EVIDENCE FOR X-RAY SYNCHROTRON EMISSION FROM SIMULTANEOUS MID-INFRARED TO X-RAY OBSERVATIONS OF A STRONG Sgr A* FLARE

Dodds-Eden, K.; Porquet, D.; Trap, G.; Quataert, Eliot; Haubois, X.; Gillessen, S.; Grosso, N.; Pantin, E.; Falcke, H.; Rouan, D.; Genzel, R.; Hasinger, G.; Goldwurm, A.; Yusef‐Zadeh, F.; Clénet, Y.; Trippe, Sascha; Lagage, P. O.; Bartko, H.; Eisenhauer, F.; Ott, T.; Paumard, T.; Perrin, G.; Yuan, Feng; Fritz, Tobias; Mascetti, L.

doi:10.1088/0004-637x/698/1/676

Cited by 171 publications

(378 citation statements)

References 62 publications

Supporting

Mentioning

351

Contrasting

Order By: Relevance

“…Hence, these models are consistent with the observed millimeter variability of SgrA*. However, since Dexter et al (2009Dexter et al ( , 2010) concentrate only on modeling the (sub-)millimeter emission, their modeling could not reproduce the observed NIR/X-ray flares and corresponding (sub-)millimeter flares (Eckart et al 2008;Marrone et al 2008;Dodds-Eden et al 2009;Yusef-Zadeh et al 2008, which are most likely physically associated. The authors also clearly state that -in the framework of their modeling -it is unclear how their description of variability is linked to the NIR/X-ray flare activity.…”

Section: Sub-mm Variability From a Magnetized Accretion Flowmentioning

confidence: 70%

“…All NIR flux densities taken from the literature were corrected to a value of A K = 2.46 (Schödel et al 2010). For the L -band flares reported by Dodds-Eden et al (2009;4 April 2007) and by Trap et al (2010;1 April 2009), we corrected the L -band flux densites to an extinction of A L = 1.23 (Schödel et al 2010) and extrapolated to the Ks-band assuming a spectral index of 0.7 ± 0.3 (Hornstein et al 2007; see also Bremer et al 2011). In this sample, we also included an X-ray flare that had not been detected simultaneously in the NIR (Marrone et al 2008).…”

Section: The Sample Of Simultaneous Nir/x-ray Flaresmentioning

confidence: 99%

“…They demonstrated that SSC models need a lower Lorenz factor of about 10 3 and a significantly larger percentage of accelerated particles. Dodds-Eden et al (2009) modeled a single, exceptionally bright X-ray flare event using a pure synchrotron description. This illustrates that the need to include as little as possible a SSC contribution to the predicted X-ray flux places stringent constraints on the pure synchrotron model (Dodds-Eden et al 2010).…”

Section: The Synchrotron Cutoff Frequency νmentioning

confidence: 99%

“…In general, the flare profiles are more complex. They are not necessarily symmetric with respect to the peak (see the first X-ray flare detection by Baganoff et al 2001) and significant differences between the NIR and X-ray flare profiles have been reported (e.g., Eckart et al 2006a;Marrone et al 2008;Yusef-Zadeh et al 2008;Sabha et al 2010;Dodds-Eden et al 2009.…”

Section: The Nir/x-ray Flare Profilesmentioning

confidence: 99%

See 3 more Smart Citations

Millimeter to X-ray flares from Sagittarius A*

Eckart

García-Marín

Vogel

et al. 2012

A&A

146

View full text Add to dashboard Cite

Context. We report on new simultaneous observations and modeling of the millimeter, near-infrared, and X-ray flare emission of the source Sagittarius A* (SgrA*) associated with the super-massive (4 × 10 6 M ) black hole at the Galactic center. Aims. We study the applicability of the adiabatic synchrotron source expansion model and study physical processes giving rise to the variable emission of SgrA* from the radio to the X-ray domain. Methods. Our observations were carried out on 18 May 2009 using the NACO adaptive optics (AO) instrument at the European Southern Observatory's Very Large Telescope, the ACIS-I instrument aboard the Chandra X-ray Observatory, the LABOCA bolometer at the Atacama Pathfinder EXperiment (APEX), and the CARMA mm telescope array at Cedar Flat, California. Results. The X-ray flare had an excess 2−8 keV luminosity between 6 and 12×10 33 erg s −1 . The observations reveal flaring activity in all wavelength bands that can be modeled as the signal from an adiabatically expanding synchrotron self-Compton (SSC) component.Modeling of the light curves shows that the sub-mm follows the NIR emission with a delay of about three-quarters of an hour with an expansion velocity of about v exp ∼ 0.009c. We find source component sizes of around one Schwarzschild radius, flux densities of a few Janskys, and spectral indices α of about +1 (S (ν) ∝ ν −α ). At the start of the flare, the spectra of the two main components peak just short of 1 THz. To statistically explain the observed variability of the (sub-)mm spectrum of SgrA*, we use a sample of simultaneous NIR/X-ray flare peaks and model the flares using a synchrotron and SSC mechanism. Conclusions. These parameters suggest that either the adiabatically expanding source components have a bulk motion larger than v exp or the expanding material contributes to a corona or disk, confined to the immediate surroundings of SgrA*. For the bulk of the synchrotron and SSC models, we find synchrotron turnover frequencies in the range of 300−400 GHz. For the pure synchrotron models, this results in densities of relativistic particles of the order of 10 6.5 cm −3 and for the SSC models, the median densities are about one order of magnitude higher. However, to obtain a realistic description of the frequency-dependent variability amplitude of SgrA*, models with higher turnover frequencies and even higher densities are required.

