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Implications for particle dark matter if primordial black holes are detected with gravitational waves or radio observations


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Constraining weakly interacting massive particles with primordial black holes

DOI arXiv

Read the paper: arXiv:1905.01238.

Code authors: Adam Coogan, Daniele Gaggero and Bradley Kavanagh.

Reproducing results

The figures can be remade with the following commands:

  • Figure 1: python
  • Figure 2: python -plot_limits
  • Figure 3: python -plot_ps_diff

Computing the point-source limits requires making tables containing p_gamma, the probability that an individual PBH is detectable by Fermi-LAT. The tables used for the analysis in the paper are contained in the directory data/p_gammas/. These may take a few hours to recompute. They can be regenerated with python -test. With the -test flag, the p_gamma tables will be written to data/p_gammas/test/ instead of overwriting the precomputed tables. The script can also be used to generate p_gamma tables over different (m_dm, sv) grids.

All limit calculations require tabulated posteriors of f_pbh. These are provided in data/posteriors_f but they can be recomputed by running the script This script calls a number of scripts in src/ which calculate the posteriors from gravitational wave observations. Run python src/ -h and python src/ -h for more detailed usage of these scripts. Scripts for calculating posteriors from SKA will be added shortly.

bayesian branch

This branch contains code for performing a Bayesian analysis of the cross section limits.

  • The notebook plot_bayesian_limits.ipynb generates Bayesian versions of figures 2 and 3 assuming a uniform prior on the cross section.
  • generates tables of the posterior over a grid of (m_dm, sv) points for the diffuse analysis. The posterior is very simple: we marginalize over f, assume the background model for the EGB perfectly matches observations, and simply penalize the extragalactic flux from PBHs for exceeding zero using a Gaussian likelihood for each bin.
  • The analysis point-source analysis assumes that astrophysical sources can appear in the unassociated point source catalogue with an unknown rate, which we marginalize over assuming a Jeffreys prior. The script generates tables of p_gamma and the posterior over an (m_dm, sv) grid.


Implications for particle dark matter if primordial black holes are detected with gravitational waves or radio observations







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