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

July 2021

Contributions to ICRC

Our work was featured with multiple contributions at the ICRC 2021 which was held online this time, see our research results section!

1 august 2021

New PhD student arrived

Our first PhD student, Rahul Cecil, is joining our team. Rahul got his masters degree in astroparticle phyiscs from the University of Tübingen and will focus on ALP searches with the H.E.S.S. telescopes and the Fermi LAT.

16 september 2021

New paper on the LAT sensitivity for axion induced gamma-ray bursts accepted!

The study, led by Milena Crnogorčević from the University of Maryland, explores the sensitivity of the LAT low energy technique to detect gamma-ray bursts from core collapse supernovae caused by axions converting to gamma rays in the magnetic field of the Milky Way. Check out more details in the research results

1 november 2021

New postdoc joins our team 

Gulden (Joule) Othman joins our team after having successfully defended her PhD thesis at the University of North Carolina at Chapel Hill. Joule will help us to set up the TES detector for the ALPS II experiment. Welcome Joule!

15 december 2021

New paper on photon-photon dispersion in active galaxies accepted in PRD

During his research stay in Hamburg, our affiliated member Jamie managed to finish his paper on the effect of photon-photon dispersion on photon-ALP oscillations in active galaxies. Congratulations Jamie! Check out more details in the research results.

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 )

Research results

A list with our latest results and publications

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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