show abstract

Section: Sub-mm Variability From a Magnetized Accretion Flowmentioning

confidence: 70%

Section: The Sample Of Simultaneous Nir/x-ray Flaresmentioning

confidence: 99%

Section: The Synchrotron Cutoff Frequency νmentioning

confidence: 99%

Section: The Nir/x-ray Flare Profilesmentioning

confidence: 99%

See 2 more Smart Citations

Millimeter to X-ray flares from Sagittarius A*

Eckart

García-Marín

Vogel

et al. 2012

A&A

146

View full text Add to dashboard Cite

show abstract

“…Accelerated electrons of Lorentz factor γ ∼ 10 3 −10 6 are required to produce the NIR and X-ray emission via synchrotron emission and/or inverse A&A 540, A41 (2012) Compton scattering (Markoff et al 2001;Yuan et al 2003Yuan et al , 2004Dodds-Eden et al 2009;Eckart et al 2006b). The possible origins of the hot electrons include magnetic reconnection in the accretion flow (Baganoff et al 2001;Markoff et al 2001), stochastic acceleration (Liu et al 2006), fluctuations in the accretion rate, or even the tidal disruption of a small infalling body such as an asteroid (Čadež et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Flares and variability from Sagittarius A*: five nights of simultaneous multi-wavelength observations

Haubois¹,

Dodds-Eden²,

Weiß³

et al. 2012

A&A

Self Cite

View full text Add to dashboard Cite

Aims. We report on simultaneous observations and modeling of mid-infrared (MIR), near-infrared (NIR), and submillimeter (submm) emission of the source Sgr A* associated with the supermassive black hole at the center of our Galaxy. Our goal was to monitor the activity of Sgr A* at different wavelengths in order to constrain the emitting processes and gain insight into the nature of the close environment of Sgr A*. Methods. We used the MIR instrument VISIR in the BURST imaging mode, the adaptive optics assisted NIR camera NACO, and the sub-mm antenna APEX to monitor Sgr A* over several nights in July 2007. Results. The observations reveal remarkable variability in the NIR and sub-mm during the five nights of observation. No source was detected in the MIR, but we derived the lowest upper limit for a flare at 8.59 μm (22.4 mJy with A 8.59 μm = 1.6 ± 0.5). This observational constraint makes us discard the observed NIR emission as coming from a thermal component emitting at sub-mm frequencies. Moreover, comparison of the sub-mm and NIR variability shows that the highest NIR fluxes (flares) are coincident with the lowest sub-mm levels of our five-night campaign involving three flares. We explain this behavior by a loss of electrons to the system and/or by a decrease in the magnetic field, as might conceivably occur in scenarios involving fast outflows and/or magnetic reconnection.

show abstract

Massive Black Holes: Evidence, Demographics and Cosmic Evolution

Genzel

2021

The Universe

View full text Add to dashboard Cite

The article summarizes the observational evidence for the existence of massive black holes, as well as the current knowledge about their abundance, their mass and spin distributions, and their cosmic evolution within and together with their galactic hosts. We finish with a discussion of how massive black holes may in the future serve as laboratories for testing the theory of gravitation in the extreme curvature regimes near the event horizon.

show abstract

EVIDENCE FOR X-RAY SYNCHROTRON EMISSION FROM SIMULTANEOUS MID-INFRARED TO X-RAY OBSERVATIONS OF A STRONG Sgr A* FLARE

Cited by 171 publications

References 62 publications

Millimeter to X-ray flares from Sagittarius A*

Millimeter to X-ray flares from Sagittarius A*

Flares and variability from Sagittarius A*: five nights of simultaneous multi-wavelength observations

Massive Black Holes: Evidence, Demographics and Cosmic Evolution

Contact Info

Product

Resources

About