Origin of the binary pulsar J0737-3039B

Area of Science:

• * Astrophysics
• * Stellar Evolution
• * Binary Systems

Background:

• * The binary pulsar J0737-3039B presents an evolutionary puzzle regarding its progenitor's mass.
• * Previous models suggested a high-mass helium star progenitor (M > 2.1-2.3 solar masses).
• * Such a scenario implies a high center-of-mass velocity for the binary system.

Purpose of the Study:

• * To investigate the progenitor mass of the binary pulsar J0737-3039B.
• * To reconcile evolutionary models with the system's observed properties, including its galactic location and kinematics.
• * To constrain the rate of neutron star mergers.

Main Methods:

• * Analysis of the binary system's galactic location (50 pc from the Galactic plane).
• * Kinematic analysis, including center-of-mass velocity estimations.
• * Comparison of theoretical evolutionary scenarios with observational data and recent velocity measurements (66+/-15 km/s).

Main Results:

• * A high progenitor mass (>2.1 solar masses) is ruled out at 97% confidence based on kinematic and location data.
• * A lower progenitor mass (around 1.45 solar masses), involving a novel gravitational collapse, is kinematically favored.
• * The low-mass progenitor is consistent with recent velocity measurements, ruling out the high-mass solution at 99% confidence.

Conclusions:

• * The progenitor of J0737-3039B was likely a lower-mass star, challenging previous high-mass helium star scenarios.
• * This finding has implications for understanding neutron star formation pathways.
• * If the high-mass scenario were true, it would necessitate at least a doubling of estimated neutron star merger rates.