The paper includes the detection and analysis of an additional dipping event in Aql X-1, along with a search for similar events in 24 other bursting low-mass X-ray binaries.
Figure 1. X-ray intensity of Aql X-1 during the RXTE
observation on 2011 October 21 (obsid #96440-01-02-02). Shown is the 1-s
binned lightcurve of the Standard-1 mode data, which includes photons in
the energy range 2-60 keV. Note the multiple deep dip features, numbered
1, 2, 3a, 3b and 4; the thick black lines indicate the extent of
spectral extraction for each dip. The lightcurve has been background
subtracted and corrected to the solar system barycentre.
Figure 2. X-ray intensity of Aql X-1 on 2011 October 21 as a
function of energy, calculated from 16-s binned Standard-2 mode
data. The X-ray intensity in the
2-3.7 keV, 3.7-4.9 keV, 4.9-8.6 keV and 8.6-17.7 keV bands (top
panel) shows that the dip is deepest at lower energies, producing an
overall harder X-ray spectrum. This hardening of the spectrum is confirmed
by the soft and hard X-ray colours (calculated from the ratio of 3.7-4.9
keV to 2-3.7 keV intensity, and 8.6-17.7 keV to 4.9-8.6 keV, respectively;
bottom panel).
Duncan.Galloway@monash.edu
13thth July 2016