September 23, 2015
from NASA Website
Scientists are trying to learn whether
this is normal behavior that was unnoticed due to limited
monitoring, or these flares are triggered by the recent close
passage of a mysterious, dusty object.
supermassive black hole, a.k.a.
Sagittarius A*, weighs in at
slightly more than 4 million times the mass of the Sun. X-rays are
produced by hot gas flowing toward the black hole.
This increase happened soon after the close approach to Sgr A* by a mysterious object called G2.
Originally, astronomers thought G2 was an extended cloud of gas and dust. However, after passing close to Sgr A* in late 2013, its appearance did not change much, apart from being slightly stretched by the gravity of the black hole.
This led to new theories that G2 was not simply a gas cloud, but instead a star swathed in an extended dusty cocoon.
While the timing of G2's passage with the surge in X-rays from Sgr A* is intriguing astronomers see other black holes that seem to behave like Sgr A*.
Therefore, it's possible this increased chatter from Sgr A* may be a common trait among black holes and unrelated to G2.
For example, the increased X-ray activity could be due to a change in the strength of winds from nearby massive stars that are feeding material to the black hole.
The analysis included 150 Chandra and XMM-Newton observations pointed at the center of the Milky Way over the last 15 years, extending from September 1999 to November 2014.
An increase in the rate and brightness
of bright flares from Sgr A* occurred after mid-2014, several months
after the closest approach of G2 to the huge black hole.
It then could have started interacting
with hot material flowing towards the black hole, funneling more gas
toward the black hole that could later be consumed by Sgr A*.
Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington.
The Smithsonian Astrophysical
Observatory in Cambridge, Massachusetts, controls Chandra's science
and flight operations.