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Detection of the blazar S4 0954+65 at very-high-energy with the MAGIC telescopes during an exceptionally high optical state |
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| Author: | Ahnen, M. L.1; Ansoldi, S.2,3,4,5,6,7; Antonelli, L. A.8; |
| Organizations: |
1ETH, CH-8093 Zurich, Switzerland. 2Univ Udine, I-33100 Udine, Italy. 3INFN Trieste, I-33100 Udine, Italy.
4Univ Tokyo, Japanese MAGIC Consortium ICRR, Chiba 2778582, Japan.
5Kyoto Univ, Dept Phys, Kyoto 6068502, Japan. 6Tokai Univ, Hiratsuka, Kanagawa 2591292, Japan. 7Univ Tokushima, Tokushima 7708502, Japan. 8Natl Inst Astrophys INAF, I-00136 Rome, Italy. 9Univ Padua, I-35131 Padua, Italy. 10Ist Nazl Fis Nucl, I-35131 Padua, Italy. 11Tech Univ Dortmund, D-44221 Dortmund, Germany. 12Univ Rijeka, Croatian MAGIC Consortium, Rijeka 51000, Croatia. 13Univ Split, FESB, Split, Croatia. 14Univ Zagreb, FER, Zagreb 10000, Croatia. 15Univ Osijek, Osijek 31000, Croatia. 16Rudjer Boskovic Inst, Zagreb 10000, Croatia. 17Saha Inst Nucl Phys, HBNI, 1-AF Bidhannagar,Sect 1, Kolkata 700064, India. 18Max Planck Inst Phys & Astrophys, D-80805 Munich, Germany. 19URCA, CBPF, BR-22290180 Rio De Janeiro, RJ, Brazil. 20Univ Complutense, Unidad Particulas & Cosmol UPARCOS, Madrid 28040, Spain. 21Univ Lodz, Dept Astrophys, PL-90236 Lodz, Poland. 22DESY, D-15738 Zeuthen, Germany. 23Humboldt Univ, Inst Phys, D-12489 Berlin, Germany. 24Univ Pisa, I-56126 Pisa, Italy. 25Ist Nazl Fis Nucl, I-56126 Pisa, Italy. 26Barcelona Inst Sci & Technol, IFAE, Bellaterra 08193, Barcelona, Spain. 27Univ Siena, I-53100 Siena, Italy. 28INFN Pisa, I-53100 Pisa, Italy. 29Inst Astrofis Canarias, E-38200 San Cristobal la Laguna, Spain. 30Univ La Laguna, Dept Astrofis, E-38206 Tenerife, Spain. 31PIC, Bellaterra 08193, Barcelona, Spain. 32Univ Wurzburg, D-97074 Wurzburg, Germany. 33Univ Turku, Tuorla Observ & Finnish, Ctr Astron, ESO FINCA,Finnish MAGIC Consortium, Vaisalantie 20, Piikkio 21500, Finland. 34Univ Oulu, Astron Div, Oulu 90014, Finland. 35Univ Autonoma Barcelona, Dept Fis, Bellaterra 08193, Spain. 36Univ Autonoma Barcelona, CERES IEEC, Bellaterra 08193, Spain. 37Univ Barcelona, ICC, IEEC UB, E-08028 Barcelona, Spain. 38Univ Trieste, Dipartimento Fis, I-34127 Trieste, Italy. 39Bulgarian Acad Sci, Inst Nucl Res & Nucl Energy, Sofia 1784, Bulgaria. 40Univ Bologna, INAF Trieste, Bologna, Italy. 41Univ Bologna, Dept Phys & Astron, Bologna, Italy. 42NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. 43Univ Maryland, Dept Phys, College Pk, MD 20742 USA. 44Univ Maryland, Dept Astron, College Pk, MD 20742 USA. 45Hiroshima Astrophys Sci Ctr, Hiroshima, Japan. 46Univ Maryland Baltimore Cty, Baltimore, MD 21228 USA. 47Catholic Univ Amer, Washington, DC USA. 48NRL, Div Space Sci, Washington, DC USA. 49Aalto Univ, Metsahovi Radio Observ, Espoo, Finland. 50Aalto Univ, Dept Elect & Nanoengn, Espoo, Finland. 51Tartu Observ, Tartu, Estonia. 52Univ Turku, Tuorla Observ, Vaisalantie 20, Piikkio 21500, Finland. 53St Petersburg State Univ, Astron Inst, St Petersburg, Russia. 54Boston Univ, Inst Astrophys Res, Boston, MA 02215 USA. 55Pulkovo Observ, St Petersburg, Russia. 56Crimean Astrophys Observ, PO Nauchny, UA-298409 Crimea, Ukraine. 57CSIC, Inst Astrofis Andalucia, Apartado 3004, Granada 18080, Spain. 58Max Planck Inst Radioastron, Hugel 69, D-53121 Bonn, Germany. 59Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. 60INAF, Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy. 61Univ La Laguna, Dept Astrofis, Tenerife 38205, Spain. |
| Format: | article |
| Version: | published version |
| Access: | open |
| Online Access: | PDF Full Text (PDF, 0.9 MB) |
| Persistent link: | http://urn.fi/urn:nbn:fi-fe2018101838443 |
| Language: | English |
| Published: |
EDP Sciences,
2018
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| Publish Date: | 2018-10-18 |
| Description: |
