About us

The Axion Dark Matter research group focuses on searches for dark matter in the form of axions and axion-like particles (ALPs) both in astrophysical observations and dedicated laboratory experiments. It is supported by a Starting Grant from the European Research Council. The group is hosted at the Center for Cosmology and Particle Physics Phenomenology (CP3 Origins) University of Southern Denmark (SDU) in Odense and at the Institute for Experimental Physics at Hamburg University.  

The nature of dark matter, which makes up more than 80% of the total matter in the Universe, is one of the most pressing questions in fundamental particle physics, astrophysics, and cosmology. Axions and ALPs are promising dark matter candidates which could produce specific observational signatures in astrophysical observations and in laboratory searches.

Please feel free to contact us for potential thesis projects!

  1. Astrophysical searches - We use astrophysical observations with the H.E.S.S. telescopes, the Large Area Telescope (LAT) on board the Fermi satellite, and the Cherenkov Telescope Array (CTA) to search for signatures of the conversion of axions and ALPs into high energy gamma rays. 
  2. Laboratory searches - We contribute to the next generation of laboratory experiments dedicated to the search for axions and ALPs. In particular, we help in the commissioning of the transition edge sensor detector for the ALPS II experiment and develop analysis tools based on machine learning. We also investigate novel experimental ideas.


before May 2023

Previous news

Previous news can be found in our archive.

June 2023

Start of ALPS II

On May 23, ALPS II started it's initial science run - we are very excited to begin the hunt for axions. Read press releases here and here.

June 2023

Two new papers out

We’re happy to share that two more works of our groups are accepted for publication. On one machine-learning applications to our TES data, the other one on constraints on the intergalactic magnetic field.

July 2023

Joule receives PIER seed funding

Our post doc Joule receives seed funding from PIER to investigate our photon-number-resolving capabilities of our transition edge sensor for characterizing so-called squeezed light states. Congratulations Joule!

August 2023

Contributions to the EPS HEP Meeting

The biggest European meeting on high energy physics took place in Hamburg this summer. Our group was well represented with 3 posters and one talk!

September 2023

Atreya joins our team!

Our new post doc, Atreya has arrived. Atreya did his PhD in Durham and after that went to Huntsville, Alabama, to work on VERITAS and CTA. We’re extremely happy to have him back in Europe, welcome!

The Team

Our research team with current associated members. Past members can be found here
A list of theses published from our group is available here.
Please get in touch for potential bachelor or master projects!

Group leader
Personal homepage

University of Hamburg
(working on ALPS)

(working on H.E.S.S. and Fermi-LAT )

PhD student
University of Hamburg
(working on H.E.S.S.)

PhD student
University of Hamburg
(working on astrophysical axion/ALP searches)

Masters student
University of Hamburg
(working on Fermi LAT)

Research results

A list with our latest results and publications. You can also find our papers on NASA ADS, inspire HEP, and Scopus

New constraints on the strength of the intergalactic magnetic field using H.E.S.S. and Fermi-LAT observations

We re-analyzed gamma-ray data from certain distant galaxies taken with the H.E.S.S. and Fermi telescopes to search for extended gamma-ray emission around these sources. Usually, we believe that these sources could be pointlike, but gamma-ray induced particle cascades could lead to a halo around them. The size of the halo depends on the strength of intergalactic magnetic fields. We didn't see any sign of extended emission, which leads to new strong constraints on the magnetic field strength. Our findings our published in the Astrophysical Journal Letters and also available here

A first application of Machine learning for signal and background discrimination of the ALPS II TES

For the first time, we have applied machine learning to data of our transition edge sensor in order to improve the rejection of unwanted background counts. As it turns out, approaches using neural networks outperform our previous analysis methods and suggest that we can efficiently suppress our dark current levels. Check out the full paper published in Annals of Physics or on the arXiv

New constraints on photon-axion-like-particle mixing in magnetic fields of jets of flat spectrum radio quasars

We used Fermi-LAT observations of bright gamma-ray outbursts of flat spectrum radio quasars (FSRQs) to search for oscillations between photons and axion-like particles. For the first time, we self-consistently include photon-photon dispersion off the radiation fields in these environments and let the magnetic field free to vary in our fitting. For the first time we are able to constrain the ALP photon coupling for ALP masses up to 200 neV with gamma-ray observations. The paper is published in PRD and available here.

The effect of photon-photon dispersion on photon-axion-like-particle oscillations in blazars 

In the presence of dense photon fields in the vicinity of gamma-ray production sites in the jets of active galactic nuclei, the conversion of photons into axion-like particles competes with photon-photon interactions such as dispersion and photon absorption. In our recent study, which is accepted in PRD (and available on the arxiv) we show that both effects are important to include when searching for ALP signatures in the spectra of these sources.

Searching for Axion-Like Particles from Core-Collapse Supernovae with Fermi LAT's Low Energy Technique

We estimate the sensitivity of the low energy technique of the LAT to detect a gamma-ray burst caused by the conversion of axion-like particles produced in extragalactic core collapse supernovae. We find that we could detect such a burst from supernovae in galaxies up to 10 Mpc (~30 million light years) away. The study is accepted for publication in PRD and available as a preprint on arxiv

Enlarging the sample of extragalactic supernovae to search for an axion-like-particle-induced gamma-ray burst 

We have identified 15 core collapse supernovae observed with the Zwicky Transient facility (ZTF) that are potentially well suited to search for a gamma-ray burst signal produced from axion-like particles. With the continued operation of ZTF and the upcoming Rubin Observatory, this sample will grow significantly in the near future. Check out the proceedings article for the ICRC2021 on arxiv and our original study published in 2020 in PRL.

gammaALPs code

An open-source python package that calculates the conversion probability between gamma rays and axions/ALPs in various astrophysical magnetic-field environments. Check out the documentation here and the proceedings article for the ICRC 2021.

CTA Sensitivity study for gamma-ray cosmology and fundamental physics

Using realistic simulations of future observations with CTA of active galactic nuclei, we present the sensitivity of CTA to detect signatures of axions and ALPs, to constrain the extragalactic background light, detect intergalactic magnetic fields, and search for Lorentz Invariance Violation. The paper is accepted in JCAP and you can find the preprint here

Photon-ALP oscillations in more realistic jet models

Together with Jamie Davies from Oxford, we have put out a paper about the oscillations of photons into axion-like particles in the magnetic fields of jets of active galaxies. It turns out that the exact morphology of the magnetic field in the jet can be quite important - we need multiwavelength data to constrain it. Check out the paper published in PRD here

The Axion - ALP - DM research group is funded by an ERC starting grant and hosted by the University of Hamburg.

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