SIMBAD references

2011ApJ...728...37D - Astrophys. J., 728, 37 (2011/February-2)

The two states of Sgr A* in the near-infrared: bright episodic flares on top of low-level continuous variability.

DODDS-EDEN K., GILLESSEN S., FRITZ T.K., EISENHAUER F., TRIPPE S., GENZEL R., OTT T., BARTKO H., PFUHL O., BOWER G., GOLDWURM A., PORQUET D., TRAP G. and YUSEF-ZADEH F.

Abstract (from CDS):

In this paper, we examine properties of the variable source Sgr A* in the near-infrared (NIR) using a very extensive Ks-band data set from NACO/VLT observations taken in 2004-2009. We investigate the variability of Sgr A* with two different photometric methods and analyze its flux distribution. We find that Sgr A* is continuously emitting and continuously variable in the near-infrared, with some variability occurring on timescales as long as weeks. The flux distribution can be described by a lognormal distribution at low intrinsic fluxes ( ≲ 5 mJy, dereddened with AKs= 2.5). The lognormal distribution has a median flux of ~1.1 mJy, but above 5 mJy the flux distribution is significantly flatter (high flux events are more common) than expected for the extrapolation of the lognormal distribution to high fluxes. We make a general identification of the low-level emission above 5 mJy as flaring emission and of the low-level emission as the quiescent state. We also report here the brightest Ks-band flare ever observed (from 2008 August 5) which reached an intrinsic Ks-band flux of 27.5 mJy (mKs = 13.5). This flare was a factor 27 increase over the median flux of Sgr A*, close to double the brightness of the star S2, and 40% brighter than the next brightest flare ever observed from Sgr A*.

Abstract Copyright:

Journal keyword(s): accretion, accretion disks - black hole physics - Galaxy: center - infrared: general

CDS comments: Objects S21, S30, S31, S60, S62, and S65 are not in Simbad due to a lack of coordinates.

Simbad objects: 7

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2021.11.30-01:15:22

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