X-ray hiccups from Sagittarius A* observed by XMM-Newton: The second brightest flare and three moderate flares caught in half a day

D. Porquet, N. Grosso, P. Predehl, G. Hasinger, F. Yusef-Zadeh, B. Aschenbach, G. Trap, Fulvio Melia, R. S. Warwick, A. Goldwurm, G. Bélanger, Y. Tanaka, R. Genzel, K. Dodds-Eden, M. Sakano, P. Ferrando

Research output: Contribution to journalArticle

103 Citations (Scopus)

Abstract

Context. Our Galaxy hosts at its dynamical center SgrA*, the closest supermassive black hole. Surprisingly, its luminosity is several orders of magnitude lower than the Eddington luminosity. However, the recent observations of occasional rapid X-ray flares from SgrA* provide constraints on the accretion and radiation mechanisms at work close to its event horizon.Aims. Our aim is to investigate the flaring activity of SgrA* and to constrain the physical properties of the X-ray flares.Methods. In Spring 2007, we observed SgrA* with XMM-Newton with a total exposure of ~230 ks. We have performed timing and spectral analysis of the new X-ray flares detected during this campaign. To study the range of flare spectral properties, in a consistent manner, we have also reprocessed, using the same analysis procedure and the latest calibration, archived XMM-Newton data of previously reported rapid flares. The dust scattering was taken into account during the spectral fitting. We also used Chandra archived observations of the quiescent state of SgrA* for comparison.Results. On April 4, 2007, we observed for the first time within a time interval of roughly half a day, an enhanced incidence rate of X-ray flaring, with a bright flare followed by three flares of more moderate amplitude. The former event represents the second brightest X-ray flare from Sgr A* on record with a peak amplitude of about 100 above the quiescent luminosity. This new bright flare exhibits similar light-curve shape (nearly symmetrical), duration (~3 ks) and spectral characteristics to the very bright flare observed in October 3, 2002 by XMM-Newton. The measured spectral parameters of the new bright flare, assuming an absorbed power law model taken into account dust scattering effect, are = cm and = 2.3 0.3 calculated at the 90% confidence level. The spectral parameter fits of the sum of the three following moderate flares, while lower ( = cm and ), are compatible within the error bars with those of the bright flares. The column density found, for a power-law model taking into account the dust scattering, during the flares is at least two times higher than the value expected from the (dust) visual extinction toward SgrA* ( ~ 25 mag), i.e., 4.5 10 cm. However, our fitting of the SgrA* quiescent spectra obtained with Chandra, for a power-law model taking into account the dust scattering, shows that an excess of column density is already present during the non-flaring phase.Conclusions. The two brightest X-ray flares observed so far from SgrA* exhibited similar soft spectra.

Original languageEnglish (US)
Pages (from-to)549-557
Number of pages9
JournalAstronomy and Astrophysics
Volume488
Issue number2
DOIs
StatePublished - Sep 2008

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XMM-Newton telescope
newton
flares
dust
scattering
power law
x rays
spectral analysis
luminosity
physical property
extinction
accretion
calibration
event horizon
light curve
spectrum analysis
confidence

Keywords

  • Galaxy: center
  • Radiation mechanisms: general
  • X-rays: general
  • X-rays: individuals: SgrA

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

X-ray hiccups from Sagittarius A* observed by XMM-Newton : The second brightest flare and three moderate flares caught in half a day. / Porquet, D.; Grosso, N.; Predehl, P.; Hasinger, G.; Yusef-Zadeh, F.; Aschenbach, B.; Trap, G.; Melia, Fulvio; Warwick, R. S.; Goldwurm, A.; Bélanger, G.; Tanaka, Y.; Genzel, R.; Dodds-Eden, K.; Sakano, M.; Ferrando, P.

In: Astronomy and Astrophysics, Vol. 488, No. 2, 09.2008, p. 549-557.

