X-Ray Binaries & Accretion Physics: Foundations

Systems can be fed by Roche-lobe overflow or by capture from a stellar wind. The inflow often forms an accretion disk with a hot inner region, corona, winds, and in some cases relativistic jets. Neutron-star systems may also show bursts or pulsations from a material surface and magnetic field.

Angular momentum forces transferred gas into orbit before it can fall inward. Magnetic or turbulent stresses move angular momentum outward, allowing matter to spiral inward and convert gravitational binding energy into heat and radiation.

X-ray spectra, rapid variability, Doppler-shifted companion-star lines, eclipses, and orbital mass functions reveal compact objects. Chandra and other X-ray observatories resolve binaries in the Milky Way and external galaxies.

X-ray binaries reveal compact objects through matter falling from a companion star. Gravitational energy released in the accretion flow can make the system enormously luminous even when the black hole or neutron star itself is optically faint.