The MAXI X-ray transient - a unique Target of Opportunity
In the early morning of 25 September 2010, Japan's X-ray monitor
MAXI on-board the International Space Station detected a new transient
source, MAXI J1659-152, consistent with GRB 100925A detected by Swift/BAT.
The new detection has been followed by many high-energy observatories
as shown in the timeline above. First results indicate that this is
the shortest period high-inclination, black-hole candidate binary.
It's state has now changed from the canonical hard state in the
beginning of the outburst to the canonical soft state.
The three images at the top show different observations from the
INTEGRAL Galactic bulge monitoring program (18-40 keV)
( http://isdc.unige.ch/Science/BULGE/ ): before the MAXI detection
(revolution 966, 10-13 Sep), during the first observation after the
MAXI detection (971, 25-28 Sep) and during a phase of fading hard
X-ray emission (974, 4-7 Oct). The source is far off-axis, but still
within the large IBIS/ISGRI field of view, so that its behavior can
be monitored.
In addition to the bulge monitoring observations, INTEGRAL observed
MAXI J1659-152 in three dedicated ToO observations of 100 ksec each.
(PI: E. Kuulkers). During the first TOO observation a simultaneous
XMM-Newton observation was performed. The source is now not visible
anymore for INTEGRAL due to spacecraft viewing constraints.
The INTEGRAL observations fit it in with the wealth of observations
done and triggered at various wavelengths. We thus have a unique
opportunity to better understand what drives the transitions from
state to state, especially at high energies. Not many X-ray transients
do get this bright, so this is a rather unique opportunity.
Credit: E. Kuulkers, ISOC, ESA/ESAC on behalf of the Galactic bulge monitoring program team