Research output: Contribution to journalArticle

Porquet, D, Grosso, N, Predehl, P, Hasinger, G, Yusef-Zadeh, F, Aschenbach, B, Trap, G, Melia, F, Warwick, RS, Goldwurm, A, Bélanger, G, Tanaka, Y, Genzel, R, Dodds-Eden, K, Sakano, M & Ferrando, P 2008, 'X-ray hiccups from Sagittarius A* observed by XMM-Newton: The second brightest flare and three moderate flares caught in half a day', Astronomy and Astrophysics, vol. 488, no. 2, pp. 549-557. https://doi.org/10.1051/0004-6361:200809986
Porquet, D. ; Grosso, N. ; Predehl, P. ; Hasinger, G. ; Yusef-Zadeh, F. ; Aschenbach, B. ; Trap, G. ; Melia, Fulvio ; Warwick, R. S. ; Goldwurm, A. ; Bélanger, G. ; Tanaka, Y. ; Genzel, R. ; Dodds-Eden, K. ; Sakano, M. ; Ferrando, P. / X-ray hiccups from Sagittarius A* observed by XMM-Newton : The second brightest flare and three moderate flares caught in half a day. In: Astronomy and Astrophysics. 2008 ; Vol. 488, No. 2. pp. 549-557.
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abstract = "Context. Our Galaxy hosts at its dynamical center SgrA*, the closest supermassive black hole. Surprisingly, its luminosity is several orders of magnitude lower than the Eddington luminosity. However, the recent observations of occasional rapid X-ray flares from SgrA* provide constraints on the accretion and radiation mechanisms at work close to its event horizon.Aims. Our aim is to investigate the flaring activity of SgrA* and to constrain the physical properties of the X-ray flares.Methods. In Spring 2007, we observed SgrA* with XMM-Newton with a total exposure of ~230 ks. We have performed timing and spectral analysis of the new X-ray flares detected during this campaign. To study the range of flare spectral properties, in a consistent manner, we have also reprocessed, using the same analysis procedure and the latest calibration, archived XMM-Newton data of previously reported rapid flares. The dust scattering was taken into account during the spectral fitting. We also used Chandra archived observations of the quiescent state of SgrA* for comparison.Results. On April 4, 2007, we observed for the first time within a time interval of roughly half a day, an enhanced incidence rate of X-ray flaring, with a bright flare followed by three flares of more moderate amplitude. The former event represents the second brightest X-ray flare from Sgr A* on record with a peak amplitude of about 100 above the quiescent luminosity. This new bright flare exhibits similar light-curve shape (nearly symmetrical), duration (~3 ks) and spectral characteristics to the very bright flare observed in October 3, 2002 by XMM-Newton. The measured spectral parameters of the new bright flare, assuming an absorbed power law model taken into account dust scattering effect, are = cm and = 2.3 0.3 calculated at the 90{\%} confidence level. The spectral parameter fits of the sum of the three following moderate flares, while lower ( = cm and ), are compatible within the error bars with those of the bright flares. The column density found, for a power-law model taking into account the dust scattering, during the flares is at least two times higher than the value expected from the (dust) visual extinction toward SgrA* ( ~ 25 mag), i.e., 4.5 10 cm. However, our fitting of the SgrA* quiescent spectra obtained with Chandra, for a power-law model taking into account the dust scattering, shows that an excess of column density is already present during the non-flaring phase.Conclusions. The two brightest X-ray flares observed so far from SgrA* exhibited similar soft spectra.",
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TY - JOUR

T1 - X-ray hiccups from Sagittarius A* observed by XMM-Newton

T2 - The second brightest flare and three moderate flares caught in half a day

AU - Porquet, D.

AU - Grosso, N.

AU - Predehl, P.

AU - Hasinger, G.

AU - Yusef-Zadeh, F.

AU - Aschenbach, B.

AU - Trap, G.

AU - Melia, Fulvio

AU - Warwick, R. S.

AU - Goldwurm, A.

AU - Bélanger, G.

AU - Tanaka, Y.

AU - Genzel, R.

AU - Dodds-Eden, K.

AU - Sakano, M.

AU - Ferrando, P.

