The first neutron star binary merger detected in gravitational waves, GW170817 and the subsequent detection of its emission across the electromagnetic spectrum showed that these systems are viable progenitors of short $γ$-ray bursts (sGRB). The afterglow signal of GW170817 has been found to be consistent with a structured GRB jet seen off-axis, requiring significant amounts of relativistic material at large angles. This trait can be attributed to the interaction of the relativistic jet with the external wind medium. Here we perform numerical simulations of relativistic jets interacting with realistic wind environments in order to explore how the properties of the wind and central engine affect the structure of successful jets. We find that the angular energy distribution of the jet depends primarily on the ratio between the lifetime of the jet and the time it takes the merger remnant to collapse. We make use of these simulations to constrain the time it took for the merger remnant in GW170817 to collapse into a black hole based on the angular structure of the jet as inferred from afterglow observations.
We conclude that the lifetime of the merger remnant in GW170817 was $\approx 1-1.7$s, which, after collapse, triggered the formation of the jet.
Both the core collapse of rotating massive stars, and the coalescence of neutron star (NS) binaries, result in the formation of a hot, differentially rotating NS remnant. The timescales over which differential rotation is removed by internal angular-momentum transport processes (`viscosity') has key implications for the remnant's long-term stability and the NS equation-of-state (EOS). Guided by a non-rotating model of a cooling proto-NS, we estimate the dominant sources of viscosity using an externally imposed angular velocity profile $Ω(r)$. Although the magnetorotational instability provides…
Binary population synthesis (BPS) employs prescriptions to predict final fates, explosion or implosion, and remnant masses based on one or two stellar parameters at the evolutionary cutoff imposed by the code, usually at or near central carbon ignition. In doing this, BPS disregards the integral role late-stage evolution plays in determining the final fate, remnant type, and remnant mass within the neutrino-driven explosion paradigm. To highlight differences between a popular prescription which relies only on the core and final stellar mass and emerging methods which rely on a star's presupern…
I identify a point-symmetric structure in recently published VLT/MUSE velocity maps of different elements in a plane along the line of sight at the center of the supernova remnant SNR 0540-69.3, and argue that jittering jets that exploded this core collapse supernova shaped this point-symmetric structure. The four pairs of two opposite clumps that compose this point symmetric structure suggest that two to four pairs of jittering jets shaped the inner ejecta in this plane. In addition, intensity images of several spectral lines reveal a faint strip (the main jet-axis) that is part of this plane…
Recent progress in the three-dimensional modeling of supernovae (SN) has shown the importance of asymmetries for the explosion. This calls for a reconsideration of the modeling of the subsequent phase, the supernova remnant (SNR), which has commonly relied on simplified ejecta models. In this paper we bridge SN and SNR studies by using the output of a SN simulation as the input of a SNR simulation carried on until 500~yr. We consider the case of a thermonuclear explosion of a carbon-oxygen white dwarf star as a model for a Type Ia SN; specifically we use the N100 delayed detonation model of Se…
The remnant of neutron star mergers is dense in neutrinos. By employing inputs from one hydrodynamical simulation of a binary neutron star merger remnant with a black hole of $3\ M_\odot$ in the center, dimensionless spin parameter $0.8$ and an accretion torus of $0.3\ M_\odot$, the neutrino emission properties are investigated as the merger remnant evolves. Initially, the local number density of $\barν_e$ is larger than that of $ν_e$ everywhere above the remnant. Then, as the torus approaches self-regulated equilibrium, the local abundance of neutrinos overcomes that of antineutrinos in a fun…
