nubhlight is a code for simulating disks of materials around black holes formed after the in-spiral and merger of two-black holes. It is based on the open-source code bhlight. nubhlight models all relevant physics required to solve the post-merger disk problem. This includes: general relativity in a static spacetime, neutrino and weak physics, relativistic magnetohydrodynamics, and the ability to use open-sourced tabulated equations of state provided by stellarcollapse.org.
nubhlight is based on the open-source code bhlight. (bhlight is available here: https://github.com/AFD-Illinois/ebhlight) bhlight has the following capabilities and methods:
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Finite volumes are used to model general relativistic magnetohydrodynamics as described in Gammie, McKinney, and Toth, 2006 (see: https://doi.org/10.1086/374594).
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A Monte Carlo method to model radiation, as described in Dolence et al., 2009 (see: https://doi.org/10.1088/0067-0049/184/2/387).
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The radiation and fluid sectors are are coupled together via operator splitting as described in Ryan, Dolence, and Gammie, 2015 (see: https://doi.org/10.1088/0004-637X/807/1/31).
The following changes were made at LANL to turn bhlight into nubhlight:
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The equation of state for the relativistic magnetohydrodynamics was extended to conserve electron number and to include open-source tabulated data provided by stellarcollapse.org
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Radiation packets were changed to model neutrinos of three flavors: electron neutrino, electron antineutrino, all other flavors grouped together as "heavy" neutrinos.
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Tracer particles were added
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All details of required changes can be found in Miller, Ryan, and Dolence, 2019 (see: https://doi.org/10.3847/1538-4365/ab09fc).
nubhlight is useful for astrophysics research on black hole accretion. It is a research code and has no other uses and has no commercial applications.
nubhlight was developed by author Jonah Miller during his postdoc at LANL. Development work began in February 2018 and finished in March, 2019.
The software additions needed (to create the nubhlight product from the existing bhlight product) were created at LANL.
Software additions needed to create nubhlight from bhlight were undertaken to support fundamental research (as defined in NSDD-189) for modelling disks of material formed around black holes after neutron star mergers. The nubhlight code aids in open astrophysics work performed by the code author. This work supports an LDRD grant on this fundamental research topic, as well as research for an Office of Science SciDAC grant. The original SciDAC program plan can be found here: https://www.scidac.gov/documents/SciDAC.pdf.
nubhlight was created from the open source software project bhlight by extending it in several ways that were called out above in the code details section. The link for bhlight is also listed above and details of its licensing can be found there.
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DOE office of science SciDAC project
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LDRD through the Center for Nonlinear Studies
Linux only. Tested on Debian 4.0 and above.
GNU compiler only.
nubhlight is written in C99 and Fortran90. However, the build system and data analysis utilities uses python 3.
nubhlight has the following software dependencies, which it links against. (Source code for dependencies not included. Dependencies must be pre-installed on target machine.)
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GNU scientific library (https://www.gnu.org/software/gsl/)
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Any implementation of the MPI protocol, such as OpenMPI (https://www.open-mpi.org/)
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The hierarchical data format, HDF5 (https://www.hdfgroup.org/downloads/hdf5/)
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python 3 (https://www.python.org/)
Additionally, data analysis tools provided along with nubhlight use the scientific python software stack and rely on the following libraries:
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h5py (https://www.h5py.org/)
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numpy (https://numpy.org/)
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scipy (https://www.scipy.org/)
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matplotlib (https://matplotlib.org/)