The high-frequency-peaked BL Lac (HBL) 1ES 0806+524 (z = 0.138) was discovered in very high energy (VHE) gamma-rays in 2008. Until now, the broad-band spectrum of lES 0806+524 has been only poorly characterized, in particular at high energies. We analysed multiwave-length observations from gamma-rays to radio performed from 2011 January to March, which were triggered by the high activity detected at optical frequencies. These observations constitute the most precise determination of the broad-band emission of ES 0806+524 to date. The stereoscopic Major Atmospheric Gamma-Ray Imaging Cherenkov (MAGIC) observations yielded a gamma-ray signal above 250 GeV of (3.7 +/- 0.7) per cent of the Crab Nebula flux with a statistical significance of 9.9a. The multiwavelength observations showed significant variability in essentially all energy bands, including a VHE gamma-ray flare that lasted less than one night, which provided unprecedented evidence for short-term variability in lES 0806+524. The spectrum of this flare is well described by a power law with a photon index of 2.97 +/- 0.29 between similar to 150 GeV and 1 TeV and an integral flux of (9.3 +/- 1.9) per cent of the Crab nebula flux above 250 GeV. The spectrum during the non-flaring VHE activity is compatible with the only available VHE observation performed in 2008 with VERITAS when the source was in a low optical state. The broad-band spectral energy distribution can be described with a one-zone synchrotron self-Compton model with parameters typical for HBLs, indicating that lES 0806+524 is not substantially different from the HBLs previously detected.
MAGIC detection of short-term variability of the high-peaked BL Lac object lES 0806+524 / Aleksic J; Ansoldi S; Antonelli LA; Antoranz P; Babic A; Bangale P; Barrio JA; Gonzalez JB; Bednarek W; Bernardini E; Biasuzzi B; Biland A; Blanch O; Bonnefoy S; Bonnoli G; Borracci F; Bretz T; Carmona E; Carosi A; Colin P; Colombo E; Contreras JL; Cortina J; Covino S; Da Vela P; Dazzi F; De Angelis A; De Caneva G; De Lotto B; Wilhelmi ED; Mendez CD; Di Pierro F; Prester DD; Dorner D; Doro M; Einecke S; Eisenacher D; Elsaesser D; Fernandez-Barral A; Fidalgo D; Fonseca MV; Font L; Frantzen K; Fruck C; Galindo D; Lopez RJG; Garczarczyk M; Terrats DG; Gaug M; Godinovic N; Munoz AG; Gozzini SR; Hadasch D; Hanabata Y; Hayashida M; Herrera J; Hose J; Hrupec D; Idec W; Kadenius V; Kellermann H; Knoetig ML; Kodani K; Konno Y; Krause J; Kubo H; Kushida J; La Barbera A; Lelas D; Lewandowska N; Lindfors E; Lombardi S; Longo F; Lopez M; Lopez-Coto R; Lopez-Oramas A; Lorenz E; Lozano I; Makariev M; Mallot K; Maneva G; Mannheim K; Maraschi L; Marcote B; Mariotti M; Martinez M; Mazin D; Menzel U; Miranda JM; Mirzoyan R; Moralejo A; Munar-Adrover P; Nakajima D; Neustroev V; Niedzwiecki A; Rosillo MN; Nilsson K; Nishijima K; Noda K; Orito R; Overkemping A; Paiano S; Palatiello M; Paneque D; Paoletti R; Paredes JM; Paredes-Fortuny X; Persic M; Poutanen J; Moroni PGP; Prandini E; Puljak I; Reinthal R; Rhode W; Ribo M; Rico J; Garcia JR; Saito T; Saito K; Satalecka K; Scalzotto V; Scapin V; Schultz C; Schweizer T; Shore SN; Sillanpaa A; Sitarek J; Snidaric I; Sobczynska D; Stamerra A; Steinbring T; Strzys M; Takalo L; Takami H; Tavecchio F; Temnikov P; Terzic T; Tescaro D; Teshima M; Thaele J; Toyama DFTT; Toyama T; Treves A; Vogler P; Will M; Zanin R; Berger K; Buson S; DAmmando F; Gasparrini D; Hovatta T; Max-Moerbeck W; Readhead A; Richards J. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - ISSN 0035-8711. - STAMPA. - 451:1(2015), pp. 739-750. [10.1093/mnras/stv895]
MAGIC detection of short-term variability of the high-peaked BL Lac object lES 0806+524
D'AMMANDO, FILIPPO;
2015
Abstract
The high-frequency-peaked BL Lac (HBL) 1ES 0806+524 (z = 0.138) was discovered in very high energy (VHE) gamma-rays in 2008. Until now, the broad-band spectrum of lES 0806+524 has been only poorly characterized, in particular at high energies. We analysed multiwave-length observations from gamma-rays to radio performed from 2011 January to March, which were triggered by the high activity detected at optical frequencies. These observations constitute the most precise determination of the broad-band emission of ES 0806+524 to date. The stereoscopic Major Atmospheric Gamma-Ray Imaging Cherenkov (MAGIC) observations yielded a gamma-ray signal above 250 GeV of (3.7 +/- 0.7) per cent of the Crab Nebula flux with a statistical significance of 9.9a. The multiwavelength observations showed significant variability in essentially all energy bands, including a VHE gamma-ray flare that lasted less than one night, which provided unprecedented evidence for short-term variability in lES 0806+524. The spectrum of this flare is well described by a power law with a photon index of 2.97 +/- 0.29 between similar to 150 GeV and 1 TeV and an integral flux of (9.3 +/- 1.9) per cent of the Crab nebula flux above 250 GeV. The spectrum during the non-flaring VHE activity is compatible with the only available VHE observation performed in 2008 with VERITAS when the source was in a low optical state. The broad-band spectral energy distribution can be described with a one-zone synchrotron self-Compton model with parameters typical for HBLs, indicating that lES 0806+524 is not substantially different from the HBLs previously detected.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
