Modeling mm- to X-ray flare emission from sagittarius A

A. Eckart, F. K. Baganoff, M. R. Morris, D. Kunneriath, M. Zamaninasab, G. Witzel, R. Schödel, M. García-Marín, L. Meyer, G. C. Bower, Daniel P Marrone, M. W. Bautz, W. N. Brandt, G. P. Garmire, G. R. Ricker, C. Straubmeier, D. A. Roberts, K. Muzic, J. Mauerhan, A. Zensus

Research output: Contribution to journalArticle

44 Citations (Scopus)

Abstract

Context. We report on new modeling results based on the mm- to X-ray emission of the SgrA* counterpart associated with the massive ∼4×106 Mȯ black hole at the Galactic Center.Aims. We investigate the physical processes responsible for the variable emission from SgrA*. Methods. Our modeling is based on simultaneous observations carried out on 07 July, 2004, using the NACO adaptive optics (AO) instrument at the European Southern Observatory's Very Large Telescope*and the ACIS-I instrument aboard the Chandra X-ray Observatory as well as the Submillimeter Array SMA**on Mauna Kea, Hawaii, and the Very Large Array***in New Mexico. Results. The observations revealed several flare events in all wavelength domains. Here we show that the flare emission can be described with a combination of a synchrotron self-Compton (SSC) model followed by an adiabatic expansion of the source components. The SSC emission at NIR and X-ray wavelengths involves up-scattered sub-millimeter photons from a compact source component. At the start of the flare, spectra of these components peak at frequencies between several 100 GHz and 2 THz. The adiabatic expansion then accounts for the variable emission observed at sub-mm/mm wavelengths. The derived physical quantities that describe the flare emission give a blob expansion speed of vexp ∼ 0.005 c, magnetic field of B around 60 G or less and spectral indices of α = 0.8 to 1.4, corresponding to a particle spectral index p ∼2.6 to 3.8. Conclusions. A combined SSC and adiabatic expansion model can fully account for the observed flare flux densities and delay times covering the spectral range from the X-ray to the mm-radio domain. The derived model parameters suggest that the adiabatic expansion takes place in source components that have a bulk motion larger than vexp or the expanding material contributes to a corona or disk, confined to the immediate surroundings of SgrA*.

Original languageEnglish (US)
Pages (from-to)935-946
Number of pages12
JournalAstronomy and Astrophysics
Volume500
Issue number3
DOIs
StatePublished - Jun 2009
Externally publishedYes

Fingerprint

flares
expansion
modeling
synchrotrons
x rays
wavelength
observatory
wavelengths
spectral mixture analysis
Very Large Array (VLA)
European Southern Observatory
adaptive optics
coronas
corona
observatories
coverings
time lag
flux density
telescopes
radio

Keywords

  • Accretion, accretion disks
  • Black hole physics
  • Galaxy: center
  • Galaxy: nucleus
  • Infrared: general
  • X-rays: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Eckart, A., Baganoff, F. K., Morris, M. R., Kunneriath, D., Zamaninasab, M., Witzel, G., ... Zensus, A. (2009). Modeling mm- to X-ray flare emission from sagittarius A. Astronomy and Astrophysics, 500(3), 935-946. https://doi.org/10.1051/0004-6361/200811354

Modeling mm- to X-ray flare emission from sagittarius A. / Eckart, A.; Baganoff, F. K.; Morris, M. R.; Kunneriath, D.; Zamaninasab, M.; Witzel, G.; Schödel, R.; García-Marín, M.; Meyer, L.; Bower, G. C.; Marrone, Daniel P; Bautz, M. W.; Brandt, W. N.; Garmire, G. P.; Ricker, G. R.; Straubmeier, C.; Roberts, D. A.; Muzic, K.; Mauerhan, J.; Zensus, A.

In: Astronomy and Astrophysics, Vol. 500, No. 3, 06.2009, p. 935-946.

Research output: Contribution to journalArticle

Eckart, A, Baganoff, FK, Morris, MR, Kunneriath, D, Zamaninasab, M, Witzel, G, Schödel, R, García-Marín, M, Meyer, L, Bower, GC, Marrone, DP, Bautz, MW, Brandt, WN, Garmire, GP, Ricker, GR, Straubmeier, C, Roberts, DA, Muzic, K, Mauerhan, J & Zensus, A 2009, 'Modeling mm- to X-ray flare emission from sagittarius A', Astronomy and Astrophysics, vol. 500, no. 3, pp. 935-946. https://doi.org/10.1051/0004-6361/200811354
Eckart A, Baganoff FK, Morris MR, Kunneriath D, Zamaninasab M, Witzel G et al. Modeling mm- to X-ray flare emission from sagittarius A. Astronomy and Astrophysics. 2009 Jun;500(3):935-946. https://doi.org/10.1051/0004-6361/200811354
Eckart, A. ; Baganoff, F. K. ; Morris, M. R. ; Kunneriath, D. ; Zamaninasab, M. ; Witzel, G. ; Schödel, R. ; García-Marín, M. ; Meyer, L. ; Bower, G. C. ; Marrone, Daniel P ; Bautz, M. W. ; Brandt, W. N. ; Garmire, G. P. ; Ricker, G. R. ; Straubmeier, C. ; Roberts, D. A. ; Muzic, K. ; Mauerhan, J. ; Zensus, A. / Modeling mm- to X-ray flare emission from sagittarius A. In: Astronomy and Astrophysics. 2009 ; Vol. 500, No. 3. pp. 935-946.
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abstract = "Context. We report on new modeling results based on the mm- to X-ray emission of the SgrA* counterpart associated with the massive ∼4×106 Mȯ black hole at the Galactic Center.Aims. We investigate the physical processes responsible for the variable emission from SgrA*. Methods. Our modeling is based on simultaneous observations carried out on 07 July, 2004, using the NACO adaptive optics (AO) instrument at the European Southern Observatory's Very Large Telescope*and the ACIS-I instrument aboard the Chandra X-ray Observatory as well as the Submillimeter Array SMA**on Mauna Kea, Hawaii, and the Very Large Array***in New Mexico. Results. The observations revealed several flare events in all wavelength domains. Here we show that the flare emission can be described with a combination of a synchrotron self-Compton (SSC) model followed by an adiabatic expansion of the source components. The SSC emission at NIR and X-ray wavelengths involves up-scattered sub-millimeter photons from a compact source component. At the start of the flare, spectra of these components peak at frequencies between several 100 GHz and 2 THz. The adiabatic expansion then accounts for the variable emission observed at sub-mm/mm wavelengths. The derived physical quantities that describe the flare emission give a blob expansion speed of vexp ∼ 0.005 c, magnetic field of B around 60 G or less and spectral indices of α = 0.8 to 1.4, corresponding to a particle spectral index p ∼2.6 to 3.8. Conclusions. A combined SSC and adiabatic expansion model can fully account for the observed flare flux densities and delay times covering the spectral range from the X-ray to the mm-radio domain. The derived model parameters suggest that the adiabatic expansion takes place in source components that have a bulk motion larger than vexp or the expanding material contributes to a corona or disk, confined to the immediate surroundings of SgrA*.",
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AU - Eckart, A.

