Massive stars end their life in an explosion event with kinetic energies of the order 1 Bethe. Immediately after the explosion has been launched, a region of low density and high entropy forms behind the ejecta which is continuously subject to neutrino heating. The neutrinos emitted from the remnant at the center, the protoneutron star (PNS), heat the material above the PNS surface. This heat is partly converted into kinetic energy and the material accelerates to an outflow that is known as the neutrino driven wind. For the first time, we simulate the collapse, bounce, explosion and the neutrino driven wind phases consistently over more than 20 seconds. Our numerical model is based on spherically symmetric general relativistic radiation hydrodynamics using spectral three flavor Boltzmann neutrino transport. In simulations where no explosions are obtained naturally, we model neutrino driven explosions for low and intermediate mass Fe-core progenitor stars by enhancing the charged current reaction rates. In the case of a special progenitor star, the O-Ne-Mg-core, the explosion in spherical symmetry was obtained without enhanced opacities. The post explosion evolution is in qualitative agreement with static steady-state and parametrized dynamic models of the neutrino driven wind. On the other hand, we find generally smaller neutrino luminosities and mean neutrino energies as well as a different evolutionary behavior of the neutrino luminosities and mean neutrino energies. The neutrino driven wind is proton-rich for more than 10 seconds and the contraction of the PNS differs from the assumptions made for the conditions at the inner boundary in previous neutrino driven wind studies. Despite the moderately large entropies per baryon of about 100 and the fast expansion timescale, the conditions found in our model are unlikely to favor...
We investigate the protoneutron star (PNS) convection using our newly developed general relativistic Boltzmann neutrino radiation-hydrodynamics code. This is a pilot study for more comprehensive investigations later. As such, we take a snapshot of a PNS at 2.3 seconds after bounce from a 1D PNS cooling calculation and run our simulation for $\sim160\,\mathrm{ms}$ in 2D under axisymmetry. The original PNS cooling calculation neglected convection entirely and the initial condition is linearly unstable to convection. We find in our 2D simulation that convection is instigated there indeed and expa…
Details of the explosion mechanism of core-collapse supernovae (CCSNe) are not yet fully understood. There is now an increasing number of successful examples of reproducing explosions in the first-principles simulations, which have shown a slow increase of explosion energy. However, it was recently pointed out that the growth rates of the explosion energy of these simulations are insufficient to produce enough $^{56}$Ni mass to account for observations. We refer to this issue as the `nickel mass problem' (Ni problem, hereafter) in this paper. The neutrino-driven wind is suggested as one of the…
To obtain the eigenfrequencies of a protoneutron star (PNS) in the postbounce phase of core-collapse supernovae (CCSNe), we perform a linear perturbation analysis of the angle-averaged PNS profiles using results from a general relativistic CCSN simulation of a $15 M_{\odot}$ star. In this work, we investigate how the choice of the outer boundary condition could affect the PNS oscillation modes in the linear analysis. By changing the density at the outer boundary of the PNS surface in a parametric manner, we show that the eigenfrequencies strongly depend on the surface density. By comparing wit…
We examine the protoneutron star (PNS) stability in this study by solving the radial oscillation equations. For this purpose, we adopt the numerical results of massive PNS toward the black hole formation obtained by spherically symmetric numerical simulations for core-collapse supernova with general relativistic neutrino-radiation hydrodynamics. We find that the PNSs are basically stable in their evolution against the radial perturbations, while the PNS finally becomes unstable before the apparent horizon appears inside the PNS. We also examine the gravitational wave frequencies from PNS with …
用二维中微子辐射流体动力学程序模拟了一颗11.2 $M_{\odot}$星的引力坍缩、反弹和铁芯爆炸。爆炸是由中微子加热驱动的，辅之以多维流体动力学效应，如对流。爆炸阶段之后，我们继续模拟的质子中子星的热演化的$\sim$ 70 s时，地壳的中子星形成使用一维模拟。发现地壳在高密度区（$ρ\sim10^{14}$ g cm $^{-3}$）形成，并由内向外推进。这是第一个自洽的模拟，成功地遵循从坍缩阶段的质子中子星冷却阶段的多维流体动力学模拟的基础上。
