Evaluating chemically homogeneous evolution in stellar binaries: Electromagnetic implications -- Ionizing photons, SLSN-I, GRB, Ic-BL

Understand

We investigate the occurrence of rapid-rotation induced chemically homogeneous evolution (CHE) due to strong tides and mass accretion in binaries.

• To this end, we generalize the relation in Packet (1981) to calculate the minimum angular momentum (AM) accretion required by a secondary star to experience accretion-induced CHE.
• Contrary to traditionally assumed 5-10 percent accretion of initial mass ($Z \lesssim 0.004$, $M \gtrsim$ 20 M$_{\odot}$) for spinning up the accretor (resulting in CHE) this value can drop to $\sim$ 2 percent for efficient AM accretion while for certain systems it could be substantially larger.
• We conduct a population study using \textsc{bpass} by evolving stars under the influence of strong tides in short-period binaries and also account for the updated effect of accretion-induced spin-up.