Scientific Seminars

X-ray QPEs: what do we know three years after their discovery

Margherita Giustini
Centro de Astrobiologia (CSIC-INTA)

2021-12-02    11:00    Merate - Sala Virtuale - https://meet.google.com/imu-ibbn-cct

Serendipitously discovered at the end of 2018, quasi-periodic eruptions (QPEs) are intense, rapid, and recurrent bursts of X-ray emission over a stable level of quiescence. While the luminosity emitted during QPEs and the time scales involved imply a link to non-stationary accretion onto supermassive black holes (SMBHs), the physical interpretation of this new cosmic phenomenon is still far from clear. Possible physical scenarios to interpret QPEs include instabilities of the very inner accretion flow around SMBHs, gravitational lensing of SMBH binary accretion disks, multiple-body systems with one or more stellar-mass compact objects orbiting a SMBH; in any case, QPEs are telling us something important about SMBH accretion in low-mass galaxies. During this seminar I will recount the story of the discovery of QPEs and the progress made during the almost three years elapsed from their first detection, including many puzzling observational results which leave the theoretical interpretation of QPEs quite open.