Particle Astrophysics & Dark Matter


Selected Publications

An anomalous emission component at energies of a few gigaelectronvolts and located towards the inner Galaxy is present in the Fermi-LAT data. At present, the two most promising explanations are the annihilation of dark matter particles or the presence of a large population of unresolved point sources, most probably millisecond pulsars, at the Galactic Centre. Here, we report an analysis of the excess characteristics using almost eight years of Pass 8 ULTRACLEAN Fermi-LAT data with SkyFACT—a tool that combines image reconstruction with template-fitting techniques. We find that an emission profile that traces stellar mass in the boxy and nuclear bulge is preferred over conventional dark matter profiles. A model including the bulge is favoured over a model with dark matter at 16σ.

Using gamma-ray data from the Fermi Large Area Telescope, we confirm previous claims of a hardning of the cosmic ray spectrum, extend these results to more than 100 GeV, and argue that the observations cannot be caused by unresolved sources in the sub-TeV energy range. We discuss implications for cosmic ray propagation in the Galaxy.


Master students, PhD students & postdocs


  • Marco Chianese (2018 - …)
  • Bradley Kavanagh (2017 - …)
  • Antonella Garzilli (2016 - 2017)
  • Emma Storm (2015 - …)
  • Francesca Calore (2014 - 2015)

PhD students

  • Thomas Edwards (2015 - …)
  • Suraj Krishnamurthy (2014 - …)
  • Richard Bartels (2014 - …)
  • Roberta Diamanti (2013 - 2017, co-supervision with Shin’ichiro Ando)
  • Hamish Silverwood (2012 - 2016, co-supervision with Gianfranco Bertone)


  • Mikael Leroy (Oct 2018 - Jun 2019)

Master students

  • Paul Hofma (Sep 2018 - …)
  • Aliki Litsa (Sep 2018 - …)
  • Mart Pothast (2017 - 2018)
  • Kathleen Short (2016 - 2017)
  • Maikel Doornhein (2016 - May 2018)

For information about possible Bachelor and Master projects in my group checkout out the GRAPPA website.


Collaborations & Public Codes

Dark Machines

Dark Machines is a research collective of physicists and data scientists. We are curious about the universe and want to answer cutting edge questions about Dark Matter with the most advanced techniques that data science provides us with.


Global and Modular BSM Inference Tool


Utilising the power of MeerKAT, TRAPUM will discover numerous new pulsars and transient events in order to expand our knowledge of the populations of sources which emit at radio wavelengths on timescales ranging from microseconds to seconds.


Likelihoods for indirect dark matter searches with gamma rays


A Python tool to study the information yield of counting experiments.


At the University of Amsterdam, I teach the following courses.

Bachelor Physics and Astronomy:

Master Physics and Astronomy:


Recent and upcoming

Dark Matter Searches with Gamma Rays
Apr 25, 2018
Disentangling the gamma-ray emission from the Galactic bulge
Apr 19, 2018
Can we trust an excess in indirect DM searches?
Apr 11, 2018
Indirect dark matter searches with charged cosmic rays and sub-GeV photons
Feb 21, 2018
Fast model discrimination with Euclideanized signals
Jan 15, 2018

Recent Publications

A full list of publications can be found on

Galactic Binaries Can Explain the Fermi Galactic Center Excess and 511 keV Emission


On the progressive hardening of the cosmic-ray proton spectrum in the inner Galaxy