Abstract
Kilohertz quasi-periodic oscillations (kHz QPOs) offer the exciting
possibility of detecting, for the first time, the presence of the
marginally stable orbit (MSO) around a neutron star. Since the MSO has
an impact on the dynamics of matter in orbit around the neutron star, if
the kHz QPOs are produced in an accretion disc around the neutron star
the MSO should also affect the properties of these QPOs. Models predict
that all three characteristic properties of the kHz QPOs, their central
frequency, amplitude, and coherence, should display specific trends as
the radial position in the accretion disc where the oscillations are
produced approaches the radius of the MSO. Interestingly, these trends
have been observed in a handful of sources of kHz QPOs. I have recently
argued that (part of) those trends may in fact be due to changes in the
properties of the accreting gas that modulates the X-ray flux that makes
the QPOs visible. Here I will summarize the status of this conundrum,
and I will show results from recent observations of a source of kHz QPOs
that appear to resolve this issue.
| Original language | English |
|---|---|
| Pages | 2002 |
| Publication status | Published - 2008 |
| Event | 37th COSPAR Scientific Assembly. Held 13-20 July 2008 - Montréal, Canada Duration: 13-Jul-2008 → 20-Jul-2008 |
Conference
| Conference | 37th COSPAR Scientific Assembly. Held 13-20 July 2008 |
|---|---|
| Country/Territory | Canada |
| City | Montréal |
| Period | 13/07/2008 → 20/07/2008 |