BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Energy bookkeeping in black-hole growth DTSTART:20261021T090000Z DTEND:20261021T100000Z DTSTAMP:20261006T233800Z UID:indico-event-14@indico.icranet.org CONTACT:secretariat@icranet.org DESCRIPTION:Speakers: Shurui Zhang (ICRANet)\n\nBlack-hole (BH) accretion and mergers drive BH growth and power the most energetic phenomena in the universe\, yet how much energy is retained as transformable rotational ene rgy remains unclear. Using the irreducible mass to split a Kerr BH into an irreversible part and a transformable rotational reservoir\, we trace the evolution of each energy channel and compare the radiated and stored ener gies across different BH growth processes. For prograde conservative accre tion through the innermost stable circular orbit\, the rotational energy g ained exceeds the radiated energy over the broad spin range (0.07220.0894)\; thi s relation also holds across most of the eccentricities and spin configura tions explored. Observationally\, all LIGO–Virgo–KAGRA events from O1- O4 with publicly reported source parameters satisfy this relation. Our stu dies connect BH thermodynamics\, growth\, and energy extraction\, showing that across most astrophysically relevant parameters\, BH growth builds a rotational reservoir larger than the energy it directly radiates. This res ult helps us understand energy supply and transfer in extreme environments and enables studies of energy extraction from BHs to be more astrophysica lly meaningful.\n\n\n\n\nShurui Zhang is currently a postdoctoral fellow a t ICRANet. He received PhD degrees from both the University of Ferrara and USTC (University of Science and Technology of China). His research intere sts are on AGNs and compact objects via multi-messenger approaches.\n\n\n\ n \n\nhttps://indico.icranet.org/event/14/ URL:https://indico.icranet.org/event/14/ END:VEVENT END:VCALENDAR