Abstract for Proposal 088486
Using the newly discovered X-ra- IR Type-I bursts to probe jet-disk interaction
During AO 18 our team discovered the presence of two IR bursts lagging
thermonuclear Type-I X-ray bursts: this allowed us to put the first
constraints on the orbital period of the source 4U 1728-34. Moreover, the
profiles of the newly discovered IR bursts showed intriguing 'dips' just
after the onset of the X-ray bursts. The aim of this proposal is to use
the novel method of X-ray-IR burst lag to measure the orbital period of
4U 1728-34 and two other sources, and to quantify the presence of 'dips'
in their IR reverberation, signatures that would indicate burst-induced
changes in the geometry of the accretion flow. We therefore ask to
perform 4 (total 56ks) XMM pointings to be matched by 4 (total 14h)
HAWK-I@VLT observations of 4U 1728-34, 4U 1705-44 and 4U 1636-53.
Details on Observing Strategy and Trigger Criteria
Reaction time needed >= 7 days (as required for joint XMM/VLT proposal)
Triggers: 4U 1728-34: 1 Trigger when the source is the soft state (Swift
BAT <0.01 count per second) 1 Trigger when the source is the hard state
(Swift BAT >=0.01 count per second) 4U 1705-44: 1 Trigger when the source
is the hard state(i.e. MAXI count rate < 0.5 count per sec) 4U 1636-53
1 Trigger when the source is the hard state(i.e. MAXI count rate <
0.4 count per sec)