Different radio properties from rise and decay in GX 339-4 outbursts from Radio-X-ray data modelling
Abstract
Understanding the mechanisms of accretion-ejection during X-ray binaries' outbursts (XrB) has been a problem for 50 years. While a scientific consensus has emerged concerning the Standard Accretion Disk (SAD, Shakura & Sunyaev, 1973) as the origin of the soft X-ray emission, the nature of the inner hot flow (or corona) remains questioned. In 2018, Marcel et al. developed a two-temperature plasma code computing the spectrum of hybrid disks composed of a truncated outer SAD and an inner Jet Emitting Disk (JED, Ferreira 1997, Ferreira et al 2006, Petrucci et al 2008). We built JED-SAD model tables usable in Xspec, and we applied for the first time direct fitting procedures to the hard states of 4 outbursts of GX339-4 during the 2000-2010 decade (RXTE PCA X-ray spectra). Combined with simultaneous or quasi simultaneous (less than 1 day) radio observations, we were able to study simultaneously the radiative properties of the accretion flow and the jet, improving the qualitative work by Marcel et al. (2019). We are able to correctly fit the X-ray spectra and to reproduce the radio flux at better than 10-15%. Moreover, we show that the functional dependency of the radio emission on the model parameters (mainly the accretion rate and the transition radius between the JED and the SAD) is similar between all the rising phases of the different outbursts of GX 339-4. But it is significantly different from the functional dependency obtained in the decaying phases. This result strongly suggests a change in the radiative and/or dynamical properties of the ejection between the beginning and the end of the outburst. We will describe our methodology, present our results and discuss their implications in our understanding of accretion-ejection processes in BH XrB.
- Publication:
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43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E1229B