Common-Envelope Episodes that lead to Double Neutron Star formation
Alejandro Vigna-Gómez, Morgan MacLeod, Coenraad J. Neijssel, Floor S. Broekgaarden, Stephen Justham, George Howitt, Selma E. de Mink, Serena Vinciguerra, Ilya Mandel
备注：
26 pages, 10 figures. Includes bug fix. Two new figures and an appendix added
Close double neutron stars have been observed as Galactic radio pulsars, while their mergers have been detected as gamma-ray bursts and gravitational-wave sources. They are believed to have experienced at least one common-envelope episode during their evolution prior to double neutron star formation. In the last decades there have been numerous efforts to understand the details of the common-envelope phase, but its computational modelling remains challenging. We present and discuss the properties of the donor and the binary at the onset of the Roche-lobe overflow leading to these common-envelope episodes as predicted by rapid binary population synthesis models. These properties can be used as initial conditions for detailed simulations of the common-envelope phase. There are three distinctive populations, classified by the evolutionary stage of the donor at the moment of the onset of the Roche-lobe overflow: giant donors with fully-convective envelopes, cool donors with partially-convective envelopes, and hot donors with radiative envelopes. We also estimate that, for standard assumptions, tides would not circularise a large fraction of these systems by the onset of Roche-lobe overflow. This makes the study and understanding of eccentric mass-transferring systems relevant for double neutron star populations.
Binary neutron stars have been observed as millisecond pulsars, gravitational-wave sources, and as the progenitors of short gamma-ray bursts and kilonovae. Massive stellar binaries that evolve into merging double neutron stars are believed to experience a common-envelope episode. During this episode, the envelope of a giant star engulfs the whole binary. The energy transferred from the orbit to the envelope by drag forces or from other energy sources can eject the envelope from the binary system, leading to a stripped short-period binary. In this paper, we use one-dimensional single stellar ev…
Near the surface of any neutron star there is a thin heat blanketing envelope that produces substantial thermal insulation of warm neutron star interiors and that relates the internal temperature of the star to its effective surface temperature. Physical processes in the blanketing envelopes are reasonably clear but the chemical composition is not. The latter circumstance complicates inferring physical parameters of matter in the stellar interiors from observations of the thermal surface radiation of the stars and urges one to elaborate the models of blanketing envelopes. We outline physical p…
The Complete Evolution of a Neutron-Star Binary through a Common Envelope Phase Using 1D Hydrodynamic Simulations
超过四十年的研究表明，共同包层阶段，即演化恒星在膨胀时吞没其伴星的阶段，是形成短周期致密天体双星系统的关键演化阶段，例如合并的双致密天体、X射线双星和激变变星。在这项工作中，我们采用一维流体动力学恒星演化程序MESA，模拟了1.4 M $_{\odot}$中子星（NS）在12 $M_{\odot}$红超巨星包层内的内旋。我们自洽地计算NS所经历的阻力以及NS螺旋进入时对膨胀包络的反作用。几乎所有的氢包层都逃逸出来，膨胀到大半径（$\sim$ 10 $^2$ AU），在那里它形成了一个光学厚度的包层，温度低到足以形成尘埃。我们模拟NS轨道，直到只有0.8 M $_{\odot}$的氢包层仍然围绕巨星的核心。我们的研究结果表明，内旋将继续，直到另一个$\approx$ 0.3 M $_{\odot}$被删除，在这一点上，剩余的信封将收回。在分离时，很可能会出现一个动态稳定的质量转移到NS吸积体上的阶段，这可能是一个可以观察到的超亮X射线源。由此产生的双星，包括一个分离的2.6 M $_{\odot}$氦星和一个NS与3.3- 5.7 R $_{\odot}$的分离，预计将演变成一个合并的双中子星，类似于最近由LIGO/室女座探测到的。对于我们选择的二元参数组合，我们估计的最终分离（包括稳定传质阶段）表明$\approx$ 5具有非常高的$α_{\rm CE}$等效效率。
Modeling the evolution of progenitors of gravitational-wave merger events in binary stars faces two major uncertainties: the common-envelope phase and supernova kicks. These two processes are critical for the final orbital configuration of double compact-object systems with neutron stars and black holes. Predictive one-dimensional models of common-envelope interaction are lacking and multidimensional simulations are challenged by the vast range of relevant spatial and temporal scales. Here, we present three-dimensional hydrodynamic simulations of the common-envelope interaction of an initially…
A binary neutron star merger has been observed in a multi-messenger detection of gravitational wave (GW) and electromagnetic (EM) radiation. Binary neutron stars that merge within a Hubble time, as well as many other compact binaries, are expected to form via common envelope evolution. Yet five decades of research on common envelope evolution have not yet resulted in a satisfactory understanding of the multi-spatial multi-timescale evolution for the systems that lead to compact binaries. In this paper, we report on the first successful simulations of common envelope ejection leading to binary …
Effect of Neutron Star Jets on Common Envelope Evolution
