Abstract
We present the first systematic analysis of the X-ray variability of Sgr A* during the Chandra X-ray Observatory's 2012 Sgr A* X-ray Visionary Project. With 38 High Energy Transmission Grating Spectrometer observations spaced an average of 7 days apart, this unprecedented campaign enables detailed study of the X-ray emission from this supermassive black hole at high spatial, spectral and timing resolution. In 3 Ms of observations, we detect 39 X-ray flares from Sgr A*, lasting from a few hundred seconds to approximately 8 ks, and ranging in 2-10 keV luminosity from 1034 erg s-1 to 2 × 1035 erg s-1. Despite tentative evidence for a gap in the distribution of flare peak count rates, there is no evidence for X-ray color differences between faint and bright flares. Our preliminary X-ray flare luminosity distribution dN/dL is consistent with a power law with index ; this is similar to some estimates of Sgr A*'s near-IR flux distribution. The observed flares contribute one-third of the total X-ray output of Sgr A* during the campaign, and as much as 10% of the quiescent X-ray emission could be comprised of weak, undetected flares, which may also contribute high-frequency variability. We argue that flares may be the only source of X-ray emission from the inner accretion flow.
Original language | English (US) |
---|---|
Article number | 42 |
Journal | Astrophysical Journal |
Volume | 774 |
Issue number | 1 |
DOIs | |
State | Published - Sep 1 2013 |
Keywords
- accretion, accretion disks
- black hole physics
- radiation mechanisms: non-thermal
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science