Population III star formation in an X-ray background: III. Periodic radiative feedback and luminosity induced by elliptical orbits

Understand

We model Pop III star formation in different FUV and X-ray backgrounds, including radiation feedback from protostars.

• We confirm previous results that a moderate X-ray background increases the number of Pop III systems per unit cosmological volume, but masses and multiplicities of the system are reduced.
• The stellar mass function also agrees with previous results, and we confirm the outward migration of the stars within the protostellar discs.
• We find that nearly all Pop III star systems are hierarchical, i.e., binaries of binaries.