Dominant radiative mechanism of QPE emission

Determine the dominant radiative mechanism responsible for the observed soft X-ray emission during quasi-periodic eruptions (QPEs) in eRO-QPE1, establishing whether the emission is primarily blackbody radiation, optically thin bremsstrahlung, Compton up-scattering, or another process, in order to correctly interpret the spectral evolution and inferred emitting region during the eruptions.

Background

The paper analyzes three and a half years of NICER and XMM-Newton observations of the QPE source eRO-QPE1, finding consistent short-term expansion and cooling of the inferred emitting region across eruptions and complex long-term evolution in luminosity and size. Within EMRI–disk collision models, the X-ray emission is thought to originate from shock-heated disk material ejected by the orbiting companion. However, the authors highlight that the precise radiative process generating the observed X-ray spectra remains unsettled.

Clarifying whether the X-ray emission is dominated by blackbody radiation, bremsstrahlung, Compton up-scattering, or another mechanism is crucial for correctly inferring physical properties (e.g., emitting area, expansion speed) and for connecting observed spectral-temporal behavior to the underlying dynamics of disk–companion interactions.