Lyman-Werner Escape Fractions from the First Galaxies

Understand

Direct collapse black holes forming in pristine, atomically-cooling haloes at $z \approx 10-20$ may act as the seeds of supermassive black holes (BH) at high redshifts.

• In order to create a massive BH seed, the host halo needs to be prevented from forming stars.
• H$_2$ therefore needs to be irradiated by a large flux of Lyman-Werner (LW) UV photons in order to suppress H$_2$ cooling.
• A key uncertainty in this scenario is the escape fraction of LW radiation from first galaxies, the dominant source of UV photons at this epoch.