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Constructs neutron star models in the context of regularized 4D Einstein-Gauss-Bonnet gravity, using the KEH/CST numerical scheme.

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cppEGB

Description

Code for obtaining static neutron star solutions in regularized 4D Einstein-Gauss-Bonnet gravity1, for tabulated EoS2, using the KEH/CST numerical scheme3. A C++ version of the Savitzky-Golay filter4 is used, along with some modules from the BOOST C++ library5. In addition the C++ code is wrapped using SWIG6, into a python library which can be imported and used in any way, as shown in swig/test.py.

Usage

Compile, using the provided makefile.

EGB.exe takes 7 inputs in total. The parameters are specified using the following flags:

  1. -f eos_name (The EoS file name).
  2. -c coupling (The EGB coupling constant in km^2).
  3. -e central_pressure (The central pressure in dyn/cm^2/10^35).
  4. -t relative_error (The relative error for the iteration scheme).
  5. -m maximum_iterations (The maximum number of iterations).
  6. -l relaxation_factor
  7. -p print_option:
    • 0: Prints gravitational mass M and radius R.
    • 1: Prints (0) along with the distance, metric, scalar, energy density and pressure profiles.

For example,

./EGB -f ppsly4.cold.rns1.1.txt -c 20.0 -e 10.0 -t 1e-05 -m 100 -l 0.2 -p 0

typical input parameter space:

  • central pressure ~ 0.1-30.0 (10^35 dyn/cm^2)
  • coupling ~ 0-70 (km^2)

Footnotes

  1. https://iopscience.iop.org/article/10.1088/1475-7516/2022/02/033

  2. https://ui.adsabs.harvard.edu/abs/2021PhRvD.103l3004B/abstract (table IX)

  3. https://academic.oup.com/mnras/article/237/2/355/976460, https://ui.adsabs.harvard.edu/abs/1992ApJ...398..203C/abstract, https://gitlab.com/niksterg/rns1-1/

  4. https://github.com/arntanguy/sgsmooth

  5. https://github.com/boostorg/boost

  6. https://github.com/swig/swig

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Constructs neutron star models in the context of regularized 4D Einstein-Gauss-Bonnet gravity, using the KEH/CST numerical scheme.

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