We examine the frequencies of the fundamental ($f$-) and the gravity ($g_i$-) mode in gravitational waves from accreting protoneutron stars (PNSs) toward black hole formation. For this purpose, we analyze numerical results of gravitational collapse of massive stars for two different progenitors with three equations of state. We adopt profiles of central objects obtained from the numerical simulations by solving general relativistic neutrino-radiation hydrodynamics under the spherical symmetry. Using a series of snapshots as a static configuration at each time step, we solve the eigenvalue prob…
The wind driven by the intense neutrino emission from a protoneutron star (PNS) is an important site for producing nuclei heavier than the Fe group. Because of certain features in the neutrino angular distributions, the so-called fast flavor oscillations may occur very close to the PNS surface, effectively resetting the neutrino luminosities and energy spectra that drive the wind. Using the unoscillated neutrino emission characteristics from two core-collapse supernova simulations representative of relevant progenitors at the lower and higher mass end, we study the potential effects of fast fl…
Blueshifted absorption lines are seen in high inclination black hole binary systems in their disc dominated states, showing these power an equatorial disc wind. While some contribution from magnetic winds remain a possibility, thermal and thermal-radiative winds are expected to be present. We show results from radiation hydrodynamic simulations which show that the additional radiation force from atomic features (bound-free and lines) are important along with electron scattering. Together, these increase the wind velocity at high inclinations, so that they quantitatively match the observations …
Identification and characterization of a rapidly increasing number of pulsar wind nebulae is, and will continue to be, a challenge of high-energy gamma-ray astrophysics. Given that such systems constitute -- by far -- the most numerous expected population in the TeV regime, such characterization is important not only to learn about the sources per se from an individual and population perspective, but also to be able to connect them with observations at other frequencies, especially in radio and X-rays. Also, we need to remove the emission from nebulae in highly confused regions of the sky for …
We solve the two-dimensional hydrodynamic equations of hot accretion flow in the presence of the thermal conduction. The flow is assumed to be in steady-state and axisymmetric, and self-similar approximation is adopted in the radial direction. In this hydrodynamic study, we consider the viscous stress tensor to mimic the effects of the magnetorotational instability for driving angular momentum. We impose the physical boundary conditions at both the rotation axis and the equatorial plane and obtain the solutions in the full $ r-θ$ space. We have found that thermal conduction is indispensable te…
A protoneutron star produced in a core-collapse supernova (CCSN) drives a wind by its intense neutrino emission. We implement active-sterile neutrino oscillations in a steady-state model of this neutrino-driven wind to study their effects on the dynamics and nucleosynthesis of the wind in a self-consistent manner. Using vacuum mixing parameters indicated by some experiments for a sterile $ν_s$ of $\sim 1$ eV in mass, we observe interesting features of oscillations due to various feedback. For the higher $ν_s$ mass values, we find that oscillations can reduce the mass loss rate and the wind vel…
High-mass microquasar jets, produced in an accreting compact object in orbit around a massive star, must cross a region filled with stellar wind. The combined effects of the wind and orbital motion can strongly affect the jet properties on binary scales and beyond. The study of such effects can shed light on how high-mass microquasar jets propagate and terminate in the interstellar medium. We study for the first time, using relativistic hydrodynamical simulations, the combined impact of the stellar wind and orbital motion on the properties of high-mass microquasar jets on binary scales and bey…
Essentially all low-mass X-ray binaries (LMXBs) in the soft state appear to drive powerful equatorial disc winds. A simple mechanism for driving such outflows involves X-ray heating of the top of the disc atmosphere to the Compton temperature. Beyond the Compton radius, the thermal speed exceeds the escape velocity, and mass loss is inevitable. Here, we present the first coupled radiation-hydrodynamic simulation of such thermally-driven disc winds. The main advance over previous modelling efforts is that the frequency-dependent attenuation of the irradiating SED is taken into account. We can t…
