Neutron Star Mergers in AGN Accretion Disks: Cocoon and Ejecta Shock Breakouts

Understand

Neutron star mergers are believed to occur in accretion disks around supermassive black holes.

• Here we show that a putative jet launched from the merger of a binary neutron star (BNS) or a neutron star--black hole (NSBH) merger occurring at the migration trap in an active galactic nucleus (AGN) disk would be choked.
• The jet energy is deposited within the disk materials to power a hot cocoon.
• The cocoon is energetic enough to break out from the AGN disk and produce a bright X-ray shock breakout transient peaking at $\sim0.15\,{\rm d}$ after the merger.