TY  - CONF
AU  - Stiele, Holger
AU  - Kong, Albert
TI  - Evolution of QPOs and spectral properties during X-ray binary outburst
M1  - FZJ-2024-06832
PY  - 2024
AB  - Low-mass black hole X-ray binaries are mainly transient systems. From time to time they go into outbursts, which usually last from a few weeks to several months and during which their luminosity changes by several orders of magnitude. During the outburst, these systems pass through different states with distinct spectral and short-term variability properties. NICER enables us to closely follow the evolution of these outbursts on a variety of time scales with high-sensitivity data. Based on these observations, we were able to study in detail the evolution of certain variability features, so-called quasi-periodic oscillations (QPOs), in different outburst states and during state transition. Our investigations allowed us to gain further insights into the evolution of QPOs and to follow the emergence and disappearance of the different types of these oscillations in more detail. We analysed not only power-density spectra, but also the evolution of energy spectra. Based on theoretical modelling, we determined the radii of the different components of X-ray binaries and followed their evolution during outburst.We will present the results of our studies of the evolution of the timing and spectral properties in outbursts of GX 339-4 and Swift J1727.7-1613. We will discuss them in light of different QPO models and what they teach us about the accretion geometry of X-ray binaries.
T2  - Joint NICER/IXPE Workshop 2024
CY  - 29 Jul 2024 - 1 Aug 2024, Washington D.C. (USA)
Y2  - 29 Jul 2024 - 1 Aug 2024
M2  - Washington D.C., USA
LB  - PUB:(DE-HGF)6
UR  - https://juser.fz-juelich.de/record/1033999
ER  -