National Institute of Science Education and Research（印度科学教育与研究国家研究所）；Homi Bhabha National Institute（霍米·巴巴国家研究所）；University of Rochester（罗切斯特大学）；Center for Integrated Research Computing, University of Rochester（罗切斯特大学综合计算研究中心）；National Technical Institute for the Deaf, Rochester Institute of Technology（纽约理工学院聋人国家技术学院）；Center for Computational Relativity and Gravitation, Rochester Institute of Technology（纽约理工学院计算相对论与引力中心）
Common-envelope evolution is a stage in binary system evolution in which a giant star engulfs a companion. The standard energy formalism is an analytical framework to estimate the amount of energy transferred from the companion's shrinking orbit into the envelope of the star that engulfed it. We show analytically that this energy transfer is larger than predicted by the standard formalism. As the orbit of the companion shrinks, the mass it encloses becomes smaller, and the companion is less bound than if the enclosed mass had remained constant. Therefore, more energy must be transferred to the…
Asymmetric shapes and evidence for binary central stars suggest a common-envelope origin for many bipolar planetary nebulae. The bipolar components of the nebulae are observed to expand faster than the rest and the more slowly expanding material has been associated with the bulk of the envelope ejected during the common-envelope phase of a stellar binary system. Common-envelope evolution in general remains one of the biggest uncertainties in binary star evolution and the origin of the fast outflow has not been explained satisfactorily. We perform three-dimensional magnetohydrodynamic simulatio…
EPISODE IV: Ice Inventory in the Envelope of EC 53
Korea Astronomy and Space Science Institute（韩国天文与空间科学研究所）；Seoul National University（首尔大学）；Research Institute of Basic Sciences, Seoul National University（首尔大学基础科学研究院）；RIKEN Pioneering Research Institute（理化学研究所先导研究院）；University of Tokyo（东京大学）；Peking University（北京大学）
The detection of the unusually heavy binary neutron star merger GW190425 marked a stark contrast to the mass distribution from known Galactic pulsars in double neutron star binaries and gravitational-wave source GW170817. We suggest here a formation channel for heavy binary neutron stars and light black hole - neutron star binaries in which massive helium stars, which had their hydrogen envelope removed during a common envelope phase, remain compact and avoid mass transfer onto the neutron star companion, possibly avoiding pulsar recycling. We present three-dimensional simulations of the super…
Tidal dissipation due to turbulent viscosity in the convective regions of giant stars plays an important role in shaping the orbits of pre-common envelope systems. Such systems are possible sources of transients and close compact binary systems that will eventually merge and produce detectable gravitational wave signals. Most previous studies of the onset of common envelope episodes have focused on circular orbits and synchronously rotating donor stars under the assumption that tidal dissipation can quickly spin up the primary and circularize the orbit before the binary reaches Roche-lobe over…
The progenitors of compact-object binaries: impact of metallicity, common envelope and natal kicks
LIGO-Virgo合作（LVC）已经报道了六个引力波事件，其中五个与黑洞双星（BHB）合并有关，一个与双中子星（DNS）合并有关，而黑洞-中子星（BHNS）双星的合并仍然缺失。我们调查的祖先的双重紧凑的对象二进制与我们的人口合成代码MOBSE。MOBSE包括恒星风造成的质量损失的高级处方（取决于金属丰度和爱丁顿比），以及核心坍缩、电子俘获和（脉动）对不稳定超新星的形式主义。我们研究了祖先的金属丰度，共同包络参数$α$和出生踢的DNSs，BHNSs和BHBs的属性的影响。我们发现，中子星（NS）的质量范围从1.1到2.0 M $_\odot$，与轻NS的偏好，而在合并BHNS NS的NS大多有大的质量（$1.3-2.0$ M $_\odot$）。合并BHN中的BH优先为低质量（$5-15$ M $_\odot$）。合并BHB中的BH质量强烈依赖于祖细胞的金属性，并且从$\sim{}5$跨越到$\sim{}45$ M $_\odot$。从我们的模拟中得出的BHNS和BHB的本地合并率密度与LVC在我们所有的模拟中报告的值是一致的。与此相反，本地合并率密度的DNS匹配的值推断出的LVC只有当低出生踢假定。这一结果为本征踢和DNS形成的复杂谜题增添了另一个部分。
Population synthesis of low-mass binaries with wind-accreting neutron stars
Sternberg Astronomical Institute, Lomonosov Moscow State University（莫斯科国立大学列昂诺夫天文研究所）；Department of Physics, Lomonosov Moscow State University（莫斯科国立大学物理系）
We perform 3D hydrodynamical simulations of new-born neutron stars (NSs) colliding with main-sequence binary companions after supernova explosions. Based on those hydrodynamical models, we construct a semi-analytical formula that describes the drag force inside stars with steep density gradients. We then compute the outcome of NS--companion collisions over a wide range of parameters using the semi-analytical formula. Depending on the direction and magnitude of the natal kick, we find that the collision may lead to various outcomes. For relatively fast kicks and high impact parameters, the NS m…
The cooling of the Cassiopeia A neutron star as a probe of a triplet neutron pairing in the core
仙后座A中子星（Cas A NS）的快速冷却可以解释为在恒星的核心中中子超流的开始触发，导致中子库珀对破裂和形成（PBF）的中微子发射增强。这为探测堆芯中的中子凝聚物提供了独特的可能性。使用一致的中子星内核和地壳的状态方程和成分，我探讨了这种解释的敏感性的三重态超流凝析油的相态。通过在预期的中子星质量和包层组成范围内模拟冷却，发现Cas A NS的快速冷却不能用传统的含$m_{j}=0$的$^3$ P $_2$凝聚体中的PBF过程来解释。
Neutron Star Mass-Radius Constraints for EXO 0748$-$676 from 2008-2025 Quiescent X-ray Spectra
Xiamen University（厦门大学）；Yunnan Observatories, Chinese Academy of Sciences (CAS)（中国科学院云南天文台）；Key Laboratory for the Structure and Evolution of Celestial Objects, CAS（中国科学院天体结构与演化重点实验室）
