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Register a new userThe Radio Luminosity-Risetime Function of Core-Collapse Supernovae
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Michael F. Bietenholz
Publication date
2020
fields
Physics
and research's language is
English
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We assemble a large set of 2-10 GHz radio flux density measurements and upper limits of 294 different supernovae (SNe), from the literature and our own and archival data. Only 31% of the SNe were detected. We characterize the SN lightcurves near the peak using a two-parameter model, with $t_{rm pk}$ being the time to rise to a peak and $L_{rm pk}$ the spectral luminosity at that peak. Over all SNe in our sample at $D<100$ Mpc, we find that $t_{rm pk} = 10^{1.7pm0.9}$ d, and that $L_{rm pk} = 10^{25.5pm1.6}$ erg s$^{-1}$ Hz$^{-1}$, and therefore that generally, 50% of SNe will have $L_{rm pk} < 10^{25.5}$ erg s$^{-1}$ Hz$^{-1}$. These $L_{rm pk}$ values are ~30 times lower than those for only detected SNe. Types I b/c and II (excluding IIns) have similar mean values of $L_{rm pk}$ but the former have a wider range, whereas Type IIn SNe have ~10 times higher values with $L_{rm pk} = 10^{26.5pm1.1}$ erg s$^{-1}$ Hz$^{-1}$. As for $t_{rm pk}$, Type I b/c have $t_{rm pk}$ of only $10^{1.1pm0.5}$ d while Type II have $t_{rm pk} = 10^{1.6pm1.0}$ and Type IIn the longest timescales with $t_{rm pk} = 10^{3.1pm0.7}$ d. We also estimate the distribution of progenitor mass-loss rates, $dot M$, and find the mean and standard deviation of log$_{10}(dot M/$Msol) yr$^{-1}$ are $-5.4pm1.2$ (assuming $v_{rm wind}=1000$ km s$^{-1}$) for Type I~b/c SNe, and $-6.9pm1.4$ (assuming $v_{rm wind} = 10$ km s$^{-1}$ for Type II SNe excluding Type IIn.
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Hydrogen-rich core collapse supernovae, known as Type II supernovae, are the most common type of stellar explosion realized in nature. They are defined by the presence of prominent hydrogen lines in their spectra. Type II supernovae are observed only in star-forming galaxies, and several events have been directly linked to massive star progenitors. Five main subclasses are identified: Type IIP (displaying a plateau in their light curve), Type IIL (displaying a light curve decline), Type IIn (displaying narrow emission lines), Type IIb (displaying increasingly strong He features with time) and 87A-likes (displaying long-rising light curves similar to that of SN 1987A). Type IIP supernovae have been robustly established as the explosions of red supergiants, while the progenitors of Type IILs remain elusive. Type IIns are likely linked to luminous blue variables, Type IIb progenitors may be interacting binary systems and the prototype of the 87A-like class was observed to be the explosion of a blue supergiant. The diversity in progenitor mass, metallicity, binarity and rotation is likely responsible for the diversity in observed explosion types, but the connection between progenitor parameters and supernova properties is not yet entirely understood theoretically nor fully mapped observationally. New observational methods for constraining this connection are currently being implemented, including the analyses of large samples of events, making use of very early data (obtained hours to days from explosion) and statistical studies of host-galaxy properties.
We investigate correlated gravitational wave and neutrino signals from rotating core-collapse supernovae with simulations. Using an improved mode identification procedure based on mode function matching, we show that a linear quadrupolar mode of the core produces a dual imprint on gravitational waves and neutrinos in the early post-bounce phase of the supernova. The angular harmonics of the neutrino emission are consistent with the mode energy around the neutrinospheres, which points to a mechanism for the imprint on neutrinos. Thus, neutrinos carry information about the mode amplitude in the outer region of the core, whereas gravitational waves probe deeper in. We also find that the best-fit mode function has a frequency bounded above by $sim 420$ Hz, and yet the modes frequency in our simulations is $sim 15%$ higher, due to the use of Newtonian hydrodynamics and a widely used pseudo-Newtonian gravity approximation. This overestimation is particularly important for the analysis of gravitational wave detectability and asteroseismology, pointing to limitations of pseudo-Newtonian approaches for these purposes, possibly even resulting in excitation of incorrect modes. In addition, mode frequency matching (as opposed to mode function matching) could be resulting in mode misidentification in recent work. Lastly, we evaluate the prospects of a multimessenger detection of the mode using current technology. The detection of the imprint on neutrinos is most challenging, with a maximum detection distance of $sim!1$ kpc using the IceCube Neutrino Observatory. The maximum distance for detecting the complementary gravitational wave imprint is $sim!5$ kpc using Advanced LIGO at design sensitivity.
Core-collapse supernovae are among Natures most energetic events. They mark the end of massive star evolution and pollute the interstellar medium with the life-enabling ashes of thermonuclear burning. Despite their importance for the evolution of galaxies and life in the universe, the details of the core-collapse supernova explosion mechanism remain in the dark and pose a daunting computational challenge. We outline the multi-dimensional, multi-scale, and multi-physics nature of the core-collapse supernova problem and discuss computational strategies and requirements for its solution. Specifically, we highlight the axisymmetric (2D) radiation-MHD code VULCAN/2D and present results obtained from the first full-2D angle-dependent neutrino radiation-hydrodynamics simulations of the post-core-bounce supernova evolution. We then go on to discuss the new code Zelmani which is based on the open-source HPC Cactus framework and provides a scalable AMR approach for 3D fully general-relativistic modeling of stellar collapse, core-collapse supernovae and black hole formation on current and future massively-parallel HPC systems. We show Zelmanis scaling properties to more than 16,000 compute cores and discuss first 3D general-relativistic core-collapse results.
Core-collapse supernovae, the culmination of massive stellar evolution, are spectacular astronomical events and the principle actors in the story of our elemental origins. Our understanding of these events, while still incomplete, centers around a neutrino-driven central engine that is highly hydrodynamically unstable. Increasingly sophisticated simulations reveal a shock that stalls for hundreds of milliseconds before reviving. Though brought back to life by neutrino heating, the development of the supernova explosion is inextricably linked to multi-dimensional fluid flows. In this paper, the outcomes of three-dimensional simulations that include sophisticated nuclear physics and spectral neutrino transport are juxtaposed to learn about the nature of the three dimensional fluid flow that shapes the explosion. Comparison is also made between the results of simulations in spherical symmetry from several groups, to give ourselves confidence in the understanding derived from this juxtaposition.
We investigate the post-explosion phase in core-collapse supernovae with 2D hydrodynamical simulations and a simple neutrino treatment. The latter allows us to perform 46 simulations and follow the evolution of the 32 successful explosions during several seconds. We present a broad study based on three progenitors (11.2 $M_odot$, 15 $M_odot$, and 27 $M_odot$), different neutrino-heating efficiencies, and various rotation rates. We show that the first seconds after shock revival determine the final explosion energy, remnant mass, and properties of ejected matter. Our results suggest that a continued mass accretion increases the explosion energy even at late times. We link the late-time mass accretion to initial conditions such as rotation strength and shock deformation at explosion time. Only some of our simulations develop a neutrino-driven wind that survives for several seconds. This indicates that neutrino-driven winds are not a standard feature expected after every successful explosion. Even if our neutrino treatment is simple, we estimate the nucleosynthesis of the exploding models for the 15 $M_odot$ progenitor after correcting the neutrino energies and luminosities to get a more realistic electron fraction.
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