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DOI arXiv License: MIT

A collection of bounds on primordial black holes (PBHs) and code for plotting them.

Messy summary of all PBH bounds


The list of available, tabulated bounds is in the bounds/ folder (see the readme there). The fact that I've included or omitted a particular bound shouldn't be taken as an endorsement or otherwise. I'll leave the user to exercise their own judgement when choosing which bounds are relevant. Note also that some of the bounds plotted above as dashed lines are projections.


If you'd like to add a bound to the repo, there are a few options:

  1. Make the changes yourself:
    • Add the new bound as a .txt file in the bounds/ folder. Each file should have two columns, corresponding to the PBH mass in Solar mass, and the constraint on the PBH fraction. Also include a comment at the top of the file giving a link to the source of the bound.
    • Update the bounds/ file with information about the new bound.
    • Submit a pull request
  2. Create an issue here on the github repo, pointing to the paper/bound which is missing.
  3. Contact me directly at and let me know which bound you think should be added.


Some example plots summarising the bounds are in the plots/ folder.

You can produce a plot with

python -listfile LIST_FILE -outfile OUT_FILE

where LIST_FILE is a text file containing a list of bounds to be plotted (see listfiles/list_all.txt for an example) and OUT_FILE is the full filename of the image to be output (e.g. plots/PBHbounds.pdf). You can use the short flags -lf and -of for specifying the list file and output file.

A dark theme (with black background and white text) can be set using the flag --dark.

The plot style and some of the bounds are inspired by arXiv:1801.00808.

Constraints on the primordial power spectrum can be plotted with


which is roughly inspired by plots from arXiv:1811.11158, arXiv:1812.00674 and arXiv:1909.01593.



  • 22/03/2022: Added new bounds from microlensing of quasars (arXiv:2203.04777)
  • 07/03/2022: Added long duration microlensing constraints from arXiv:2202.13819
  • 22/02/2022: Added new EDGES 21cm constraints from Mittal et al. (2021), presented in arXiv:2107.02190
  • 04/05/2021: Added some projected constraints in the asteroid-mass region, as well as a new flag for dark themes.
  • 24/03/2021: Added Lyman alpha forest constraint and SKA forecast, shown in arXiv:2103.12087.
  • 13/01/2021: Added code for plotting Power Spectrum constraints (Fig. 1 of PBH review).
  • 20/07/2020: Substantial updates, to coincide with PBH review article (more details to follow).
  • 07/01/2020: added bounds on PBH evaporation from 511 keV gamma ray line

Version 1.0 (12/11/2019): Release version. Created for the first GW4FP workshop (Amsterdam 2019).


Feel free to use the bounds and code for anything you like, but please link to the repo if you do and cite the DOI: 10.5281/zenodo.3538999.

Papers using PBHbounds

An incomplete list of papers which make use of PBHbounds. Please get in touch if you've used the code or digitised bounds, so I can keep track!

  • Can breakdown of perturbation in the α-attractor inflation lead to PBH formation?, Sarkar et al., arXiv:2112.05408


Code for plotting bounds on the abundance of primordial black holes (PBHs)







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