Stochastic Particle Acceleration and the Spacetime in Sgr A

1
Stochastic Particle Acceleration and the
Space-time in Sgr A

• Siming Liu
• Los Alamos National Laboratory, T-6
• Jon Bittner (Yale), Vahé Petrosian (Stanford),
  Fulvio Melia (U of A), Chris Fryer (LANL)
• Santa Fe, July 13 2006

2
Outline
Energetics in Black Hole Accretion Observations
of Sgr A Electron Acceleration During the NIR
and X-ray Flares
3
Energy Equation in Black Hole Accretion
Accretion Space-time
Gravitational Energy Black Hole Spin Energy
Internal Energy Radiation Outflow gt Internal
Energy
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Observation of Sagittarius A
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Sgr A A Compact Radio Source
Zhao et al. 1991, Nature, 354, 46
2 cm radio image of the central two light year
region (20)
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There is a Black Hole in Sgr A
Ghez et al. 2002
3-4 million Solar Mass
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X-Ray Flares From Sgr A
Quasi-periodic Modulation
Belanger et al. 2005
Baganoff et al. 2001
Porquet et al. 2003
8
NIR Flares From Sgr A
Quasi-periodic Modulation
Genzel et al. 2003
9
Sgr A 19-20 June 2003 NIR/X-ray Flare
Eckart et al. (2004)
Baganoff 2005
Lx 6x1033 erg s-1 Lnir 5x1034 erg s-1
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Correlation between NIR Flux and Spectral Index
Krabbe et al. 2006
Gillesen et al. 2006
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Broadband Spectrum
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Emission Processes During Flares
Thermal Synchrotron and SSC Four Parameters B,
kBT ?crmec2, N , AR2
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Emission Processes During Flares
Liu et al. 2006
14
Stochastic Electron Acceleration During the NIR
and X-ray Flares
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Stochastic Electron Acceleration
Liu et al. 2006
16
Electron Acceleration During Flares
Bittner et al. 2006
17
Electron Acceleration During Flares
Bittner et al. 2006
18
Thermal Synchrotron
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Thermal Synchrotron and SSC
20
Emission Processes During Flares
Liu et al. 2006
21
Steady-State
Liu et al. 2006
22
Example
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Example
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Conclusion

• With simultaneous NIR and X-ray spectroscopy,
  one can measure the internal energy of electrons
  near the black hole in Sagittarius A and
  constrain the black hole spin.