We construct evolutionary models of the remnant of the merger of two carbon-oxygen (CO) core white dwarfs (WDs). With total masses in the range $1-2 {\rm M_\odot}$, these remnants may either leave behind a single massive WD or undergo a merger-induced collapse to a neutron star (NS). On the way to their final fate, these objects generally experience a $\sim 10$ kyr luminous giant phase, which may be extended if sufficient helium remains to set up a stable shell-burning configuration. The uncertain, but likely significant, mass loss rate during this phase influences the final remnant mass and f…
3D simulations of young core-collapse supernova remnants undergoing efficient particle acceleration
在我们的银河系内，超新星遗迹被认为是宇宙射线的主要来源。然而，重要的问题仍然是关于强子和轻子成分的份额，以及超新星能量的一部分被引导到这些成分中。我们解决这样的问题，通过数值模拟的手段相结合的冲击波的动力学处理与粒子加速。执行3D模拟使我们能够生成热发射和非热发射的合成投影图和光谱，可以与多波长观测（无线电，X射线和伽马射线）进行比较。超新星有不同的类型，虽然它们的能量收支是相同的，但它们的残余物有不同的性质，因此可能以不同的方式对银河宇宙射线池做出贡献。我们的第一个模拟集中在热核超新星，像第谷的SNR，通常发生在一个基本上不受干扰的介质。在这里，我们提出了我们的核心坍缩超新星的三维模拟，如Cas A SNR，发生在一个更复杂的介质轴承的祖先恒星的风的印记。
(abridged) We investigate the quark deconfinement phase transition in the context of binary neutron star (BNS) mergers. We employ a new finite-temperature composition-dependent equation of state (EOS) with a first order phase transition between hadrons and deconfined quarks to perform numerical relativity simulations of BNS mergers. The softening of the EOS due to the phase transition causes the merger remnants to be more compact and to collapse to a black hole (BH) at earlier times. The phase transition is imprinted on the postmerger gravitational wave (GW) signal duration, amplitude, and pea…
Late-time Evolution of Composite Supernova Remnants: Deep Chandra Observations and Hydrodynamical Modeling of a Crushed Pulsar Wind Nebula in SNR G327.1-1.1
Although multidimensional simulations have investigated the processes of double WD mergers, post-merger evolution only focused on the carbon-oxygen (CO) WD or helium (He) WD merger remnants. In this work, we investigate for the first time the evolution of the remnants stemmed from the merger of oxygen-neon (ONe) WDs with CO WDs. Our simulation results indicate that the merger remnants can evolve to hydrogen- and helium-deficient giants with maximum radius of about 300Rsun. Our models show evidence that merger remnants more massive than 1.95Msun can ignite Ne before significant mass-loss ensues…
Mergers of compact binaries containing two neutron stars (NS-NS), or a neutron star and a stellar-mass black hole (NS-BH), are likely progenitors of short-duration gamma ray bursts (SGRBs). A fraction >20% of SGRBs are followed by temporally-extended (>~ minute-long), variable X-ray emission, attributed to ongoing activity of the central engine. One source of late-time engine activity is fall-back accretion of bound tidal ejecta; however, observed extended emission light curves do not track the naively-anticipated, uninterrupted ~t^{-5/3} power-law decay, instead showing a lull or gap in emiss…
The contribution of young core-collapse supernova remnants to the X-ray emission near quiescent supermassive black holes
在超大质量黑洞（SMBH）附近经常发现可观的恒星形成，因此也有大量的大质量恒星。因此，在这些区域也应该预期有核心坍缩的超新星。在本文中，我们考虑的观测后果预测的命运超新星遗迹（SNRs）的影响范围内的静止SMBH。我们提出了这些结果的背景下，“自给自足”的核，一个模型，描述静态的核稳定状态和自给自足的环境中的SMBH吸积恒星风没有明显的流入的材料超出了影响范围。这些区域具有与SMBH的质量成比例的性质，例如气体密度。使用的X射线寿命的SNRs起源于影响范围的预测，我们作出的核心崩溃SNRs在给定的时间存在的数量的估计。随着对信噪比的寿命及其与年轻恒星的关联的了解，我们预测了一些核心坍缩的信噪比，从银河系（4.3 x 10^6 Msun）SMBH周围的~1增长到最高质量（10^10 Msun）SMBH周围的~100。年轻的SNR的存在将放大附近的静态SMBHs的X射线发射，我们表明，总的核心崩溃SNR发射有可能影响软X射线搜索非常低的光度SMBHs。我们的SNR寿命估计也使我们能够预测这些地区的恒星形成率。假设大质量恒星处于稳定的补充状态，我们估计银河系SMBH周围的恒星形成率密度为2 x 10^-4 Msun/yr/pc^2，由于SMBH对质量的依赖性较弱，其他SMBH周围的恒星形成率密度也类似。这一数值与目前的观测结果一致。
The gravitational wave data of GW170817 favor the equation of state (EoS) models that predict compact neutron stars (NSs), consistent with the radius constraints from X-ray observations. Motivated by such a remarkable progress, we examine the fate of the remnants formed in NS mergers and focus on the roles of the angular momentum and the mass distribution of the binary NSs. In the mass shedding limit (for which the dimensionless angular momentum equals to the Keplerian value, i.e., $j=j_{\rm Kep}$), the adopted { seven EoS models, except H4 and ALF2,} yield supramassive NSs in more than half o…
The final fate of gravitational collapse of massive stars has been a subject of interest for a long time since such a collapse may lead to black holes and naked singularities alike. Since, the formation of naked singularities is forbidden by the cosmic censorship conjecture, exploring their observational differences from black holes may be a possible avenue to search for these exotic objects. The simplest possible naked singularity spacetime emerges from the Einstein massless scalar field theory with the advantage that it smoothly translates to the Schwarzschild solution by the variation of th…
