Thermal and Nonthermal Emission from the Extragalactic Microquasar S26

LEANDRO ABAROA

Paris

Congreso; Conference on High Energy Phenomena in Relativistic Outflows; 2023

Observatorio Astronómico de París, Universidad Sorbona

S26 is a unique microquasar that exhibits the most powerful jets observed in accreting binaries, with a kinetic luminosity of Ljet = 1040 erg s-1. According to the jet-disk symbiosis model, this implies that the accretion luminosity onto the stellar black hole should be highly super-Eddington, of the order of Lacc ≈ Ljet, to power the jet. However, the observed X-ray luminosity of this system, as measured by Chandra and XMM-Newton telescopes, indicates an apparent very sub-Eddington accretion luminosity with Lacc ≈ 1036 erg s-1, not enough to explain the jet power. In this contribution, we present a study of the thermal and nonthermal radiation of S26 and we explore the relation between the jet and disk in this source. We analyze multi-epoch X-ray observations of S26 obtained with XMM-Newton and NuSTAR space telescopes and we develop a jet model to explain the emission. We investigate particle acceleration and radiative processes that occur in adiabatic shocks generated at the base of the jet and at the termination region, where the jet interacts with the interstellar medium. We also discuss the paucity of thermal X-rays from the accreting gas. Our results provide some insights into the nature of this peculiar source.