started a three-year Preparatory Phase which leads to production readiness of CTA in 2014. In this paper we introduce the science goals and the concept of CTA, and provide an overview of the project. (C) 2013 Elsevier B.V. All rights reserved.
  •  
5.
  • Actis, M., et al. (författare)
  • Design concepts for the Cherenkov Telescope Array CTA : an advanced facility for ground-based high-energy gamma-ray astronomy
  • 2011
  • Ingår i: Experimental astronomy (Print). - Springer. - 0922-6435 .- 1572-9508. ; 32:3, s. 193-316
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.</p>
  •  
6.
  • Actis, M., et al. (författare)
  • Design concepts for the Cherenkov Telescope Array CTA : an advanced facility for ground-based high-energy gamma-ray astronomy
  • 2011
  • Ingår i: Experimental astronomy (Print). - 0922-6435 .- 1572-9508. ; 32:3, s. 193-316
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.</p>
  •  
7.
  • Actis, M., et al. (författare)
  • Design concepts for the Cherenkov Telescope Array CTA: an advanced facility for ground-based high-energy gamma-ray astronomy
  • 2011
  • Ingår i: Experimental Astronomy. - Springer. - 0922-6435. ; 32:3, s. 193-316
  • Tidskriftsartikel (refereegranskat)abstract
    • Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.
8.
  • Aartsen, M. G., et al. (författare)
  • Very high-energy gamma-ray follow-up program using neutrino triggers from IceCube
  • 2016
  • Ingår i: Journal of Instrumentation. - 1748-0221 .- 1748-0221. ; 11
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>We describe and report the status of a neutrino-triggered program in IceCube that generates real-time alerts for gamma-ray follow-up observations by atmospheric-Cherenkov telescopes (MAGIC and VERITAS). While IceCube is capable of monitoring the whole sky continuously, high-energy gamma-ray telescopes have restricted fields of view and in general are unlikely to be observing a potential neutrino-flaring source at the time such neutrinos are recorded. The use of neutrino-triggered alerts thus aims at increasing the availability of simultaneous multi-messenger data during potential neutrino flaring activity, which can increase the discovery potential and constrain the phenomenological interpretation of the high-energy emission of selected source classes (e. g. blazars). The requirements of a fast and stable online analysis of potential neutrino signals and its operation are presented, along with first results of the program operating between 14 March 2012 and 31 December 2015.</p>
  •  
9.
  • Menditto, Enrica, et al. (författare)
  • Adherence to treatment in allergic rhinitis using mobile technology : The MASK Study
  • 2019
  • Ingår i: Clinical and Experimental Allergy. - WILEY. - 0954-7894 .- 1365-2222. ; 49:4, s. 442-460
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Background: Mobile technology may help to better understand the adherence to treatment. MASK-rhinitis (Mobile Airways Sentinel NetworK for allergic rhinitis) is a patient-centred ICT system. A mobile phone app (the Allergy Diary) central to MASK is available in 22 countries. Objectives: To assess the adherence to treatment in allergic rhinitis patients using the Allergy Diary App. Methods: An observational cross-sectional study was carried out on all users who filled in the Allergy Diary from 1 January 2016 to 1 August 2017. Secondary adherence was assessed by using the modified Medication Possession Ratio (MPR) and the Proportion of days covered (PDC) approach. Results: A total of 12143 users were registered. A total of 6949 users reported at least one VAS data recording. Among them, 1887 users reported &gt;= 7 VAS data. About 1195 subjects were included in the analysis of adherence. One hundred and thirty-six (11.28%) users were adherent (MPR &gt;= 70% and PDC &lt;= 1.25), 51 (4.23%) were partly adherent (MPR &gt;= 70% and PDC = 1.50) and 176 (14.60%) were switchers. On the other hand, 832 (69.05%) users were non-adherent to medications (MPR &lt;70%). Of those, the largest group was non-adherent to medications and the time interval was increased in 442 (36.68%) users. Conclusion and clinical relevance: Adherence to treatment is low. The relative efficacy of continuous vs on-demand treatment for allergic rhinitis symptoms is still a matter of debate. This study shows an approach for measuring retrospective adherence based on a mobile app. This also represents a novel approach for analysing medication-taking behaviour in a real-world setting.</p>
  •  
10.
