Rethinking Thorne-Żytkow Object Formation: The Fate of X-ray Binary LMC X-4 and Implications for Ultra-long Gamma-ray Bursts

Abstract

We present a start-to-end simulation aimed at studying the long-term fate of high-mass X-ray binaries and whether a Thorne-Żytkow object (TŻO) might ultimately be assembled. We analyze results from a 3D hydrodynamical simulation that models the eventual fate of LMC X-4, a compact high-mass X-ray binary system, after the primary fills its Roche lobe and engulfs the neutron star companion. We discuss the outcome of this engulfment within the standard paradigm of TŻO formation. The post-merger angular momentum content of the stellar core is a key ingredient, as even a small amount of rotation can break spherical symmetry and produce a centrifugally supported accretion disk. Our findings suggest the inspiraling neutron star, upon merging with the core, can accrete efficiently via a disk at high rates ($\approx 10^{-2}{M}_{\odot }/\mathrm{s}$), subsequently collapsing into a black hole and triggering a bright transient with a luminosity and duration typical of an ultra-long gamma-ray burst. We propose that the canonical framework for TŻO formation via common envelope needs to be revised, as the significant post-merger accretion feedback will unavoidably unbind the vast majority of the surrounding envelope.

References in corpus (26)

• The NumPy array: a structure for efficient numerical computation
• Modules for Experiments in Stellar Astrophysics (MESA)
• Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
• The Evolution of Compact Binary Star Systems
• Catalogue of high-mass X-ray binaries in the Galaxy ($4^{th}$ edition)
• The ephemeris, orbital decay, and masses of 10 eclipsing HMXBs
• Asymmetric Accretion Flows within a Common Envelope
• The Properties of Short gamma-ray burst Jets Triggered by neutron star mergers
• On the Accretion-Fed Growth of Neutron Stars During Common Envelope
• Violent Stellar Merger Model for Transient Events
• Black hole to breakout: 3D GRMHD simulations of collapsar jets reveal a wide range of transients
• Discovery of a Thorne-Zytkow object candidate in the Small Magellanic Cloud
• Accretion Disk Assembly During Common Envelope Evolution: Implications for Feedback and LIGO Binary Black Hole Formation
• Light Curve Model for Luminous Red Novae and Inferences about the Ejecta of Stellar Mergers
• Simulating Black Hole White Dwarf Encounters
• The VMC survey -- XLIV: Mapping metallicity trends in the Large Magellanic Cloud using near-infrared passbands
• HV2112, a Thorne-Zytkow Object or a Super Asymptotic Giant Branch Star
• Do high-spin high-mass X-ray binaries contribute to the population of merging binary black holes?
• The Missing Link Between Black Holes in High-Mass X-ray Binaries and Gravitational-Wave Sources: Observational Selection Effects
• Cool, Luminous, and Highly Variable Stars in the Magellanic Clouds from ASAS-SN: Implications for Thorne-Żytkow Objects and Super-Asymptotic Giant Branch Stars
• The Art of Modeling Stellar Mergers and the Case of the B[e] Supergiant R4 in the Small Magellanic Cloud
• Observational predictions for Thorne-Żytkow objects
• On the maximum stellar rotation to form a black hole without an accompanying luminous transient
• Dusty, Self-obscured Transients from Stellar Coalescence
• Common Envelope Wind Tunnel: Range of Applicability and Self-Similarity in Realistic Stellar Envelopes
• Density Profiles of Collapsed Rotating Massive Stars Favor Long Gamma-Ray Bursts

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• Neutron Star-Main Sequence Collisions Robustly Form Dynamically Stable Thorne-Żytkow Objects
• Hyperaccreting Neutron Stars inside Massive Envelopes: The Implausibility of Thorne-Żytkow Objects