AbstractAims: The very high energy (VHE ≳100 GeV) γ-ray MAGIC observations of the blazar S4 0954+65, were triggered by an exceptionally high flux state of emission in the optical. This blazar has a disputed redshift of z = 0.368 or z ≥ 0.45 and an uncertain classification among blazar subclasses. The exceptional source state described here makes for an excellent opportunity to understand physical processes in the jet of S4 0954+65 and thus contribute to its classification. Methods: We investigated the multiwavelength (MWL) light curve and spectral energy distribution (SED) of the S4 0954+65 blazar during an enhanced state in February 2015 and have put it in context with possible emission scenarios. We collected photometric data in radio, optical, X-ray, and γ-ray. We studied both the optical polarization and the inner parsec-scale jet behavior with 43 GHz data. Results: Observations with the MAGIC telescopes led to the first detection of S4 0954+65 at VHE. Simultaneous data with Fermi-LAT at high energy γ-ray (HE, 100 MeV < E < 100 GeV) also show a period of increased activity. Imaging at 43 GHz reveals the emergence of a new feature in the radio jet in coincidence with the VHE flare. Simultaneous monitoring of the optical polarization angle reveals a rotation of approximately 100°. Conclusions: The high emission state during the flare allows us to compile the simultaneous broadband SED and to characterize it in the scope of blazar jet emission models. The broadband spectrum can be modeled with an emission mechanism commonly invoked for flat spectrum radio quasars (FSRQs), that is, inverse Compton scattering on an external soft photon fieldfrom the dust torus, also known as external Compton. The light curve and SED phenomenology is consistent with an interpretation of a blob propagating through a helical structured magnetic field and eventually crossing a standing shock in the jet, a scenario typically applied to FSRQs and low-frequency peaked BL Lac objects (LBL). see all
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| Series: |
Astronomy and astrophysics |
| ISSN: | 0004-6361 |
| ISSN-E: | 1432-0746 |
| ISSN-L: | 0004-6361 |
| Volume: | 617 |
| Article number: | A30 |
| DOI: | 10.1051/0004-6361/201832624 |
| OADOI: | https://oadoi.org/10.1051/0004-6361/201832624 |
| Type of Publication: |
A1 Journal article – refereed |
| Field of Science: |
115 Astronomy and space science |
| Subjects: | |
| Funding: |
The financial support of the German BMBF and MPG, the Italian INFN and INAF, the Swiss National Fund SNF, the ERDF under the Spanish MINECO (FPA2015-69818-P, FPA2012-36668, FPA2015-68378-P, FPA2015-69210-C6-2-R, FPA2015-69210-C6-4-R, FPA2015-69210-C6-6-R, AYA2015-71042-P, AYA2016-76012-C3-1-P, ESP2015-71662-C2-2-P, CSD2009-00064), and the Japanese JSPS and MEXT is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia “Severo Ochoa” SEV-2012-0234 and SEV-2015-0548, and Unidad de Excelencia “María de Maeztu” MDM-2014-0369, by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the Polish National Research Centre grant UMO-2016/22/M/ST9/00382 and by the Brazilian MCTIC, CNPq, and FAPERJ. The Fermi LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States, the Commissariat à l’Energie Atomique and the Centre National de la Recherche Scientifique/Institut National de Physique Nucléaire et de Physique des Particules in France, the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK), and Japan Aerospace Exploration Agency (JAXA) in Japan, and the K. A. Wallenberg Foundation, the Swedish Research Council and the Swedish National Space Board in Sweden. This work performed in part under DOE Contract DE-AC02-76SF00515. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Part of this work is based on archival data, software, or online services provided by the Space Science Data Center - ASI. The OVRO 40-m monitoring program is supported in part by NASA grants NNX08AW31G, NNX11A043G, and NNX14AQ89G, and NSF grants AST-0808050 and AST-1109911 The research at Boston University was supported by NASA Fermi Guest Investigator program grant 80NSSC17K0694 and US National Science Foundation grant AST-1615796. The VLBA is an instrument of the Long Baseline Observatory. The Long Baseline Observatory is a facility of the National Science Foundation operated by Associated Universities, Inc. This paper is partly based on observations carried out with the IRAM 30 m Telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). IA acknowledges support by a Ramón y Cajal grant of the Ministerio de Economía, Industria y Competitividad (MINECO) of Spain. The research at the IAA–CSIC was supported in part by the MINECO through grants AYA2016–80889–P, AYA2013–40825–P, and AYA2010–14844, and by the regional government of Andalucía through grant P09–FQM–4784. St. Petersburg University team acknowledges support from Russian Science Foundation grant 17-12-01029. The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics and is funded by the Smithsonian Institution and the Academia Sinica. |
| Copyright information: |
© ESO 2018. Published in this repository with the kind permission of the publisher. |