Numerical simulations of black hole hot accretion flows have shown the existence of strong wind. Those works focus only on the region close to black hole thus it is unknown whether or where the wind production stops at large radii. To address this question, Bu et al. (2016) have performed hydrodynamic (HD) simulations by taking into account the gravitational potential of both the black hole and the nuclear star clusters. The latter is assumed to be $\propto σ^2 \ln(r)$, with $σ$ being the velocity dispersion of stars and $r$ be the distance from the center of the galaxy. It was found that when…
Previous works show strong winds exist in hot accretion flows around black holes. Those works focus only on the region close to the black hole thus it is unknown whether or where the wind production stops at large radii. In this paper, we investigate this problem by hydrodynamical simulations. We take into account gravities of both the black hole and the nuclear star clusters. For the latter, we assume that the velocity dispersion of stars is a constant and its gravitational potential $\propto σ^2 \ln (r)$, where $σ$ is the velocity dispersion of stars and $r$ is the distance from the center o…
We present new 1D (spherical) and 2D (axisymmetric) simulations of electron-capture (EC) and low-mass iron-core-collapse supernovae (SN). We consider six progenitor models: the ECSN progenitor from Nomoto (1984, 1987); two ECSN-like low-mass low-metallicity iron core progenitors from Heger (private communication); and the 9-, 10-, and 11-$M_\odot$ (zero-age main sequence) progenitors from Sukhbold et al. (2016). We confirm that the ECSN and ESCN-like progenitors explode easily even in 1D with explosion energies of up to a 0.15 Bethes ($1 {\rm B} \equiv 10^{51}\ {\rm erg}$), and are a viable me…
Many astrophysical sources, e.g., cataclysmic variables, X-ray binaries, active galactic nuclei, exhibit a wind outflow, when they reveal a multicolor blackbody spectrum, hence harboring a geometrically thin Keplerian accretion disk. Unlike an advective disk, in the thin disk, the physical environment, like, emission line, external heating, is expected to play a key role to drive the wind outflow. We show the wind outflow in a thin disk attributing a disk irradiation effect, probably from the inner to outer disks. We solve the set of steady, axisymmetric disk model equations in cylindrical coo…
Winds from black hole accretion flows are ubiquitous. Previous works mainly focus on the launching of wind in the accretion flow scale. It still remains unclear how far the winds can propagate outward and what is their large-scale dynamics. As the first paper of this series, we study the large-scale dynamics of thermal wind beyond accretion scales via analytical and numerical methods. Boundary conditions, which are crucial to our problem, are analyzed and presented based on the small-scale simulations combined with observations of winds. Both black hole and galaxy potential are taken into acco…
Multi-dimensional modelling of X-ray spectra for AGN accretion-disk outflows III: application to a hydrodynamical simulation
我们进行多维辐射转移模拟计算光谱的流体动力学模拟的线驱动吸积盘风从活动星系核。合成光谱证实了参数化模型的预期，即盘风可以留下各种各样的光谱特征，包括窄吸收线，宽发射线和康普顿峰。这些特征的形成是复杂的，其贡献来自流体动力学模拟中存在的许多不同结构。特别是，光谱特征的形状都是由气体在一个成功推出的外流，并在复杂的流动中，材料被解除出磁盘平面，但最终回落。我们还证实，强Fe K α线可以开发一个弱的，红色的斜线翼作为康普顿散射的结果在外流。此外，我们还证明了X射线辐射在气流中的散射和再处理在光谱形成和确定风中的电离条件方面具有关键作用。我们发现，散射辐射是相当有效的电离气体，这是从中心源的直接辐射屏蔽。这种效应可能使成功发射大规模盘风更具挑战性，应在未来的风模拟中加以考虑。
Hydrodynamical simulation of wind production from hot accretion flows in tidal disruption events
National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；Shanghai Key Lab for Astrophysics, Shanghai Normal University（上海师范大学天体物理上海市重点实验室）；Department of Physics, Chongqing University（重庆大学物理学院）；School of Physics and Astronomy, Beijing Normal University（北京师范大学物理与天文学院）；School of Astronomy and Space Science, University of Chinese Academy of Sciences（中国科学院大学天文与空间科学学院）
We present neutrino-transport hydrodynamic simulations of electron-capture supernovae (ECSNe) in \texttt{FLASH} with new two-dimensional (2D) collapsing progenitor models. These progenitor models feature the 2D modelling of oxygen-flame propagation until the onset of core collapse. We perform axisymmetric simulations with 6 progenitor models that, at the time of collapse, span a range of propagating flame front radii. For comparison, we also perform a simulation with the same setup using the canonical, spherically-symmetrical progenitor model n8.8. We found that the variations in the progenito…
