This is stellarcollapse.org, a website aimed at providing resources supporting research in stellar collapse, core-collapse supernovae, neutron stars, and gamma-ray bursts.

A large-scale dynamo and magnetoturbulence in rapidly rotating core-collapse supernovae, Nature Nov 30, 2015

We recently published our break-through study on magnetoturbulence in rapidly rotating stellar collapse online in Nature. We show that magnetohydrodynamic turbulence in the shear layer around a newly born proto-neutron star kicks off a highly efficient dynamo process that creates large-scale, ordered magnetar-strength (> 10^15 G) magnetic field. This field is strong enough to power hyperenergetic type Ic-bl explosions, a rare but extreme subclass of core-collapse supernovae, that are 10x more energetic than the average garden-variety supernovae and also make up all supernovae connected to long gamma-ray bursts. In addition, our simulations provide a first glimpse on a formation scenario for magnetars, very strongly magnetized neutron stars, that are left behind in these explosions.

The source code used to run the simulations and the initial data are available here. We have also created 3D visualizations of the magnetic field amplification in our simulations, embedded below.


Introducing SNEC: The SuperNova Explosion Code

Ever wanted to compute the light curve of a supernova explosion, but didn't have a code handy? Well, let us introduce SNEC, the SuperNova Explosion Code. SNEC is a new spherically-symmetric Lagrangian radiation-hydrodynamics code (in the flux-limited equilibrium diffusion approximation) that can explode stars and produce light curves (bolometric and various observational color bands). SNEC is open source and described in detail in Morozova et al. (2015), arXiv:1505.06746. All results shown in the Morozova et al. (2015) paper are fully reproducible.

Below plot shows light curves obtained from explosions of a 15-Msun star that has been systematically stripped (at a post-main-sequence stage) of hydrogen-rich envelope material in units of 1 Msun. See Morozova et al. (2015), arXiv:1505.06746 for further details.

You can download SNEC from stellarcollapse.org/SNEC and get simulation inputs and outputs from stellarcollapse.org/Morozova2015.

New: Observed BH Masses

We are pleased to announce a new section on stellarcollapse.org: Observed Black Hole Masses
Grzegorz Wiktorowicz and Chris Belcynski have been so kind to agree to collect this information and keep it up to date.

SNEC -- The SuperNova Explosion Code

Folks at Caltech have been working on a new open-source 1D Lagragian radiation-hydrodynamics for supernova explosions called SNEC -- The SuperNova Explosion Code. We are not quite ready to release the full code yet, but its hydro portion is already available on stellarcollapse.org: http://stellarcollapse.org/SNEC and has been used in Piro & Morozova, Transparent Helium in Stripped Envelope Supernovae, submitted to ApJL, arXiv:1407.5992.

What is the role of thermal pressure in hypermassive neutron star merger remants?

The merger of two neutron star creates a hypermassive, extremely rapidly and differentially spinning object (frequently called a hypermassive neutron star [HMNS]). While the premerger neutron stars can be treated as essentially being cold, the impact of the two NSs leads to very strong shocks that leave the HMNS with temperatures in the range of ~5-40 MeV (1 MeV corresponds to about 1.16 x 10^{10} K). For progenitor NSs in the typical NS mass range (1.3-1.4 solar masses), the HMNS will have more baryonic mass than can be supported by the nuclear equations of state and is believed to be supported by rapid differential rotation and, possibly, thermal pressure.

Kaplan et al. have investigated the role of thermal pressure support in HMNS and found something surprising and counter-intuitive: thermal pressure contributions do not appear to enhance the maximum HMNS mass; they do increase the baryonic mass supported by sub-critical configurations (i.e. not peak density, not critically rotating), but do not appear to give a significant boost to the overall maximum. Read more in Kaplan et al. 2013, which has been submitted to the Astrophysical Journal. It's available on arXiv! We provide some code and the employed equation of state tables here on stellarcollapse.org/Kaplanetal2013.

arXiv:1210.6674: Gravitational wave signals and source code available!

Ott et al. have submitted a new paper on 3D general-relativistic simulations of core-collapse supernovae. The gravitational-wave signals predicted from these simulations and the source code used for the leakage/heating scheme employed by the simulations are available for download at https://stellarcollapse.org/ottetal2012b.

Details in arXiv:1210.6674

New Neutron Star Mass Table

Jim Lattimer has been so kind to submit an updated version of his famous mass table. Take a look at it at stellarcollapse.org/nsmasses. This new version is based on Jim's Annual Review of Nuclear and Particle Physics article, which will appear in Volume 62.

New Microphysics

We have recently added several new microphysics tools and routines. The first is EOSmaker, this set of routines is what we use to construct our .h5 tables from the data tables provided from nuclear theorists. Along with this we have updated the H. Shen et al. table, which now uses the updated table from Shen, H. et al. (2011). The second tool is NuLib, a preliminary set of open-source neutrino interaction routines.

New Version of the H. Shen et al. EOS

Hong Shen of Nankai University and her collaborators K. Sumiyoshi (Numazu College of Technology, Japan) and H. Toki (RIKEN, Osaka, Japan) have updated their relativistic-mean field EOS tables (Shen et al. 1998a, 1998b) and are providing new tables in ASCII format that are equally spaced, have a greater range and a finer temperature mesh. The tables can be obtained from their Shen et al. EOS web page. We are in the process of incorporating these new tables into our full collapse EOS tables provided on the microphysics/EOS page.

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