Speaker
Description
It is widely accepted that Type-B quasi-periodic oscillations (QPOs) are causally connected to discrete ejections of relativistic jets in black hole X-ray binaries. Here, I present new results from a bright flare of Swift J1727.8−1613, during which the source evolved from the hard intermediate state (HIMS) into the soft intermediate state (SIMS) and almost immediately back to the HIMS, without progressing into the high-soft state (HSS).
During this brief excursion into the SIMS, the broadband X-ray variability drops and discrete, optically thin radio ejections are observed, as typically seen during transitions into the SIMS.
Using a novel joint power and cross-spectrum fitting technique, I show that the Type-B QPO is already present during the HIMS, and hence not physically associated with the discrete jet ejections. Initially, the Type-B QPO is hidden beneath the stronger Type-C QPO and dominant broadband variability. As the Type-C QPO disappears, broadband noise weakens, and the steady compact radio jet vanishes, the Type-B QPO becomes detectable and dominates the variability, and the power spectrum changes from Type-C to Type-B.
These results challenge models that interpret the power spectrum as a single broadband component, favoring instead a picture where distinct variability components coexist, each with their own QPOs. The disappearance of the Type-C power spectrum alongside the steady radio jet suggests a close link between them.
I will present these findings for Swift J1727.8−1613, complemented by results from MAXI J1820+070, and discuss their implications for the structure of variability and the formation of jets in black-hole binaries.
| Contribution | Oral talk |
|---|---|
| Affiliation | Kapteyn Astronomical Institute, University of Groningen |
| mariano@astro.rug.nl |
