Source-Intrinsic Near-Infrared Properties of SGR A*: Total Intensity Measurements

Witzel, G.; Eckart, A.; Bremer, M.; Zamaninasab, M.; Shahzamanian, B.; Valencia-S., M.; Schödel, R.; Karas, V.; Lenzen, R.; Marchili, N.; Sabha, Nesrin; García-Marín, M.; Buchholz, Rainer; Kunneriath, D.; Straubmeier, C.

doi:10.1088/0067-0049/203/2/18

Cited by 126 publications

(233 citation statements)

References 93 publications

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“…For the years 2002 and 2009−2012 we did not find high-quality H-band imaging VLT data. The work of Bremer et al (2011) and Witzel et al (2012) as well as the comparison to published data suggests that the flux densities and colors of the sources we investigated are constant to within 40% and 80%. Table 4).…”

Section: Naco Near-infrared Imagingmentioning

confidence: 55%

“…Active optics guide star PSF width estimates obtained in the optical for all NACO K s -band data until 2010 are given in Fig. 20 by Witzel et al (2012). For the years 2002 and 2009−2012 we did not find high-quality H-band imaging VLT data.…”

Section: Naco Near-infrared Imagingmentioning

confidence: 84%

“…Sabha et al (2010Sabha et al ( , 2012 employed successive subtraction of stars in the S-star cluster. Witzel et al (2012) used the shape of the SgrA* flare amplitude histogram. The otherwise straight power spectrum with which this histogram can be described turns over at a flare flux density at which a mere flare detection becomes a flare flux density measurement (details in Witzel et al 2012).…”

Section: Statistical Robustness Of the Dso Identificationsmentioning

confidence: 99%

“…Witzel et al (2012) used the shape of the SgrA* flare amplitude histogram. The otherwise straight power spectrum with which this histogram can be described turns over at a flare flux density at which a mere flare detection becomes a flare flux density measurement (details in Witzel et al 2012). This indicates a confusion limit in the range of 0.5 to 1.5 mJy.…”

Section: Statistical Robustness Of the Dso Identificationsmentioning

confidence: 99%

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Near-infrared proper motions and spectroscopy of infrared excess sources at the Galactic center

Eckart¹,

Mužić²,

Yazici³

et al. 2013

A&A

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152

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Context. There are a number of faint compact infrared excess sources in the central stellar cluster of the Milky Way. Their nature and origin is unclear. In addition to several isolated objects of this kind there is a small but dense cluster of comoving sources (IRS13N) located ∼3 west of SgrA* just 0.5 north of the bright IRS13E cluster of Wolf-Rayet and O-type stars. Based on the analysis of their color and brightness, there are two main possibilities: (1) they may be dust-embedded stars older than a few Myr; or (2) very young, dusty stars with ages younger than 1 Myr. Aims. We present a first K s -band identification and proper motions of the IRS13N members, the high-velocity dusty S-cluster object (DSO, also referred to as G2), and other infrared excess sources in the central field. Goal is to constrain the nature of these source. Methods. The L -(3.8 μm) K s -(2.2 μm) and H-band (1.65 μm) observations were carried out using the NACO adaptive optics system at the ESO VLT. Proper motions were obtained by linear fitting of the stellar positions extracted by StarFinder as a function of time, weighted by positional uncertainties, and by Gaussian fitting from high-pass filtered and deconvolved images. We also present results of near-infrared (NIR) H-and K s -band ESO-SINFONI integral field spectroscopy of the Galactic center cluster ISR13N. Results. We show that within the uncertainties, the positions and proper motions of the IRS13N sources in K s -and L -band are identical. The HK−sL colors then indicate that the bright L -band IRS13N sources are indeed dust-enshrouded stars rather than core-less dust clouds. The proper motions also show that the IRS13N sources are not strongly gravitationally bound to each other. Combined with their NIR colors, this implies that they have been formed recently. For the DSO we obtain proper motions and a K s -L -color. Conclusions. Most of the compact L -band excess emission sources have a compact H-or K s -band counterpart and therefore are likely stars with dust shells or disks. Our new results and orbital analysis from our previous work favor the hypothesis that the infrared excess IRS13N members and other dusty sources close to SgrA* are young dusty stars and that star formation at the Galactic center (GC) is a continuously ongoing process. For the DSO the color information indicates that it may be a dust cloud or a dust-embedded star.

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Section: Naco Near-infrared Imagingmentioning

confidence: 55%

Section: Naco Near-infrared Imagingmentioning

confidence: 84%

Section: Statistical Robustness Of the Dso Identificationsmentioning

confidence: 99%

Section: Statistical Robustness Of the Dso Identificationsmentioning

confidence: 99%

See 2 more Smart Citations

Near-infrared proper motions and spectroscopy of infrared excess sources at the Galactic center

Eckart¹,

Mužić²,

Yazici³

et al. 2013

A&A

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152

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“…The IR flux distribution has been studied and reported by DoddsEden et al (2010) and Witzel et al (2012) using data from NACO/VLT in the Ks band (λ = 2.18µm, ν = 1.1 × 10 14 Hz). It was built by measuring the flux in 1 min long intervals.…”

Section: Introductionmentioning

confidence: 99%

Using infrared/X-ray flare statistics to probe the emission regions near the event horizon of Sgr A*

Dibi

Markoff

Belmont

et al. 2016

Mon. Not. R. Astron. Soc.

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The supermassive black hole at the centre of the Galaxy flares at least daily in the infrared (IR) and X-ray bands, yet the process driving these flares is still unknown. So far detailed analysis has only been performed on a few bright flares. In particular, the broadband spectral modelling suffers from a strong lack of simultaneous data. However, new monitoring campaigns now provide data on thousands of flaring events, allowing a statistical analysis of the flare properties. In this paper, we investigate the X-ray and IR flux distributions of the flare events.Using a self-consistent calculation of the particle distribution, we model the statistical properties of the flares. Based on a previous work on single flares, we consider two families of models: pure synchrotron models and synchrotron self-Compton (SSC) models. We investigate the effect of fluctuations in some relevant parameters (e.g. acceleration properties, density, magnetic field) on the flux distributions. The distribution of these parameters is readily derived from the flux distributions observed at different wavelengths.In both scenarios, we find that fluctuations of the power injected in accelerated particles plays a major role. This must be distributed as a power-law (with different indices in each model). In the synchrotron dominated scenario, we derive the most extreme values of the acceleration power required to reproduce the brightest flares. In that model, the distribution of the acceleration slope fluctuations is constrained and in the SSC scenario we constrain the distributions of the correlated magnetic field and flow density variations.

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The Galactic Black Hole

Morris¹

2022

Active Galactic Nuclei

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Source-Intrinsic Near-Infrared Properties of SGR A*: Total Intensity Measurements

Cited by 126 publications

References 93 publications

Near-infrared proper motions and spectroscopy of infrared excess sources at the Galactic center

Near-infrared proper motions and spectroscopy of infrared excess sources at the Galactic center

Using infrared/X-ray flare statistics to probe the emission regions near the event horizon of Sgr A*

The Galactic Black Hole

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