stellarcollapse.org - Community Resources for the Stellar Collapse and Compact Object Community

Welcome!

cott — Sun, 15 Mar 2009 23:45:03 +0000

Welcome! cott Mon, 03/16/2009 - 00:45

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

Gravitational Waves from Binary Black Hole Mergers Inside of Stars

cott — Wed, 26 Apr 2017 05:28:32 +0000

Gravitational Waves from Binary Black Hole Mergers Inside of Stars cott Wed, 04/26/2017 - 07:28

New paper out by Fedrow et al., arXiv:1704.07383

Abstract

We present results from a controlled numerical experiment investigating the effect of stellar density gas on the coalescence of binary black holes (BBHs) and the resulting gravitational waves (GWs). This investigation is motivated by the proposed stellar core fragmentation scenario for BBH formation and the associated possibility of an electromagnetic counterpart to a BBH GW event. We employ full numerical relativity coupled with general-relativistic hydrodynamics and set up a $30 + 30 M_\odot$ BBH (motivated by GW150914) inside gas with realistic stellar densities. Our results show that at densities $\rho \gtrsim 10^6 - 10^7 \, \mathrm{g \, cm}^{-3}$ dynamical friction between the BHs and gas changes the coalescence dynamics and the GW signal in an unmistakable way. We show that for GW150914, LIGO observations conclusively rule out BBH coalescence inside stellar gas of $\rho \gtrsim 10^7 \, \mathrm{g\,cm}^{-3}$. Typical densities in the collapsing cores of massive stars are in excess of this density. This excludes the fragmentation scenario for the formation of GW150914.

Richers et al. 2017: Equation of State Effects on Gravitational Waves from Rotating Core Collapse

cott — Sun, 22 Jan 2017 17:35:23 +0000

Richers et al. 2017: Equation of State Effects on Gravitational Waves from Rotating Core Collapse cott Sun, 01/22/2017 - 18:35

Richers et al., arXiv:1701.02752 carried out more than 1800 axisymmetric general-relativistic simulations of rotating core collapse, using 18 different nuclear equations of state. The gravitational waveforms are available here on stellarcollapse.org!

New version of SNEC -- The SuperNova Explosion Code available!

cott — Wed, 12 Oct 2016 22:02:23 +0000

New version of SNEC -- The SuperNova Explosion Code available! cott Thu, 10/13/2016 - 00:02

We have released version 1.01 of SNEC -- it's available for download from stellarcollapse.org/SNEC. SNEC 1.01 implements the same physics as SNEC 1.00, but is about a factor of two faster thanks to various optimizations.

How loud are Neutron Star Mergers?

cott — Fri, 05 Aug 2016 23:18:39 +0000

How loud are Neutron Star Mergers? cott Sat, 08/06/2016 - 01:18

Our new paper led by Sebastiano Bernuzzi is out in Physical Review D! The paper is about a large set of neutron star merger simulations, using three different finite-temperature nuclear equation of state and binary parameters motivated by the galactic double neutron star population. Our focus was on how "loud" these mergers are in gravitational waves and what phase of their evolution is the "loudest".

Also exciting: We are providing open access to the gravitational waveforms extracted from our merger simulations. For details, see: https://stellarcollapse.org/Bernuzzi2016. Here is the money plot from the paper:

This figure shows that most of the gravitational wave energy in the entire history of a coalescing neutron star binary is actually emitted in the first ~10 ms after merger

Updated Neutron Star Mass Table!

cott — Thu, 26 May 2016 19:36:17 +0000

Updated Neutron Star Mass Table! cott Thu, 05/26/2016 - 21:36

Jim Lattimer has been so kind to provide us with an updated version of his observed neutron star masses table. See here: https://stellarcollapse.org/nsmasses

Red Supergiant Radii and the Rise Times of SN IIP Light Curves

cott — Wed, 30 Mar 2016 03:10:11 +0000

Red Supergiant Radii and the Rise Times of SN IIP Light Curves cott Wed, 03/30/2016 - 05:10

New paper by Viktoriya Morozova, Tony Piro, Mathieu Renzo, Christian Ott:

"Numerical Modeling of the Early Light Curves of Type IIP Supernovae", submitted to ApJ, arXiv:1603.08530.

We show, using SNEC, that there is a tight correlation between Type IIP (plateau) core-collapse supernova rise times (in g-band) and the radii of their progenitor red supergiant stars. See below figure! SNEC and all inputs to our models are available as part of our open-science initiative here on stellarcollapse.org: https://stellarcollapse.org/Morozova2016

Morozova et al. 2016, arXiv:1603.08530

We don't just do core collapse: New Neutron Star Merger results in!

cott — Mon, 21 Mar 2016 08:51:40 +0000

We don't just do core collapse: New Neutron Star Merger results in! cott Mon, 03/21/2016 - 09:51

The One-Armed Spiral Instability in Neutron Star Mergers and its Detectability in Gravitational Waves

Radice, Bernuzzi, & Ott, arXiv:1603.05726, read more here: https://stellarcollapse.org/BNSm1

stellarcollapse.org moved to new server

cott — Thu, 03 Mar 2016 13:58:17 +0000

stellarcollapse.org moved to new server cott Thu, 03/03/2016 - 14:58

Welcome to the new stellarcollapse.org! We just completed the move to a new server with faster CPUs and more disk space. We have upgraded the content management system from Drupal 6 to Drupal 8. Stay tuned for more simulation results that will appear soon on stellarcollapse.org!

Please contact Christian Ott at cott #at# tapir.caltech.edu if you notice any problems with the site.

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

pmoesta — Thu, 03 Dec 2015 22:10:02 +0000

A large-scale dynamo and magnetoturbulence in rapidly rotating core-collapse supernovae, Nature Nov 30, 2015 pmoesta Thu, 12/03/2015 - 23:10

Mösta et al. recently published a break-through study on magnetoturbulence in rapidly rotating stellar collapse in Nature. They 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, their 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. They have also created 3D visualizations of the magnetic field amplification in their simulations, embedded below.