Fast Variability of TeraElectron Volt γ Rays from the Radio Galaxy M87

Aharonian, F.; Akhperjanian, A. G.; Bazer‐Bachi, A. R.; Beilicke, M.; Benbow, W.; Berge, D.; Bernlöhr, K.; Boisson, C.; Bolz, O.; Borrel, V.; Braun, I.; Brown, A. M.; Bühler, R.; Büsching, I.; Carrigan, S.; Chadwick, P. M.; Chounet, L.‐M.; Coignet, G.; Cornils, R.; Costamante, L.; Degrange, B.; Dickinson, H. J.; Djannati‐Ataï, A.; Drury, L. O’c.; Dubus, G.; Egberts, K.; Emmanoulopoulos, D.; Espigat, P.; Feinstein, F.; Ferrero, E.; Fiaßon, A.; Fontaine, G.; Funk, Sebastian; Füßling, M.; Gallant, Y. A.; Giebels, B.; Glicenstein, J. F.; Goret, P.; Hadjichristidis, C.; Hauser, D.; Hauser, M.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hoffmann, A.; Hofmann, W.; Holleran, M.; Hoppe, S.; Horns, D.; Jachołkowska, A.; Jager, O. C. de; Kendziorra, E.; Kerschhaggl, M.; Khélifi, B.; Komin, Nu.; Konopelko, A.; Kosack, K.; Lamanna, G.; Latham, I. J.; Gallou, R. Le; Lemière, A.; Lemoine‐Goumard, M.; Lenain, J.‐P.; Löhse, T.; Martin, Jean‐Michel; Martineau‐Huynh, O.; Marcowith, A.; Masterson, C.; Maurin, Guillaume; McComb, T. J. L.; Moulin, Emmanuel; Naurois, M. de; Nedbal, D.; Nolan, S. J.; Noutsos, A.; Orford, K. J.; Osborne, J. L.; Ouchrif, M.; Panter, M.; Pelletier, G.; Pita, S.; Pühlhofer, G.; Punch, M.; Ranchon, S.; Raubenheimer, B. C.; Raue, M.; Rayner, S. M.; Reimer, A.; Ripken, J.; Rob, L.; Rolland, L.; Rosier‐Lees, S.; Rowell, G.; Sahakian, V.; Santangelo, A.; Saugé, L.; Schlenker, S.; Schlickeiser, R.; Schröder, R.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Shalchi, A.; Sol, H.; Spangler, D.; Spanier, F.; Steenkamp, R.; Stegmann, C.; Superina, G.; Tam, P. H. T.; Tavernet, J.‐P.; Terrier, R.; Tluczykont, M.; Eldik, C. van; Vasileiadis, G.; Venter, C.; Vialle, J. P.; Vincent, P.; Völk, H. J.; Wagner, S. J.; Ward, M. J.

doi:10.1126/science.1134408

Cited by 314 publications

(292 citation statements)

References 25 publications

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“…The first hint of very high energy (VHE; 1250 GeV) g-ray emission was reported by Aharonian et al (2003), and later confirmed by Aharonian et al (2006) and Acciari et al (2008). The emission is variable on a timescale of years.…”

Section: Introductionmentioning

confidence: 82%

Very High Energy Gamma-Ray Observations of Strong Flaring Activity in M87 in 2008 February

Albert

Aliu

Anderhub

et al. 2008

ApJ

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M87 is the only known nonblazar radio galaxy to emit very high energy (VHE) gamma rays. During a monitoring program of M87, a rapid flare in VHE gamma-rays was detected by the MAGIC telescope in early 2008. The flux was found to be variable above 350 GeV on a timescale as short as 1 day at a significance level of 5.6 j. The highest measured flux reached 15% of the Crab Nebula flux. We observed several substantial changes of the flux level during the 13 day observing period. The flux at lower energies (150-350 GeV), instead, is compatible with being constant. The energy spectrum can be described by a power law with a photon index of 2.30 ‫ע‬ 0.11 stat ‫ע‬ 0.20 syst . The observed day-scale flux variability at VHE prefers the M87 core as source of the emission and implies that either the emission region is very compact (just a few Schwarzschild radii) or the Doppler factor of the emitting blob is rather large in the case of a nonexpanding emission region.

