SIMBAD references

2016MNRAS.456.1438Y - Mon. Not. R. Astron. Soc., 456, 1438-1450 (2016/February-3)

A systematic Chandra study of Sgr A* - I. X-ray flare detection.

YUAN Q. and WANG Q.D.

Abstract (from CDS):

Daily X-ray flaring represents an enigmatic phenomenon of Sagittarius A{sstarf} (Sgr A{sstarf}) - the supermassive black hole at the centre of our Galaxy. We report initial results from a systematic X-ray study of this phenomenon, based on extensive Chandra observations obtained from 1999 to 2012, totalling about 4.5 Ms. We detect flares, using a combination of the maximum likelihood and Markov Chain Monte Carlo methods, which allow for a direct accounting for the pileup effect in the modelling of the flare light curves and an optimal use of the data, as well as the measurements of flare parameters, including their uncertainties. A total of 82 flares are detected. About one third of them are relatively faint, which were not detected previously. The observation-to-observation variation of the quiescent emission has an average root-mean-square of 6-14 percent, including the Poisson statistical fluctuation of faint flares below our detection limits. We find no significant long-term variation in the quiescent emission and the flare rate over the 14 years. In particular, we see no evidence of changing quiescent emission and flare rate around the pericentre passage of the S2 star around 2002. We show clear evidence of a short-term clustering for the Advanced CCD Imaging Spectrometer - Spectroscopy array/high energy transmission gratings 0th-order flares on time-scale of 20-70 ks. We further conduct detailed simulations to characterize the detection incompleteness and bias, which is critical to a comprehensive follow-up statistical analysis of flare properties. These studies together will help to establish Sgr A{sstarf} as a unique laboratory to understand the astrophysics of prevailing low-luminosity black holes in the Universe.

Abstract Copyright: © 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2015)

Journal keyword(s): accretion, accretion discs - methods: data analysis - Galaxy: centre - X-rays: individual: (Sgr A{sstarf})

Status at CDS : Large table(s) will be appraised for possible ingestion in VizieR.

Simbad objects: 5

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2021.12.09-13:55:55

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