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Register a new userPre-collapse Properties of Superluminous Supernovae and Long Gamma-Ray Burst Progenitor Models
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Added by
David Aguilera-Dena
Publication date
2020
fields
Physics
and research's language is
English
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We analyze the properties of 42 rapidly rotating, low metallicity, quasi-chemically homogeneously evolving stellar models in the mass range between 4 and 45 $,mathrm{M}_odot$ at the time of core collapse. Such models were proposed as progenitors for both superluminous supernovae (SLSNe) and long duration gamma-ray bursts (lGRBs), and the Type Ic-BL supernovae (SNe) that are associated with them. Our findings suggest that whether these models produce a magnetar driven SLSN explosion or a near-critically rotating black hole (BH) is not a monotonic function of the initial mass. Rather, their explodability varies non-monotonically depending on the late core evolution, once chemical homogeneity is broken. Using different explodability criteria we find that our models have a clear preference to produce SLSNe at lower masses, and lGRBs at higher masses; but find several exceptions, expecting lGRBs to form from stars as low as 10 $,mathrm{M}_odot$, and SLSNe with progenitors as massive as 30 $,mathrm{M}_odot$. In general, our models reproduce the predicted angular momenta, ejecta masses and magnetic field strengths at core collapse inferred for SLSNe and lGRBs, and suggest significant interaction with their circumstellar medium, particularly for explosions with low ejecta mass.
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Multidimensional hydrodynamic simulations of shell convection in massive stars suggest the development of aspherical perturbations that may be amplified during iron core-collapse. These perturbations have a crucial and qualitative impact on the delayed neutrino-driven core-collapse supernova explosion mechanism by increasing the total stress behind the stalled shock. In this paper, we investigate the properties of a 15 msun model evolved in 1-,2-, and 3-dimensions (3D) for the final $sim$424 seconds before gravitational instability and iron core-collapse using MESA and the FLASH simulation framework. We find that just before collapse, our initially perturbed fully 3D model reaches angle-averaged convective velocity magnitudes of $approx$ 240-260 km s$^{-1}$ in the Si- and O-shell regions with a Mach number $approx$ 0.06. We find the bulk of the power in the O-shell resides at large scales, characterized by spherical harmonic orders ($ell$) of 2-4, while the Si-shell shows broad spectra on smaller scales of $ellapprox30-40$. Both convective regions show an increase in power at $ell=5$ near collapse. We show that the 1D texttt{MESA} model agrees with the convective velocity profile and speeds of the Si-shell when compared to our highest resolution 3D model. However, in the O-shell region, we find that texttt{MESA} predicts speeds approximately emph{four} times slower than all of our 3D models suggest. All eight of the multi-dimensional stellar models considered in this work are publicly available.
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