Quasi Periodic Oscillation
The data are X-ray light curves from a galactic binary
system, formed of 2 stars of which one has collapsed to a compact
object, very probably a black hole of a few solar masses. Gas from the
companion star is attracted to the black hole and forms an accretion
disk around it, and in this disk turbulence occurs which causes the gas
to accrete slowly to the black hole. The X-rays we see come from the
disk and its corona, heated by the energy released as the gas falls
deeper into the potential well of the black hole.
The data were obtained by RXTE, an X-ray satellite dedicated to the
observation of this kind of sources, and in particular their fast
variability which informs us on the proceses in the disk. In particular
they show a QPO (quasi-periodic oscillation) at a varying frequency of
the order of 1 to 10 Hz, which probably
corresponds to a standing feature rotating in the disk.
Observations were obtained in a 1000s interval, in 5 energy bands
(2-5keV, 5-13keV,13-20keV,20-40keV, 40-60keV).
Spectrograms are represented in logarithm.
2-5keV band
Spectrograms and filtered spectogram by the ridgelet transform of the QPO in
the 2-5keV band.
5-13keV band.
Spectrograms and filtered spectogram by the ridgelet transform of the QPO in
the 5-13keV band.
13-20 keV band.
Spectrograms and filtered spectogram by the ridgelet transform of the QPO in
the 13-20keV band .
20-40 keV band.
Spectrograms and filtered spectogram by the ridgelet transform of the QPO in
the 20-40keV band.
40-60 keV band.
Spectrograms and filtered spectogram by the ridgelet transform of the QPO in
the 40-60keV band.