Jul 3 – 8, 2016
The University of Melbourne
Australia/Melbourne timezone

Searches for Axion-Like Particles with NGC1275: Observation of Spectral Modulations

Jul 7, 2016, 5:30 PM
Carillo Gantner Theatre

Carillo Gantner Theatre

Carrillo Gantner Theatre, Sidney Myer Asia Centre The University of Melbourne VIC 3010 Australia
Talk Dark Matter and Particle Astrophysics Dark Matter and Particle Astrophysics


Nicholas Jennings (University of Oxford)


Axion-like particles (ALPs) can induce localised O(10%) oscillatory modulations in the spectra of photon sources passing through astrophysical magnetic fields. Ultra-deep Chandra observations of the Perseus cluster contain over 5×10^5 counts from the central NGC1275 AGN and represent a dataset of extraordinary quality for ALP searches. We use these to search for X-ray spectral irregularities from the AGN. The absence of irregularities at the O(30%) level allows us to place leading constraints on the ALP-photon mixing parameter g_aγγ≲1.5−5.4×10^{−12}GeV^{−1} for axion mass m_a≲10^{−12}eV, depending on assumptions on the magnetic field realisation along the line of sight. At O(10%) level two modulations are present at high statistical significance, an excess in the 2-2.2 keV region and a deficit at 3.4-3.5 keV. We are unable to account for these through conventional instrumental or astrophysical processes and, interpreted as a signal, they would correspond to an ALP-photon coupling in the range g_aγγ∼1−5×10^{−12}GeV^{−1}. This talk is based on 1605.01043.

Primary authors

Andrew J Powell (University of Oxford) Francesca Day (University of Oxford) Joseph Conlon (Oxford University) Marcus Berg (Karlstad University) Markus Rummel Nicholas Jennings (University of Oxford) Sven Krippendorf (University of Oxford)

Presentation materials