Ultralight bosons are a proposed solution to outstanding problems in cosmology and particle physics: they provide a dark-matter candidate while potentially explaining the strong charge-parity problem. If they exist, ultralight bosons can interact with black holes through the superradiant instability. In this work we explore the consequences of this instability on the evolution of hierarchical black holes within dense stellar clusters. By reducing the spin of individual black holes, superradiance reduce the recoil velocity of merging binary black holes, which, in turn, increases the retention f…
Understanding astrophysical phenomena involving compact objects requires an insight about the engine behind core-collapse supernovae (SNe) and the fate of the stellar collapse of massive stars. In particular, this insight is crucial in developing an understanding of the origin and formation channels of detected population of BH-BH, BH-NS and NS-NS mergers. To gain this understanding, we must tie our current knowledge of pre-SN stars properties and their potential explosions to the final NS or BH mass distribution. The timescale of convection growth may have a large effect on the strength of SN…
We study the evolution and final outcome of long-lived (${\approx}10^5$ years) remnants from the merger of a He white dwarf (WD) with a more massive C/O or O/Ne WD. Using Modules for Experiments in Stellar Astrophysics ($\texttt{MESA}$), we show that these remnants have a red giant configuration supported by steady helium burning, adding mass to the WD core until it reaches $M_{\rm core}\approx 1.12-1.20 M_\odot$. At that point, the base of the surface convection zone extends into the burning layer, mixing the helium burning products (primarily carbon and magnesium) throughout the convective e…
Merger remnant and eccentricity dynamics surrogates for eccentric nonspinning black hole binaries
University of Massachusetts, Dartmouth（麻省大学达特茅斯分校）；Max Planck Institute for Gravitational Physics(Albert Einstein Institute)（马克斯·普朗克引力物理研究所（爱因斯坦研究所））；Cornell University（康奈尔大学）；University of California Santa Barbara（加州大学圣塔芭芭拉分校）；California State University Fullerton（加州州立大学富勒顿分校）；Northwestern University（西北大学）
LBVs are massive evolved stars that suffer sporadic and violent mass-loss events. They have been proposed as the progenitors of some core-collapse SNe, but this idea is still debated due to the lack of direct evidence. Since SNRs can carry in their morphology the fingerprints of the progenitor stars as well as of the inhomogeneous CSM sculpted by the progenitors, the study of SNRs from LBVs could help to place core-collapse SNe in context with the evolution of massive stars. We investigate the physical, chemical and morphological properties of the remnants of SNe originating from LBVs, in orde…
The QCD axion is a hypothetical particle motivated by the Strong CP problem of particle physics. One of the primary ways in which its existence can be inferred is via its function as an additional cooling channel in stars, with some of the strongest constraints coming from the supernova observation SN1987A. Multimessenger observations of binary neutron star mergers (such as those of GW170817, AT2017gfo, and GRB170817A) may provide another scenario in which such constraints could be obtained. In particular, the axion could potentially alter the lifetime, the ejection of material, and the emitte…
A Burst in a Wind Bubble and the Impact on Baryonic Ejecta: High-Energy Gamma-Ray Flashes and Afterglows from Fast Radio Bursts and Pulsar-Driven Supernova Remnants
We identify an observable imprint of a first-order hadron-quark phase transition at supranuclear densities on the gravitational-wave (GW) emission of neutron star mergers. Specifically, we show that the dominant postmerger GW frequency f_peak may exhibit a significant deviation from an empirical relation between f_peak and the tidal deformability if a strong first-order phase transition leads to the formation of a gravitationally stable extended quark matter core in the postmerger remnant. A comparison of the GW signatures from a large, representative sample of microphysical, purely hadronic e…
