我比较了我认为最有希望爆发核心坍缩超新星（CCSNe）的两种情况。两者都是基于负射流反馈机制（JFM）。在抖动喷流的情况下，一颗缓慢旋转的恒星的坍缩核心可以发射喷流。发射喷流的吸积盘或吸积带（一种向赤道面集中的次开普勒吸积流）是间歇性的，轴的方向不同。不稳定性，如静止吸积激波不稳定性（SASI），导致随机角动量的变化，使间歇性的吸积盘/带的形成。根据这种情况，不存在失败的CCSNe。根据固定轴假设，祖先恒星的核心必须在演化的后期阶段旋转，因此所有的CCSNe都是强相互作用双星系统的后代，最有可能是通过共同的包络演化（无论伴星是否幸存）。由于强烈的双星相互作用，围绕新生中子星形成的吸积盘的轴或多或少有一个固定的方向。在定轴假设下，新诞生的中子星周围不会形成吸积盘/吸积带，而是以失败的CCSNe告终。我还提出了这样的可能性，即抖动喷流方案适用于初始质量为8 Mo <M（ZAMS）<18 Mo的祖细胞，而固定轴方案适用于M（ZAMS）> 18 Mo。第一次，这两种情况进行了比较，以及中微子驱动的爆炸机制的某些方面。这些新的比较进一步表明，JFM在大质量恒星爆炸中起着重要作用。
英文摘要：
I compare to each other what I consider to be the two most promising scenarios to explode core-collapse supernovae (CCSNe). Both are based on the negative jet feedback mechanism (JFM). In the jittering jets scenario a collapsing core of a single slowly-rotating star can launch jets. The accretion disk or belt (a sub-Keplerian accretion flow concentrated toward the equatorial plane) that launches the jets is intermittent with varying directions of the axis. Instabilities, such as the standing accretion shock instability (SASI), lead to stochastic angular momentum variations that allow the formation of the intermittent accretion disk/belt. According to this scenario no failed CCSNe exist. According to the fixed axis scenario, the core of the progenitor star must be spun up during its late evolutionary phases, and hence all CCSNe are descendants of strongly interacting binary systems, most likely through a common envelope evolution (whether the companion survives or not). Due to the strong binary interaction, the axis of the accretion disk that is formed around the newly born neutron star has a more or less fixed direction. According to the fixed axis scenario, accretion disk/belt are not formed around the newly born neutron star of single stars; they rather end in failed CCSNe. I also raise the possibility that the jittering jets scenario operates for progenitors with initial mass of 8Mo<M(ZAMS)<18Mo, while the fixed axis scenario operates for M(ZAMS)>18Mo. For the first time these two scenarios are compared to each other, as well as to some aspects of neutrino-driven explosion mechanism. These new comparisons further suggest that the JFM plays a major role in exploding massive stars.