AU - Baganoff, F. K.

AU - Morris, M. R.

AU - Kunneriath, D.

AU - Zamaninasab, M.

AU - Witzel, G.

AU - Schödel, R.

AU - García-Marín, M.

AU - Meyer, L.

AU - Bower, G. C.

AU - Marrone, Daniel P

AU - Bautz, M. W.

AU - Brandt, W. N.

AU - Garmire, G. P.

AU - Ricker, G. R.

AU - Straubmeier, C.

AU - Roberts, D. A.

AU - Muzic, K.

AU - Mauerhan, J.

AU - Zensus, A.

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N2 - Context. We report on new modeling results based on the mm- to X-ray emission of the SgrA* counterpart associated with the massive ∼4×106 Mȯ black hole at the Galactic Center.Aims. We investigate the physical processes responsible for the variable emission from SgrA*. Methods. Our modeling is based on simultaneous observations carried out on 07 July, 2004, using the NACO adaptive optics (AO) instrument at the European Southern Observatory's Very Large Telescope*and the ACIS-I instrument aboard the Chandra X-ray Observatory as well as the Submillimeter Array SMA**on Mauna Kea, Hawaii, and the Very Large Array***in New Mexico. Results. The observations revealed several flare events in all wavelength domains. Here we show that the flare emission can be described with a combination of a synchrotron self-Compton (SSC) model followed by an adiabatic expansion of the source components. The SSC emission at NIR and X-ray wavelengths involves up-scattered sub-millimeter photons from a compact source component. At the start of the flare, spectra of these components peak at frequencies between several 100 GHz and 2 THz. The adiabatic expansion then accounts for the variable emission observed at sub-mm/mm wavelengths. The derived physical quantities that describe the flare emission give a blob expansion speed of vexp ∼ 0.005 c, magnetic field of B around 60 G or less and spectral indices of α = 0.8 to 1.4, corresponding to a particle spectral index p ∼2.6 to 3.8. Conclusions. A combined SSC and adiabatic expansion model can fully account for the observed flare flux densities and delay times covering the spectral range from the X-ray to the mm-radio domain. The derived model parameters suggest that the adiabatic expansion takes place in source components that have a bulk motion larger than vexp or the expanding material contributes to a corona or disk, confined to the immediate surroundings of SgrA*.

AB - Context. We report on new modeling results based on the mm- to X-ray emission of the SgrA* counterpart associated with the massive ∼4×106 Mȯ black hole at the Galactic Center.Aims. We investigate the physical processes responsible for the variable emission from SgrA*. Methods. Our modeling is based on simultaneous observations carried out on 07 July, 2004, using the NACO adaptive optics (AO) instrument at the European Southern Observatory's Very Large Telescope*and the ACIS-I instrument aboard the Chandra X-ray Observatory as well as the Submillimeter Array SMA**on Mauna Kea, Hawaii, and the Very Large Array***in New Mexico. Results. The observations revealed several flare events in all wavelength domains. Here we show that the flare emission can be described with a combination of a synchrotron self-Compton (SSC) model followed by an adiabatic expansion of the source components. The SSC emission at NIR and X-ray wavelengths involves up-scattered sub-millimeter photons from a compact source component. At the start of the flare, spectra of these components peak at frequencies between several 100 GHz and 2 THz. The adiabatic expansion then accounts for the variable emission observed at sub-mm/mm wavelengths. The derived physical quantities that describe the flare emission give a blob expansion speed of vexp ∼ 0.005 c, magnetic field of B around 60 G or less and spectral indices of α = 0.8 to 1.4, corresponding to a particle spectral index p ∼2.6 to 3.8. Conclusions. A combined SSC and adiabatic expansion model can fully account for the observed flare flux densities and delay times covering the spectral range from the X-ray to the mm-radio domain. The derived model parameters suggest that the adiabatic expansion takes place in source components that have a bulk motion larger than vexp or the expanding material contributes to a corona or disk, confined to the immediate surroundings of SgrA*.

KW - Accretion, accretion disks

KW - Black hole physics

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KW - Galaxy: nucleus

KW - Infrared: general

KW - X-rays: general

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