The Role of Strong Gravity and the Nuclear Equation of State on Neutron-Star Common-Envelope Accretion

Abstract

Common-envelope evolution is important in the formation of neutron star binaries within the isolated binary formation channel. As a neutron star inspirals within the envelope of a primary massive star, it accretes and spins up. Because neutron stars are in the strong-gravity regime, they have a substantial relativistic mass deficit, i.e., their gravitational mass is less than their baryonic mass. This effect causes some fraction of the accreted baryonic mass to convert into neutron star binding energy. The relativistic mass deficit also depends on the nuclear equation of state, since more compact neutron stars will have larger binding energies. We model the mass growth and spin-up of neutron stars inspiraling within common-envelope environments and quantify how different initial binary conditions and hadronic equations of state affect the post-common-envelope neutron star's mass and spin. From these models, we find that neutron star mass growth is suppressed by $\approx 15-30\%$. We also find that for a given amount of accreted baryonic mass, more compact neutron stars will spin-up faster while gaining less gravitational mass, and vice versa. This work demonstrates that a neutron star's strong gravity and nuclear microphysics plays a role in neutron-star-common-envelope evolution, in addition to the macroscopic astrophysics of the envelope. Strong gravity and the nuclear equation of state may thus affect both the population properties of neutron star binaries and the cosmic double neutron star merger rate.

11 pages, 6 figures, revised version accepted to ApJL

References in corpus (24)

• The NumPy array: a structure for efficient numerical computation
• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Modules for Experiments in Stellar Astrophysics (MESA)
• PSR J0030+0451 Mass and Radius from NICER Data and Implications for the Properties of Neutron Star Matter
• Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
• A NICER View of PSR J0030+0451: Millisecond Pulsar Parameter Estimation
• GW190425: Observation of a Compact Binary Coalescence with Total Mass $\sim 3.4M_{\odot }$
• Constraints on a phenomenologically parameterized neutron-star equation of state
• Formation of Double Neutron Star Systems
• Double neutron stars: merger rates revisited
• Asymmetric Accretion Flows within a Common Envelope
• Inferring neutron star properties from GW170817 with universal relations
• On the Accretion-Fed Growth of Neutron Stars During Common Envelope
• Double-core evolution and the formation of neutron-star binaries with compact companions
• On the origin of GW190425
• Asymmetric mass ratios for bright double neutron-star mergers
• Common-Envelope Episodes that lead to Double Neutron Star formation
• Disk formation and jet inclination effects in Common Envelopes
• Evolutionary Channels for the Formation of Double Neutron Stars
• Heavy double neutron stars: birth, mid-life and death
• Common-envelope Dynamics of a Stellar-mass Black Hole: General Relativistic Simulations
• The role of binding energies of neutron stars on the accretion driven evolution
• Masses of double neutron star mergers
• Common Envelope Wind Tunnel: Range of Applicability and Self-Similarity in Realistic Stellar Envelopes

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