We present Athena++ grid-based, hydrodynamic simulations of accretion onto Sagittarius A* via the stellar winds of the $\sim 30$ Wolf-Rayet stars within the central parsec of the galactic center. These simulations span $\sim$ 4 orders of magnitude in radius, reaching all the way down to 300 gravitational radii of the black hole, $\sim 32$ times further in than in previous work. We reproduce reasonably well the diffuse thermal X-ray emission observed by Chandra in the central parsec. The resulting accretion flow at small radii is a superposition of two components: 1) a moderately unbound, sub-K…
3D Moving-mesh Hydrodynamical Simulations of Wind/Jet Driven Ultraluminous X-ray Source Bubbles
Center for Computational Sciences, University of Tsukuba（筑波大学计算科学中心）；Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；Tsinghua University（清华大学）
CONTEXT: Vela X-1, a prototypical high mass X-ray binary (HMXB), hosts a neutron star (NS) in a close orbit around an early-B supergiant donor star. Accretion of the donor star's wind onto the NS powers its strong X-ray luminosity. To understand the physics of HMXBs, detailed knowledge about the donor star winds is required. AIMS: To gain a realistic picture of the donor star in Vela X-1, we constructed a hydrodynamically consistent atmosphere model describing the wind stratification while properly reproducing the observed donor spectrum. To investigate how X-ray illumination affects the stell…
Using the Boltzmann-radiation-hydrodynamics code, which solves the Boltzmann equation for neutrino transport, we present the results of the simulations with the nuclear equations of state (EOSs) of Lattimer and Swesty (LS) and Furusawa and Shen (FS). We extend the simulation time of the LS model and conduct thorough investigations, though our previous paper briefly reported some of the results. Only the LS model shows the shock revival. This seems to originate from the nuclear composition: the different nuclear composition results in the different energy loss by photodissociation and hence the…
Classical Wolf Rayet (WR) stars are direct supernova progenitors undergoing vigorous mass-loss. Understanding the dense and fast outflows of such WR stars is thus crucial for understanding advanced stages of stellar evolution, the dynamical feedback of massive stars on their environments, and characterizing the distribution of black hole masses. In this paper, we develop first time-dependent, multi-dimensional, radiation-hydrodynamical models of the extended optically thick atmospheres and wind outflows of hydrogen-free classical WR stars. A flux limiting radiation hydrodynamics approach is us…
Ultraviolet (UV) line driven winds may be an important part of the active galactic nucleus (AGN) feedback process, but understanding their impact is hindered by the complex nature of the radiation hydrodynamics. Instead, we have taken the approach pioneered by Risaliti & Elvis, calculating only ballistic trajectories from radiation forces and gravity, but neglecting gas pressure. We have completely re-written their QWIND code using more robust algorithms, and can now quickly model the acceleration phase of these winds for any AGN spectral energy distribution spanning UV and X-ray wavebands. We…
Growth of the black holes (BHs) from the seeds to supermassive BHs (SMBHs, $\sim\!10^9\,M_\odot$) is not understood, but the mass accretion must have played an important role. We performed two-dimensional radiation hydrodynamics simulations of line-driven disc winds considering the metallicity dependence in a wide range of the BH mass, and investigated the reduction of the mass accretion rate due to the wind mass loss. Our results show that denser and faster disc winds appear at higher metallicities and larger BH masses. The accretion rate is suppressed to $\sim\! 0.4$--$0.6$ times the mass su…
We use multi-frequency radiation hydrodynamics (rad-HD) to simulate radiative acceleration of a spherically symmetric stellar wind. We demonstrate the rad-HD capabilities of Athena++ for a series of test problems with multi-group radiation transfer. We then model the radiative transfer of a single spectral line through a spherically symmetric, isothermal, "CAK"-type line driven wind. We find that correctly accounting for the Doppler shift of the absorbed radiation, the force is well described by the analytic Sobolev line transfer in the supersonic parts of the solution where the flow is statio…
Radiation-ionization hydrodynamic simulations of AGN line-driven winds lead to transient shielding and BAL/UFO signatures
School of Physics and Astronomy, University of Southampton（南安普顿大学物理与天文学院）；Eureka Scientific Inc.（尤里卡科学公司）；Univ. Grenoble Alpes, CNRS, IPAG（格勒诺布尔阿尔卑斯大学，法国国家科学研究中心，天体物理学与行星学研究所）；Space Telescope Science Institute（太空望远镜科学研究所）；Department of Physics, Astrophysics, University of Oxford（牛津大学物理与天体物理系）；School of Mathematics and Physics, Queen’s University Belfast（贝尔法斯特女王大学数学与物理学院）
