Population synthesis of Thorne-Żytkow objects: Rejuvenated donors and unexplored progenitors in the common envelope formation channel

Abstract

Context. Common envelope evolution of a massive star and a neutron star companion has two possible outcomes: formation of a short-period binary (a potential gravitational wave source progenitor) or a merger of the massive star with the neutron star. If the binary merges, a structure with a neutron star core surrounded by a large diffuse envelope, a so-called Thorne-Żytkow object (TŻO), may form. The predicted appearance of this hypothetical class of star is very similar to red supergiants, making observational identification difficult. Aims. Our objective is to understand the properties of systems that are potential TŻO progenitors, e.g., binary systems that enter a common envelope phase with a neutron star companion. We also aim to distinguish those that have been through a previous stable mass transfer phase, which can rejuvenate the accretor. We estimate the number of TŻOs in the Milky Way and assess the impact of uncertainties in their formation. Methods. We use the rapid population synthesis code COMPAS at Solar metallicity and with common envelope efficiency parameter set to unity to determine the population demographics of TŻOs. We use one-dimensional evolutionary TŻO models from the literature to determine a fit for TŻO lifetime in order to estimate the current number of TŻOs in the Galaxy as well as to assess core disruption during the merger. Results. We explore the progenitors in the Hertzsprung-Russell diagram, calculate formation rates, and investigate kinematics of the progenitor stars. We find that the vast majority ($\approx 92\%$) of TŻO progenitors in our population have experienced mass transfer and become rejuvenated before their formation event. Using a constant star formation rate we estimate $\approx 2\times 10^{-4}$ TŻOs per $M_{\odot }$ in our Galaxy, corresponding to $\approx 5\pm 1$ TŻOs in the Milky Way at present.

12 pages, 6 figures. Accepted in A&A

References in corpus (39)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Binary interaction dominates the evolution of massive stars
• Pre-Supernova Evolution of Massive Single and Binary Stars
• Formation of Double Neutron Star Systems
• Mind the gap: The location of the lower edge of the pair instability supernovae black hole mass gap
• Double neutron stars: merger rates revisited
• The ephemeris, orbital decay, and masses of 10 eclipsing HMXBs
• Pair creation supernovae at low and high redshift
• Impact of Massive Binary Star and Cosmic Evolution on Gravitational Wave Observations I: Black Hole-Neutron Star Mergers
• Mass Transfer from Giant Donors
• Adiabatic mass loss in binary stars. III. From the base of the red giant branch to the tip of asymptotic giant branch
• The Star Formation Rate of the Milky Way as seen by Herschel
• Detecting Double Neutron Stars with LISA
• Explaining iPTF14hls as a common envelope jets supernova
• Numerical Simulations of Convective 3-Dimensional Red Supergiant Envelopes
• Coping with loss: Stability of mass transfer from post-main sequence donor stars
• Discovery of a Thorne-Zytkow object candidate in the Small Magellanic Cloud
• Gravitational wave sources in our Galactic backyard: Predictions for BHBH, BHNS and NSNS binaries detectable with LISA
• Rejuvenated accretors have less bound envelopes: Impact of Roche lobe overflow on subsequent common envelope events
• A transient radio source consistent with a merger-triggered core collapse supernova
• Long-term Evolution of Binary Orbits Induced by Circumbinary Disks
• A common envelope jets supernova (CEJSN) impostor scenario for fast blue optical transients
• HV2112, a Thorne-Zytkow Object or a Super Asymptotic Giant Branch Star
• Neutron stars colliding with binary companions: formation of hypervelocity stars, pulsar planets, bumpy superluminous supernovae and Thorne-Żytkow objects
• Stellar Core-Merger-Induced Collapse: New Formation Pathways for Black Holes, Thorne-$\dot{\mathrm{Z}}$ytkow objects, Magnetars and Superluminous Supernovae
• Evolution and final fate of massive post-common-envelope binaries
• Planet Hunters TESS IV: A massive, compact hierarchical triple star system TIC 470710327
• 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 Asteroseismic Imprints of Mass Transfer: A Case Study of a Binary Mass Gainer in the SPB Instability Strip
• Core radii and common-envelope evolution
• Confirming NGC 6231 as the parent cluster of the runaway high-mass X-ray binary HD 153919/4U 1700-37 with Gaia DR2
• Observational predictions for Thorne-Żytkow objects
• Dissecting the microphysics behind the metallicity-dependence of massive stars radii
• Mergers of neutron stars and black holes with cores of giant stars: a population synthesis study
• Prospects for Multimessenger Observations of Thorne-Żytkow Objects
• Cool, Luminous, and Highly Variable Stars in the Magellanic Clouds. II: Spectroscopic and Environmental Analysis of Thorne-Żytkow Object and Super-AGB Star Candidates
• Three Dimensional Natures of Massive Star Envelopes
• Development of convective envelopes in massive stars: Implications for gravitational wave sources
• Common envelope jets supernova with thermonuclear outburst progenitor for the enigmatic supernova remnant W49B

Cited by in corpus (2)

• Development of convective envelopes in massive stars: Implications for gravitational wave sources
• Thorne-Żytkow Objects