Probing Super-Eddington Outflows via Accreting Galactic BeXRBs

Observations of the population of ultra luminous X-ray sources has revealed that at least a subset of this group contains a neutron star primary. Thus, dramatically demonstrating the viability of super-Eddington accretion for this source class. However, the physics of these super-Eddington accretion flows are poorly understood with the sources typically lying at Mpc distances. The population of Galactic Be/X-ray binaries (BeXRBs) are known to have giant outbursts that enter the super-Eddington regime and promise the opportunity to learn much about this mode of accretion. Herein, we propose to obtain simultaneous high resolution X-ray, UV and radio spectroscopy of the next bright Galactic BeXRB to enter a giant outburst when the neutron star will be accreting in the super-Eddington regime.