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Section: Introductionmentioning

confidence: 82%

Very High Energy Gamma-Ray Observations of Strong Flaring Activity in M87 in 2008 February

Albert

Aliu

Anderhub

et al. 2008

ApJ

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“…as NGC 1275; z = 0.017559, belonging to the Perseus cluster as well, and also detected by Fermi/LAT). M87 in the Virgo Cluster shares many properties similar to IC 310, and here the emission could be traced to a blazar-like central engine (Aharonian et al 2006;Acciari et al 2009). Unification models of radio-loud active galactic nuclei predict low-luminosity FRI radio galaxies to be the parent population of BL Lacertae objects whose characteristics would only become dominant for small jet angles to the line-of-sight, although other effects (e.g., hidden emission line regions, adiabatic losses, mass entrainment, jet deceleration, spine-sheath structure) complicate the picture (Xu et al 2000).…”

Section: Introductionmentioning

confidence: 99%

The blazar-like radio structure of the TeV source IC 310

Kadler

Eisenacher

Ros

et al. 2012

A&A

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Context. The radio galaxy IC 310 in the Perseus cluster has recently been detected in the gamma-ray regime at GeV and TeV energies. The TeV emission shows time variability and an extraordinarily hard spectrum, even harder than the spectrum of the similar nearby gamma-ray emitting radio galaxy M 87. Aims. High-resolution studies of the radio morphology help to constrain the geometry of the jet on sub-pc scales and to find out where the high-energy emission might come from. Methods. We analyzed May 2011 VLBA data of IC 310 at a wavelength of 3.6 cm, revealing the parsec-scale radio structure of this source. We compared our findings with more information available from contemporary single-dish flux density measurements with the 100-m Effelsberg radio telescope. Results. We have detected a one-sided core-jet structure with blazar-like, beamed radio emission oriented along the same position angle as the kiloparsec scale radio structure observed in the past by connected interferometers. Doppler-boosting favoritism is consistent with an angle of θ < ∼ 38 • between the jet axis and the line-of-sight, i.e., very likely within the boundary dividing low-luminosity radio galaxies and BL Lac objects in unified schemes. Conclusions. The stability of the jet orientation from parsec to kiloparsec scales in IC 310 argues against its classification as a headtail radio galaxy; i.e., there is no indication of an interaction with the intracluster medium that would determine the direction of the tail. IC 310 seems to represent a low-luminosity FRI radio galaxy at a borderline angle to reveal its BL Lac-type central engine.

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“…However, the temporal variability of the H.E.S.S. signal [3] excludes the bulk of the signal in the TeV range to be of a dark matter origin. Prospects of indirect detection from the Andromeda galaxy M31 [4] and the Large Magellanic Cloud [5] have been also investigated.…”

Section: Introductionmentioning

confidence: 99%

Erratum to “Observations of the Sagittarius dwarf galaxy by the HESS experiment and search for a dark matter signal” [Astropart. Phys. 29(1) (2008) 55–62]

Aharonian¹,

Akhperjanian²,

Bazer‐Bachi³

et al. 2010

Astroparticle Physics

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Observations of the Sagittarius dwarf spheroidal (Sgr dSph) galaxy were carried out with the H.E.S.S. array of four imaging air Cherenkov telescopes in June 2006. A total of 11 hours of high quality data are available after data selection. There is no evidence for a very high energy γ-ray signal above the energy threshold at the target position. A 95% C.L. flux limit of 3.6 × 10 −12 cm −2 s −1 above 250 GeV has been derived. Constraints on the velocity-weighted cross section σv are calculated in the framework of Dark Matter particle annihilation using realistic models for the Dark Matter halo profile of Sagittarius dwarf galaxy. Two different models have been investigated encompassing a large class of halo types. A 95% C.L. exclusion limit on σv of the order of 2 × 10 −25 cm 3 s −1 is obtained for a core profile in the 100 GeV -1 TeV neutralino mass range.

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Fast Variability of TeraElectron Volt γ Rays from the Radio Galaxy M87

Cited by 314 publications

References 25 publications

Very High Energy Gamma-Ray Observations of Strong Flaring Activity in M87 in 2008 February

Very High Energy Gamma-Ray Observations of Strong Flaring Activity in M87 in 2008 February

The blazar-like radio structure of the TeV source IC 310

Erratum to “Observations of the Sagittarius dwarf galaxy by the HESS experiment and search for a dark matter signal” [Astropart. Phys. 29(1) (2008) 55–62]

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Fast Variability of TeraElectron Volt γ Rays from the Radio Galaxy M87

Cited by 314 publications

References 25 publications

Very High Energy Gamma-Ray Observations of Strong Flaring Activity in M87 in 2008 February

Very High Energy Gamma-Ray Observations of Strong Flaring Activity in M87 in 2008 February

The blazar-like radio structure of the TeV source IC 310

Erratum to “Observations of the Sagittarius dwarf galaxy by the HESS experiment and search for a dark matter signal” [Astropart. Phys. 29(1) (2008) 55–62]

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Fast Variability of TeraElectron Volt γ Rays from the Radio Galaxy M87