  • Aharonian, F., et al. (författare)
  • SIMULTANEOUS OBSERVATIONS OF PKS 2155-304 WITH HESS, FERMI, RXTE, AND ATOM : SPECTRAL ENERGY DISTRIBUTIONS AND VARIABILITY IN A LOW STATE
  • 2009
  • Ingår i: Astrophysical Journal Letters. - 2041-8205. ; 696:2, s. L150-L155
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>We report on the first simultaneous observations that cover the optical, X-ray, and high-energy gamma-ray bands of the BL Lac object PKS 2155-304. The gamma-ray bands were observed for 11 days, between 2008 August 25 and 2008 September 6 (MJD 54704-54715), jointly with the Fermi Gamma-ray Space Telescope and the HESS atmospheric Cherenkov array, providing the first simultaneous MeV-TeV spectral energy distribution (SED) with the new generation of gamma-ray telescopes. The ATOM telescope and the RXTE and Swift observatories provided optical and X-ray coverage of the low-energy component over the same time period. The object was close to the lowest archival X-ray and very high energy (VHE; &gt; 100 GeV) state, whereas the optical flux was much higher. The light curves show relatively little (similar to 30%) variability overall when compared to past flaring episodes, but we find a clear optical/VHE correlation and evidence for a correlation of the X-rays with the high-energy spectral index. Contrary to previous observations in the flaring state, we do not find any correlation between the X-ray and VHE components. Although synchrotron self-Compton models are often invoked to explain the SEDs of BL Lac objects, the most common versions of these models are at odds with the correlated variability we find in the various bands for PKS 2155-304.</p>
  •  
Skapa referenser, mejla, bekava och länka
Åtkomst
fritt online (17)
Typ av publikation
tidskriftsartikel (205)
forskningsöversikt (11)
konferensbidrag (1)
Typ av innehåll
refereegranskat (210)
övrigt vetenskapligt (10)
Författare/redaktör
Bulik, T. (68)
Boisson, C., (68)
Brun, P., (68)
Fontaine, G., (68)
Glicenstein, J. F., (68)
de Almeida, U. Barre ... (67)
visa fler...
Aharonian, F., (67)
Bernloehr, K., (67)
Domainko, W., (67)
Dyks, J., (67)
Egberts, K., (67)
Giebels, B., (67)
Khelifi, B., (67)
de Naurois, M., (67)
Farnier, C. (67)
Deil, C., (66)
Foerster, A., (66)
Hofmann, W., (66)
Lohse, T., (66)
Dubus, G. (66)
Behera, B. (66)
Henri, G., (65)
Hermann, G., (65)
Hinton, J. A., (65)
Horns, D., (65)
Jacholkowska, A., (65)
Kosack, K., (65)
Lamanna, G., (65)
Dyrda, M. (65)
Djannati-Atai, A., (64)
Fiasson, A., (64)
Hauser, M. (64)
Wilhelmi, E. de Ona, (63)
Moderski, R., (63)
Moulin, E., (63)
Santangelo, A., (63)
Venter, C., (63)
Vincent, P., (63)
Kaufmann, S. (63)
Heinzelmann, G. (62)
Akhperjanian, A. G., (62)
Chaves, R. C. G., (62)
Degrange, B., (62)
Fuessling, M., (62)
Gallant, Y. A., (62)
Katarzynski, K., (62)
Khangulyan, D., (62)
Marandon, V., (62)
Marcowith, A., (62)
Niemiec, J., (62)
visa färre...
Lärosäte
Karolinska Institutet (70)
Linnéuniversitetet (43)
Uppsala universitet (26)
Stockholms universitet (24)
Göteborgs universitet (19)
Lunds universitet (17)
visa fler...
Kungliga Tekniska Högskolan (12)
Linköpings universitet (9)
Umeå universitet (6)
Chalmers tekniska högskola (4)
Mittuniversitetet (1)
RISE (1)
visa färre...
Språk
Engelska (212)
Odefinierat språk (5)
Forskningsämne (UKÄ/SCB)
Naturvetenskap (105)
Medicin och hälsovetenskap (43)
Lantbruksvetenskap (5)
Teknik (4)

År

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy