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 part of the Cluster of Excellence “Quantum Universe” which includes leading scientists from mathematics, particle physics, astrophysics, and cosmology at Hamburg University and DESY.

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 the potential of cryogenic detectors for the future International Axion Observatory (IAXO). 

News

before july 2022

Previous news

Previous news can be found in our archive.

4 july 2022

Contributions to Gamma Symposium

Our group presented results on the magnetic field modeling for ALP searches in M87 as well as new constraints on the intergalactic magnetic field (IGMF) at the 7th Heidelberg International Symposium on High-Energy Gamma-Ray Astronomy in Barcelona. The new IGMF constraints are featured in this press release and we are preparing scientific publications on the presented topics - stay tuned!

15 july 2022

Three bachelor students work with us over the summer 

We are very delighted to have three undergrad students with us over the summer who will work on their final bachelors thesis. The thesis topics include the application of machine learning algorithms to ALPS II data, lab work in connection with the ALPS II transition edge sensor, as well as the characterization of the gamma-ray emission of particular blazar.  

1 august 2022

New postdoc joins our team 

The University of Mainz hosted two special events on "wavy dark matter" this summer: a summer school in Bad Honnef as well as the Patras workshop in Mainz. Joule and Manuel gave lectures at the summer school and also presented research results at the Patras workshop. 

1 october 2022

Sara Porras Bedmar, our new PhD student, has arrived

We are very happy that Sara Porras Bedmar is joining our team. Sara got her masters degree in astrophysics and cosmology from the Universidad Autónoma de Madrid (working in the DAMASCO group). Sara will work on the contribution of axion/ALP decays to diffuse photons fields. Welcome!

august 2022

Our contributions to the wavy dark matter summer

Together with Jonathan Biteau from the Université Paris-Sud, we wrote a review article on propagation of gamma rays over cosmological distances. We hope to give a broad overview and make it easier for new students to enter this exciting field of research. It's open access and available here.

8 november 2022

New constraints on photon-axion mixing from Fermi observations

In this work led by Jamie Davies we derive new constraints on photon-axion mixing in magnetic fields of bright flat spectrum radio quasars using Fermi-LAT observations. For the first time, our gamma-ray constraints probe a new region of the axion parameter space up to axion masses of 200 neV. The paper is submitted to PRD and available on arxiv (see also our research result section).

The Team

Our research team with current, past, and associated members

Group leader
University of Hamburg
Personal homepage

PostDoc
University of Hamburg
(working on ALPS)

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

PhD Student
Oxford University
(working on Fermi-LAT )

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

Research results

A list with our latest results and publications

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. Such observations offer large statistics to search for wiggles in energy spectra that could be produced when photons convert into ALPs in the magnetic fields of FSRQ jets. 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 submitted to PRD and available as a preprint 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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