Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userImportance of $^{56}$Ni production on diagnosing explosion mechanism of core-collapse supernova
61
0
0.0
(
0
)
Authors
Yudai Suwa
Ask ChatGPT about the research
No Arabic abstract
$^{56}$Ni is an important indicator of the supernova explosions, which characterizes light curves. Nevertheless, rather than $^{56}$Ni, the explosion energy has often been paid attention from the explosion mechanism community, since it is easier to estimate from numerical data than the amount of $^{56}$Ni. The final explosion energy, however, is difficult to estimate by detailed numerical simulations because current simulations cannot reach typical timescale of saturation of explosion energy. Instead, the amount of $^{56}$Ni converges within a short timescale so that it would be a better probe of the explosion mechanism. We investigated the amount of $^{56}$Ni synthesized by explosive nucleosynthesis in supernova ejecta by means of numerical simulations and an analytic model. For numerical simulations, we employ Lagrangian hydrodynamics code in which neutrino heating and cooling terms are taken into account by light-bulb approximation. Initial conditions are taken from Woosley & Hegel (2007), which have 12, 15, 20, and 25 $M_odot$ in zero age main sequence. We additionally develop an analytic model, which gives a reasonable estimate of the amount of $^{56}$Ni. We found that, in order to produce enough amount of $^{56}$Ni, $mathcal{O}(1)$ Bethe s$^{-1}$ of growth rate of the explosion energy is needed, which is much larger than that found in recent exploding simulations, typically $mathcal{O}(0.1)$ Bethe s$^{-1}$.
rate research
Read More
An attempt is made to assess the significance of rotation in the core-collapse supernova phenomenon, from both observational and theoretical point of view. The data on supernovae particularly indicative of the role of rotation in the collapse-triggered explosion is emphasized. The problem of including the rotation of presupernova core into the supernova theory is considered. A two-dimensional classification scheme of core-collapse supernovae is proposed which unifies classical supernovae of type Ib/c and type II, hypernovae and some GRB events.
We have been working within the fundamental paradigm that core collapse supernovae (CCSNe) may be neutrino driven, since the first suggestion of this by Colgate and White nearly five decades ago. Computational models have become increasingly sophisticated, first in one spatial dimension assuming spherical symmetry, then in two spatial dimensions assuming axisymmetry, and now in three spatial dimensions with no imposed symmetries. The increase in the number of spatial dimensions has been accompanied by an increase in the physics included in the models, and an increase in the sophistication with which this physics has been modeled. Computation has played an essential role in the development of CCSN theory, not simply for the obvious reason that such multidimensional, multi-physics, nonlinear events cannot possibly be fully captured analytically, but for its role in discovery. In particular, the discovery of the standing accretion shock instability (SASI) through computation about a decade ago has impacted all simulations performed since then. Today, we appear to be at a threshold, where neutrinos, neutrino-driven convection, and the SASI, working together over time scales significantly longer than had been anticipated in the past, are able to generate explosions, and in some cases, robust explosions, in a number of axisymmetric models. But how will this play out in three dimensions? Early results from the first three-dimensional (3D), multi-physics simulation of the Oak Ridge group are promising. I will discuss the essential components of todays models and the requirements of realistic CCSN modeling, present results from our one-, two-, and three-dimensional models, place our models in context with respect to other efforts around the world, and discuss short- and long-term next steps.
Most supernova explosions accompany the death of a massive star. These explosions give birth to neutron stars and black holes and eject solar masses of heavy elements. However, determining the mechanism of explosion has been a half-century journey of great complexity. In this paper, we present our perspective of the status of this theoretical quest and the physics and astrophysics upon which its resolution seems to depend. The delayed neutrino-heating mechanism is emerging as a robust solution, but there remain many issues to address, not the least of which involves the chaos of the dynamics, before victory can unambiguously be declared. It is impossible to review in detail all aspects of this multi-faceted, more-than-half-century-long theoretical quest. Rather, we here map out the major ingredients of explosion and the emerging systematics of the observables with progenitor mass, as we currently see them. Our discussion will of necessity be speculative in parts, and many of the ideas may not survive future scrutiny. Some statements may be viewed as informed predictions concerning the numerous observables that rightly exercise astronomers witnessing and diagnosing the supernova Universe. Importantly, the same explosion in the inside, by the same mechanism, can look very different in photons, depending upon the mass and radius of the star upon explosion. A 10$^{51}$-erg (one Bethe) explosion of a red supergiant with a massive hydrogen-rich envelope, a diminished hydrogen envelope, no hydrogen envelope, and, perhaps, no hydrogen envelope or helium shell all look very different, yet might have the same core and explosion evolution.
The mass of synthesised radioactive material is an important power source for all supernova (SN) types. Anderson 2019 recently compiled literature values and obtained $^{56}$Ni distributions for different core-collapse supernovae (CC-SNe), showing that the $^{56}$Ni distribution of stripped envelope CC-SNe (SE-SNe: types IIb, Ib, and Ic) is highly incompatible with that of hydrogen rich type II SNe (SNe-II). This motivates questions on differences in progenitors, explosion mechanisms, and $^{56}$Ni estimation methods. Here, we re-estimate the nucleosynthetic yields of $^{56}$Ni for a well-observed and well-defined sample of SE-SNe in a uniform manner. This allows us to investigate whether the observed SN-II--SE-SN $^{56}$Ni separation is due to real differences between these SN types, or because of systematic errors in the estimation methods. We compiled a sample of well observed SE-SNe and measured $^{56}$Ni masses through three different methods proposed in the literature. Arnetts rule -as previously shown - gives $^{56}$Ni masses for SE-SNe that are considerably higher than SNe-II. While for the distributions calculated using both the Khatami&Kasen prescription and Tail $^{56}$Ni masses are offset to lower values than `Arnett values, their $^{56}$Ni distributions are still statistically higher than that of SNe II. Our results are strongly driven by a lack of SE-SN with low $^{56}$Ni masses (that are in addition strictly lower limits). The lowest SE-SN $^{56}$Ni mass in our sample is of 0.015M$_odot$, below which are more than 25$%$ of SNe II. We conclude that there exists real, intrinsic differences in the mass of synthesised radioactive material between SNe II and SE-SNe . Any proposed current or future CCSN progenitor scenario and explosion mechanism must be able to explain why and how such differences arise, or outline a yet to be fully explored bias in current SN samples.
In this work we report briefly on the gravitational wave (GW) signal computed in the context of a self-consistent, 3D simulation of a core-collapse supernova (CCSN) explosion of a 15M$_odot$ progenitor star. We present a short overview of the GW signal, including signal amplitude, frequency distribution, and the energy emitted in the form of GWs for each phase of explosion, along with neutrino luminosities, and discuss correlations between them.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
