Stable case BB/BC mass transfer to form GW190425-like massive binary neutron star mergers

¹ Department of Physics, Anhui Normal University, Wuhu, Anhui 241002, China
² Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210023, China
³ School of Physics and Astronomy, Monash University, Clayton Victoria 3800, Australia
⁴ OzGrav: The ARC Centre of Excellence for Gravitational Wave Discovery, Clayton, Australia
⁵ Département d’Astronomie, Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland
⁶ Gravitational Wave Science Center (GWSC), Université de Genève, 24 quai E. Ansermet, 1211 Geneva, Switzerland
⁷ Nevada Center for Astrophysics, University of Nevada, Las Vegas, NV 89154, USA
⁸ Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154, USA
⁹ School of Astronomy and Space Science, Nanjing University, Nanjing 210093, People’s Republic of China
¹⁰ Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093, People’s Republic of China
¹¹ College of Physics, Guizhou University, Guiyang, Guizhou 550025, PR China
¹² Institute for Theoretical Physics and Cosmology, Zhejiang University of Technology, Hangzhou 310032, China
¹³ Guangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University, Nanning 530004, China
¹⁴ School of Physics and Physical Engineering, Qufu Normal University, Qufu, Shandong 273165, China
¹⁵ Department of Physics, School of Physics and Materials Science, Nanchang University, Nanchang 330031, China
¹⁶ School of Astronomy and Space Sciences, University of Science and Technology of China, Hefei 230026, China

^⋆ Corresponding authors; yingqin2013@hotmail.com, qwtang@ncu.edu.cn

Received: 10 July 2024
Accepted: 3 October 2024

Abstract

Context. On April 25, 2019, the LIGO-Virgo Collaboration discovered a gravitational-wave (GW) signal from a binary neutron star (BNS) merger, that is, GW190425. Due to the inferred large total mass, the origin of GW190425 remains unclear.

Aims. Assuming GW190425 originated from the standard isolated binary evolution channel, its immediate progenitor is considered to be a close binary system, consisting of a He-rich star and a NS just after the common envelope phase. We aim to study the formation of GW190425 in a solar-like environment by using the detailed binary evolution code MESA.

Methods. We perform detailed stellar structure and binary evolution calculations that take into account mass loss, internal differential rotation, and tidal interactions between a He-rich star and a NS companion. We explore the parameter space of the initial binary properties, including initial NS and He-rich masses and initial orbital period.

Results. We find that the immediate post-common-envelope progenitor system, consisting of a primary ∼2.0 M_⊙ (∼1.7 M_⊙) NS and a secondary He-rich star with an initial mass of ∼3.0 − 5.5 M_⊙ (∼5.5 − 6.0 M_⊙) in a close binary with an initial period of ∼0.08 − 0.5 days (∼0.08 − 0.4 days), that experiences stable Case BB/BC mass transfer (MT) during binary evolution, can reproduce the formation of GW190425-like BNS events. Our studies reveal that the secondary He-rich star of the GW190425’s progenitor before its core collapse can be efficiently spun up through tidal interaction, finally remaining as a NS with rotational energy even reaching ∼10⁵² erg, which is always much higher than the neutrino-driven energy of the supernova (SN) explosion. If the newborn secondary NS is a magnetar, we expect that GW190425 can be the remnant of a magnetar-driven SN, namely a magnetar-driven ultra-stripped SN, a superluminous SN, or a broad-line Type Ic SN.

Conclusions. Our results show that GW190425 could be formed through the isolated binary evolution, which involves a stable Case BB/BC MT just after the common envelope phase. On top of that, we show the He-rich star can be tidally spun up, potentially forming a spinning magnetized NS (magnetar) during the second SN explosion.