Radio Imaging of the Very-High-Energy γ-Ray Emission Region in the Central Engine of a Radio Galaxy

Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645, USA.
Science (Impact Factor: 31.48). 08/2009; 325(5939):444-8. DOI: 10.1126/science.1175406
Source: PubMed

ABSTRACT 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.

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Available from: I. Oya, Jul 26, 2014
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    • "Variability is also seen in objects where jets are not closely aligned with the line-of-sight to the observer, with the day-timescale TeV variability of M 87 (Aharonian et al. 2006) as the best studied case. Simultaneous VLBI and TeV observations of M 87 indicate a strong increase in flux from the nucleus during VHE flares (Acciari et al. 2009), suggesting particle acceleration is taking place very close to the central supermassive black hole. "
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    • "Theories involving particle acceleration in the jet usually place the emission region between 30 and a few thousand R Sch from the black hole, with R Sch the Schwarzschild radius (R Sch = 3×10 14 cm for a 10 9 M ¤ black hole). The observations of exceptionally strong γ-ray flares from M87 in 2008 observed by H.E.S.S., MAGIC and VERITAS in temporal coincidence with an exceptionally strong VLBA radio flare from the M87 radio core were interpreted as evidence for an origin of the γray flares within a projected distance of 50 R Sch from the central engine [31]. Unfortunately, a similar γ-flare in 2011 was not accompanied by a comparable radio flare and did not corroborate the association. "
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    • "– 4 – M87 Cen A black hole mass m = M/M ⊙ (3.2 ± 0.9) · 10 9 (1) , (6.4 ± 0.5) · 10 9 (2) (4.5 +1.7 −1.0 ) · 10 7 , (5.5 ± 3.0) · 10 7 (3) Gravitational radius R G 4.72 · 10 14 cm= 1.53 · 10 −4 pc ( * ) , 7.375 · 10 12 cm = 2.390 · 10 −6 pc 9.44 · 10 14 cm= 3.06 · 10 −4 pc ( * * ) distance from Earth d (16.7 ± 0.2) Mpc (4) (3.8 ± 0.1) Mpc (5) inclination i ( 15 − 25) • (6) , ( 30 − 35) • (7) , ( 15 − 80) • (9) , ( 30 − 45) • (8) ( 50 − 80) • (10) (pc-scale) nuclear X-ray luminosity L X 7.0 · 10 40 erg·s −1 ((0.5 − 7)keV) (11) ∼ 5·10 41 erg·s −1 ((2−10)keV) (12) nuclear bolometric ∼ 10 42 erg s −1 (13) ∼ 10 43 erg s −1 (14) luminosity L bol ( * ) for m = 3.2 · 10 9 , ( * * ) for m = 6.4 · 10 9 , (1) Macchetto et al. (1997), (2) Gebhardt and Thomas (2009), (3) Neumayer et al. (2010), (4) Mei et al. (2007), (5) Harris et al. (2009) , (6) Acciari et al. (2009),(7) Bicknell and Begelman (1996), (8) Ly et al. (2007), (9) Aharonian et al. (2009) and references therein, (10)Tingay et al. (1998), (11) Di Matteo et al. (2003), (12)Evans et al. (2004), (13) Reynolds et al. (1996) , (14) Karovska et al. (2002) "
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