Alex Gormaz Matamala (Astronomical Institute of the Czech Academy of Sciences)
Mass loss shapes the evolution and final fates of massive stars through their OB, RSG and WR phases. Revised line-driven wind prescriptions predict weaker winds during the OB phases, spanning ~90% of a massive star's lifetime. We present evolutionary models from the Galactic Centre (Z=0.020) to the Small Magellanic Cloud (Z=0.002), exploring changes in HR diagram tracks, surface rotation and chemical enrichment. At high metallicity, weaker winds retain outer layers and slow surface chemical evolution; at low metallicity, they enhance rotational mixing and accelerate surface enrichment. At the Galactic Centre, reduced early mass loss yields less homogeneous Wolf-Rayet (WR) stars and fewer hydrogen-free WN stars, improving agreement with observations. We derive H, He and CNO abundances for Ofpe/WN9, WNL, WN/C and WC subtypes and propose a revised subtype classification for wind-collision bow shocks to inform accretion models for Sgr A*. We also investigate how self-consistent wind hydrodynamic profiles, replacing the beta-law, modify wind configurations, hydrogen columns and accretion rates in high-mass X-ray binaries. Finally, we examine line-driven wind prescriptions near the Eddington limit. We introduce an O-to-WR wind-transition criterion to replace the classical hydrogen mass-fraction threshold and study its impact in the generation of black holes progenitors of gravitational waves.
Scott Hagen (SISSA Trieste)
Active galactic nuclei (AGN) are powered by accretion onto a supermassive black hole (SMBH). Observations show that these vary on week-year timescales in the optical/UV and day-weeks in the X-ray. This is in stark contrast to standard accretion theory which predicts that they can only vary on ~10^5 year timescales, suggesting significant limitations in our understanding of accretion onto SMBHs. In this talk I will discuss how AGN variability provide an opportunity to study the physical conditions and structure of the accretion flow; from the central flow near the SMBH to outer large scale height structures such as the broad line region (BLR) and winds. I will show how modelling assuming a modified, intrinsically variable, disc structure can qualitatively match the observed variability properties; albeit with some limitations. I will further show results from a number of recent monitoring campaigns that highlight not only intrinsic variability, but also extrinsic variations caused by obscuring winds and variations in the BLR. Finally, I will briefly discuss the prospects for the upcoming ESA flagship mission NewAthena to probe the link between the inner flow and large scale structures (e.g. winds, the BLR) through a subset of sources displaying extreme variations in their inner structure.
Agnieszka Janiuk (CFT PAN)
Federico Gonzalez (Universidad Nacional de San Juan)
Radek Poleski (OAUW)
Christian Ikechukwu Eze (CAMK PAN)
Leatitia Gibaud (University of Białystok)
Mikołaj Korzyński (CFT PAN)
Sebastian Trojanowski (Astrocent)
Parikshit Biswas (CAMK, Warsaw)