We evolve stellar models with zero-age main sequence (ZAMS) mass of $M_{\rm ZAMS} \gtrsim 18 M_\odot$ under the assumption that they experience an enhanced mass-loss rate when crossing the instability strip at high luminosities and conclude that most of them end as type Ibc supernovae (SNe Ibc) or dust-obscured SNe II. We explore what level of enhanced mass-loss rate during the instability strip would be necessary to explain the `red supergiant (RSG) problem'. This problem refers to the dearth of observed core-collapse supernovae progenitors with $M_{\rm ZAMS} \gtrsim 18 M_\odot$. Namely, we e…
The joint observation of core-collapse supernovae with gamma-ray bursts shows that jets can be launched in the aftermath of stellar core collapse, likely by a newly formed black hole that accretes matter from the star. Such gamma-ray bursts have only been observed accompanying Type Ibc supernovae, indicating a stellar progenitor that lost its Hydrogen envelope before collapse. According to recent hypothesis it is possible that jets are launched in core-collapse events even when the progenitors still retain their Hydrogen envelopes, however, such jets are not able to burrow through the star and…
IceCube is a cubic kilometer neutrino detector array in the Antarctic ice that was designed to search for astrophysical, high-energy neutrinos. It has detected a diffuse flux of astrophysical neutrinos that appears to be of extragalactic origin. A possible contribution to this diffuse flux could stem from core-collapse supernovae. The high-energy neutrinos could either come from the interaction of the ejecta with a dense circumstellar medium or a jet, emanating from the star's core, that stalls in the star's envelope. Here, we will present results of a stacking analysis to search for this high…
I examine the assumption that the jets that shape the axisymmetrical morphological features of core collapse supernova (CCSN) remnants are post-kick jets, i.e., the neutron star (NS) launches these jets after the explosion and after it acquired its natal kick velocity. I find that this assumption implies that the pre-collapse cores of CCSN progenitors have sufficient angular momentum fluctuations to support jittering jets that explode the star. From the finding that the shaping-jets neither tend to be aligned with the kick velocity nor to be perpendicular to it I argue that the assumption that…
Core-collapse supernovae exploding in dense winds are favorable sites for cosmic-ray (CR) acceleration to very high energies. We present our CR-radiation-hydrodynamics simulations of the explosion of a red supergiant. We study the evolution of the shock wave during the first day following core collapse, and estimate the time at which CR acceleration can start. We then calculate the maximum CR energy at the forward shock as a function of time, and show that it may already exceed 100 TeV only a few hours after shock breakout from the surface of the star.
We present a broadband spectrum of gravitational waves from core-collapse supernovae (CCSNe) sourced by neutrino emission asymmetries for a series of full 3D simulations. The associated gravitational wave strain probes the long-term secular evolution of CCSNe and small-scale turbulent activity and provides insight into the geometry of the explosion. For non-exploding models, both the neutrino luminosity and the neutrino gravitational waveform will encode information about the spiral SASI. The neutrino memory will be detectable for a wide range of progenitor masses for a galactic event. Our res…
The design and analysis of time-domain sky surveys requires the ability to simulate accurately realistic populations of core collapse supernova (SN) events. We present a set of spectral time-series templates designed for this purpose, for both hydrogen-rich (type II, IIn, IIb) and stripped envelope (types Ib, Ic, Ic-BL) core collapse supernovae. We use photometric and spectroscopic data for 67 core collapse supernovae from the literature, and for each generate a time-series spectral template. The techniques used to build the templates are fully data-driven with no assumption of any parametric …
At the present time even the most sophisticated, multi-dimensional simulations of core-collapse supernovae do not (self-consistently) include neutrino flavor transformation. This physics is missing despite the importance of neutrinos in the core-collapse explosion paradigm. Because of this dependence, any flavor transformation that occurs in the region between the proto-neutron star and the shock could result in major effects upon the dynamics of the explosion. We present the first hydrodynamic core-collapse supernova simulation which simultaneously includes flavor transformation of the free-s…
MHD Simulations of Core Collapse Supernovae with Cosmos++
