Description
Low-mass X-ray binaries (LMXBs) provide an excellent laboratory for studying accretion physics and jet launching due to their rapid variability, which occurs on much shorter timescales than in supermassive black holes (SMBHs). This variability enables direct investigation of the interplay between accretion and jets, a fundamental open question in high-energy astrophysics, by linking X-ray emission from the accretion disk to radio emission from the jets.
GRS 1915+105, the most massive known LMXB and the first microquasar observed with superluminal jets, is unique in having sustained a high-luminosity outburst with extreme X-ray and radio variability for over three decades since its discovery in 1992. In mid-2018, the source entered a new phase of heavy X-ray obscuration, which was unexpectedly followed by a rapid rebrightening in the radio. This heavy obscuration is a first for GRS 1915+105 and has been attributed to increased local absorption due to enhanced disk winds. The enhanced winds were expected to suppress radio emission from the jets, yet the source displayed extreme radio variability. This challenges the standard X-ray/radio coupling observed in black hole binaries, where jets typically weaken as accretion declines.
This poster presents four high-resolution Very Long Baseline Interferometry (VLBI) observations, marking the first effort to understand how milliarcsecond-scale radio emission can remain bright during a phase of low X-ray variability. The results will determine whether the jets resemble compact hard-state jets or if they are enveloped in a disk wind that could be temporarily stalling the jet until it breaks out at a later stage. These findings may also provide insights into extragalactic ultra-luminous X-ray sources, which occasionally enter X-ray obscured phases but exhibit fainter radio emission than the Galactic LMXBs.
| Talk category | NOVA Network 3 |
|---|---|
| Preference for a talk or poster | Poster |
| Talk preference for PhD students | 1st year PhD student |
