Rejuvenated accretors have less bound envelopes

Impact of Roche lobe overflow on subsequent common envelope events

Most isolated binary evolution scenarios for gravitational-wave sources rely on a common envelope (CE) to reduce the separation (exceptions are chemically homogeneous evolution and stable mass transfer channels). The CE is often initiated by a star that has previously accreted mass during a stable Roche lobe overflow (RLOF) phase.

We study how the previous accretion through RLOF influences the radial evolution and the binding energy profile of the accretor star. This is different than profiles of genuinely single stars, because accretion of matter from a companion leads to increase of the convective core mass, rejuvenation, and changes in the density, temperature, entropy, and composition of the star and ultimately its binding energy profile.

Our result broadly indicate that having accreted mass during the main sequence leads to evolved stars with overall less bound envelopes that might be easier to eject in a CE, suggesting a higher CE survival rate and wider post-CE orbital sepatations.

For more info, see the article (accepted by ApJL, arXiv:2206.15338). Our MESA simulations input and output are publicly available on zenodo, and processed data produced by the scripts are also publicly available as a showyourwork-managed cache also on zenodo.

How to build the article locally

(See also the showyourwork documentation)

Assuming you have a working installation of conda, you can install showyourwork, clone this repository, and just run showyourwork and it should work:

pip install -U showyourwork
git clone git@github.com:mathren/CE_accretors.git
cd CE_accretors
showyourwork

The first time this will download the data (1.7 Gb) and process them – unpacking up to 8.3 Gb of MESA output. Downloading, unpacking the data, and pre-processing them may take long (~30min on my workstation including the time to download the data):

time showyourwork
[...]
showyourwork 1081s
user         27m9.104s
sys          0m59.076s

After the data exist cached on your machine, this will be much faster (how much depends on what has changed in the repo that needs to be redone).

You can also edit and should be able to compile locally the tex file (see below). If you have never ran showyourwork locally, then the figures will be missing on your machine (but you can still compile using the draft option). If you have ever ran showyourwork you will have a (possibly outdated) version of the figures locally, and you can compile the tex as you would usually.

Structure of the repository

This follows the structure prescribed by showyourwork.

src/tex LaTeX files for the paper

The figures pdf are not saved in the git repo, instead they are generated by showyourwork.

src/scripts python scripts for the paper

Contains the scripts and libraries used for the analysis and to make the figures in the paper

src/data/

When running showyourwork locally, the data will be downloaded from zenodo and saved in a subfolder MESA_output, which the python scripts expect to exist before they can run.

src/data/MESA_input

The subfolders here contain template MESA work directory used to run our models. Tarball containing the exact template used for the models in the paper are also uploaded on zenodo – the template here may evolve in the future.

This project uses MESA version 15140, MESA SDK x86_64-linux-20.12.1 (also logged in the *.data files), which includes the compiler:

gfortran --version
GNU Fortran (GCC) 10.2.0

Please refer to the MESA documentation and mailing list for support.