我们进行了2D，轴对称，MHD模拟与宇宙++，以研究磁旋转不稳定性（MRI）的核心崩溃超新星的增长。我们已经初始化了一个非旋转的15太阳质量的祖先，注入了差异旋转和极向磁场。用Shen状态方程、参量Ye和熵演化模拟了铁核的坍缩过程。塌缩后环境中的不稳定模式的波长预计仅为~ 200 m。为了达到高空间分辨率的要求，我们采用了铁芯塌陷和反弹后的重映射技术。MRI不稳定区域出现在赤道附近，角动量和熵向外传输。更高分辨率的重映射运行显示更有力的翻转和更强的角动量和熵的传输。我们的结果与Akiyama et al.（2003）和Obergaulinger et al.（2009）的早期工作一致。
Stripped-envelope core-collapse supernovae can be divided into two broad classes: the common Type Ib/c supernovae (SNe Ib/c), powered by the radioactive decay of $^{56}$Ni, and the rare superluminous supernovae (SLSNe), most likely powered by the spin-down of a magnetar central engine. Up to now, the intermediate regime between these two populations has remained mostly unexplored. Here, we present a comprehensive study of 40 \textit{luminous supernovae} (LSNe), SNe with peak magnitudes of $M_r = -19$ to $-20$ mag, bound by SLSNe on the bright end and by SNe Ib/c on the dim end. Spectroscopical…
I find that an ingredient that was added in a recent study to facilitate the delayed neutrino explosion mechanism of core collapse supernovae, namely, large scale perturbations in the pre-collapse core, has a larger positive influence on the jittering jets explosion mechanism. By following the specific angular momentum of the accreted mass on to the newly born neutron star, I find that the accreted mass is likely to form intermittent accretion belts and disks, although they might lack axisymmetrical structure. These accretion belts and disks are likely to launch jets, but this can be simulated…
SN 2007bi and SN 1999as are among the first superluminous supernovae discovered. SN 2007bi was suggested to be powered by the radioactive decay of a large amount (5 - 10 Msun) of 56Ni. SN 1999as has a similar spectrum to SN 2007bi. One suggested way to synthesize such a large amount of 56Ni is through energetic core-collapse supernovae from very massive progenitors. Although the synthetic light curves of extremely energetic core-collapse supernovae have been shown to be consistent with SN 2007bi, no synthetic spectra have been reported. Here, we present synthetic spectra of extremely energetic…
Convection and turbulence in core-collapse supernovae (CCSNe) are inherently three-dimensional in nature. However, 3D simulations of CCSNe are computationally demanding. Thus, it is valuable to modify simulations in spherical symmetry to incorporate 3D effects using some parametric model. In this paper, we report on the formulation and implementation of general relativistic (GR) neutrino-driven turbulent convection in the spherically symmetric core-collapse supernova code \texttt{GR1D}. This is based upon the recently proposed method of Supernova Turbulence in Reduced-dimensionality (\textit{S…
I examine recent fittings of luminous supernovae (LSNe) with extra energy sources of magnetar and helium burning and find that in about half of these LSNe the fitting parameters have some problems. In some LSNe the total energy of these two energy sources is larger than the kinetic energy of the ejecta that the fitting yields. In some others LSNe the total energy of the delayed neutrino explosion mechanism and these two extra sources combined is smaller than the kinetic energy that the fitting yields. These difficulties suggest that, like earlier claims that jets power superluminous supernovae…
Most one-dimensional core-collapse simulations fail to explode, yet multi-dimensional simulations often explode. A dominant multi-dimensional effect aiding explosion is neutrino-driven convection. We incorporate a convection model in approximate one-dimensional core-collapse supernova (CCSN) simulations. This is the 1D+ method. This convection model lowers the neutrino luminosity required for explosion by 30%, similar to the reduction observed in multi-dimensional simulations. The model is based upon the global turbulence model of Mabanta & Murphy (2018) and models the mean-field turbulent flo…
Using our new state-of-the-art core-collapse supernova (CCSN) code Fornax, we explore the dependence upon spatial resolution of the outcome and character of three-dimensional (3D) supernova simulations. For the same 19-M$_{\odot}$ progenitor star, energy and radial binning, neutrino microphysics, and nuclear equation of state, changing only the number of angular bins in the $θ$ and $ϕ$ directions, we witness that our lowest resolution 3D simulation does not explode. However, when jumping progressively up in resolution by factors of two in each angular direction on our spherical-polar grid, mod…
Novae and supernovae play a key role in many fields of Astrophysics and Cosmology. Despite their importance, an accurate description of which objects explode and why and how they explode is still lacking. One of the main characteristics of such explosions is that they are the main suppliers of newly synthesized chemical elements in the Galaxy. Since some of these isotopes are radioactive, it is possible to use the corresponding gamma-rays as a diagnostic tool of the explosion thanks to their independence on the thermal state of the debris. The drawback is the poor sensitivity of detectors in t…