PY - 2008/9

Y1 - 2008/9

N2 - Context. Our Galaxy hosts at its dynamical center SgrA*, the closest supermassive black hole. Surprisingly, its luminosity is several orders of magnitude lower than the Eddington luminosity. However, the recent observations of occasional rapid X-ray flares from SgrA* provide constraints on the accretion and radiation mechanisms at work close to its event horizon.Aims. Our aim is to investigate the flaring activity of SgrA* and to constrain the physical properties of the X-ray flares.Methods. In Spring 2007, we observed SgrA* with XMM-Newton with a total exposure of ~230 ks. We have performed timing and spectral analysis of the new X-ray flares detected during this campaign. To study the range of flare spectral properties, in a consistent manner, we have also reprocessed, using the same analysis procedure and the latest calibration, archived XMM-Newton data of previously reported rapid flares. The dust scattering was taken into account during the spectral fitting. We also used Chandra archived observations of the quiescent state of SgrA* for comparison.Results. On April 4, 2007, we observed for the first time within a time interval of roughly half a day, an enhanced incidence rate of X-ray flaring, with a bright flare followed by three flares of more moderate amplitude. The former event represents the second brightest X-ray flare from Sgr A* on record with a peak amplitude of about 100 above the quiescent luminosity. This new bright flare exhibits similar light-curve shape (nearly symmetrical), duration (~3 ks) and spectral characteristics to the very bright flare observed in October 3, 2002 by XMM-Newton. The measured spectral parameters of the new bright flare, assuming an absorbed power law model taken into account dust scattering effect, are = cm and = 2.3 0.3 calculated at the 90% confidence level. The spectral parameter fits of the sum of the three following moderate flares, while lower ( = cm and ), are compatible within the error bars with those of the bright flares. The column density found, for a power-law model taking into account the dust scattering, during the flares is at least two times higher than the value expected from the (dust) visual extinction toward SgrA* ( ~ 25 mag), i.e., 4.5 10 cm. However, our fitting of the SgrA* quiescent spectra obtained with Chandra, for a power-law model taking into account the dust scattering, shows that an excess of column density is already present during the non-flaring phase.Conclusions. The two brightest X-ray flares observed so far from SgrA* exhibited similar soft spectra.

AB - Context. Our Galaxy hosts at its dynamical center SgrA*, the closest supermassive black hole. Surprisingly, its luminosity is several orders of magnitude lower than the Eddington luminosity. However, the recent observations of occasional rapid X-ray flares from SgrA* provide constraints on the accretion and radiation mechanisms at work close to its event horizon.Aims. Our aim is to investigate the flaring activity of SgrA* and to constrain the physical properties of the X-ray flares.Methods. In Spring 2007, we observed SgrA* with XMM-Newton with a total exposure of ~230 ks. We have performed timing and spectral analysis of the new X-ray flares detected during this campaign. To study the range of flare spectral properties, in a consistent manner, we have also reprocessed, using the same analysis procedure and the latest calibration, archived XMM-Newton data of previously reported rapid flares. The dust scattering was taken into account during the spectral fitting. We also used Chandra archived observations of the quiescent state of SgrA* for comparison.Results. On April 4, 2007, we observed for the first time within a time interval of roughly half a day, an enhanced incidence rate of X-ray flaring, with a bright flare followed by three flares of more moderate amplitude. The former event represents the second brightest X-ray flare from Sgr A* on record with a peak amplitude of about 100 above the quiescent luminosity. This new bright flare exhibits similar light-curve shape (nearly symmetrical), duration (~3 ks) and spectral characteristics to the very bright flare observed in October 3, 2002 by XMM-Newton. The measured spectral parameters of the new bright flare, assuming an absorbed power law model taken into account dust scattering effect, are = cm and = 2.3 0.3 calculated at the 90% confidence level. The spectral parameter fits of the sum of the three following moderate flares, while lower ( = cm and ), are compatible within the error bars with those of the bright flares. The column density found, for a power-law model taking into account the dust scattering, during the flares is at least two times higher than the value expected from the (dust) visual extinction toward SgrA* ( ~ 25 mag), i.e., 4.5 10 cm. However, our fitting of the SgrA* quiescent spectra obtained with Chandra, for a power-law model taking into account the dust scattering, shows that an excess of column density is already present during the non-flaring phase.Conclusions. The two brightest X-ray flares observed so far from SgrA* exhibited similar soft spectra.

KW - Galaxy: center

KW - Radiation mechanisms: general

KW - X-rays: general

KW - X-rays: individuals: SgrA

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