Gravitational Waves From Accreting Neutron Stars Undergoing Common-envelope Inspiral

The common-envelope phase is a possible channel for the formation of compact binaries, such as binary neutron stars and/or black hole-neutron star binaries. This phase involves two stars that share a single envelope in which their orbit decays due to dynamical friction. Neutron stars that undergo common-envelope inspiral accrete at a fraction of the Bondi-Hoyle-Lyttleton accretion rate since the stellar envelope is inhomogeneous. Accreting neutron stars are candidate sources of gravitational waves and have been studied in the context of low-mass X-ray binaries and fall-back accretion following supernova events. I will discuss neutron stars in the common-envelope phase as gravitational-wave sources. We find that accreting neutron stars undergoing common-envelope inspiral are detectable sources of gravitational waves in the Advanced LIGO band. Such a detection may be used to constrain the properties of detected common-envelope binaries, such as the orbital separation. Such a detection would also provide new insights into common-envelope evolution and its role in forming compact binaries.