A notable feature of the two standard models for thermonuclear and core-collapse supernovae is that, although these two models are fundamentally different, the respective supernova types have quite similar rates and appearances. For instance, both types occur one to several times per century per typical galaxy and both types seed the universe with the heavy elements essential to life. In spite of this, neither standard model provides a reasonably problem-free description of its target phenomenon. A major obstacle to providing a unified picture of supernovae would seem to be the fact that type …
Recent observations of a large fraction of Type II supernovae show traces of dense circumstellar medium (CSM) very close to the progenitor star. If this CSM is created by eruptive mass loss several months before core-collapse, the eruption itself may be visible as a precursor, helpful as an early warning of a near-future supernova. Using radiation hydrodynamical simulations based on the open-source code CHIPS, we theoretically model the emission from mass eruption of a red supergiant star. We find that for a modest mass eruption the luminosity is typically on the order of $10^{39}$ erg s$^{-1}…
Multi-dimensional fluid flow plays a paramount role in the explosions of massive stars as core-collapse supernovae. In recent years, three-dimensional (3D) simulations of these phenomena have matured significantly. Considerable progress has been made towards identifying the ingredients for shock revival by the neutrino-driven mechanism, and successful explosions have already been obtained in a number of self-consistent 3D models. These advances also bring new challenges, however. Prompted by a need for increased physical realism and meaningful model validation, supernova theory is now moving t…
An important result in core-collapse supernova (CCSN) theory is that spherically-symmetric, one-dimensional simulations routinely fail to explode, yet multi-dimensional simulations often explode. Numerical investigations suggest that turbulence eases the condition for explosion, but how is not fully understood. We develop a turbulence model for neutrino-driven convection, and show that this turbulence model reduces the condition for explosions by about 30%, in concordance with multi-dimensional simulations. In addition, we identify which turbulent terms enable explosions. Contrary to prior sug…
In a previously presented proof-of-principle study we established a parametrized spherically symmetric explosion method (PUSH) that can reproduce many features of core-collapse supernovae. The present paper goes beyond a specific application that is able to reproduce observational properties of SN1987A and performs a systematic study of the explosion properties for an extensive set of non-rotating, solar metallicity stellar progenitor models in the mass range from 10.8 to 120 M$_\odot$.This includes the transition from neutron stars to black holes as the final result of the collapse of massive…
Most massive stars experience binary interactions in their lifetimes that can alter both the surface and core structure of the stripped star with significant effects on their ultimate fate as core-collapse supernovae. However, core-collapse supernovae simulations to date have focused almost exclusively on the evolution of single stars. We present a systematic simulation study of single and binary-stripped stars with the same initial mass as candidates for core-collapse supernovae (11 - 21 M$_{\odot}$). Generally, we find that binary-stripped stars core tend to be less compact, with a more prom…
Charged current neutrino interactions in core-collapse supernovae in a virial expansion
核心坍缩超新星可能敏感地依赖于在温暖的低密度富中子物质中的带电中微子相互作用。在富中子物质中，质子比中子束缚得更紧。该能量移动ΔU增加了ν_e + n --> p + e中的电子能量，从而增加了可用的相空间和吸收截面。同样，ΔU降低了\bar v_e + p --> n + e^+中的正电子能量，从而减小了相空间和截面。我们用一个与模型无关的维里展开计算了ΔU，发现在低密度下，ΔU比许多平均场模型的预测大得多。因此，ΔU可能对超新星中的带电中微子相互作用有重大影响。对核心坍缩超新星吸积相的初步模拟发现，ΔU增加了\bar的ν e能量，降低了ν e光度。
In the current era of time-domain astronomy, it is increasingly important to have rigorous, data driven models for classifying transients, including supernovae. We present the first application of Principal Component Analysis to the spectra of stripped-envelope core-collapse supernovae. We use one of the largest compiled optical datasets of stripped-envelope supernovae, containing 160 SNe and 1551 spectra. We find that the first 5 principal components capture 79\% of the variance of our spectral sample, which contains the main families of stripped supernovae: Ib, IIb, Ic and broad-lined Ic. We…
