First lower limits on the photon-axion-like particle coupling from very high energy gamma-ray observations

By M. Meyer, D. Horns, Martina Raue. 2013

173 citations recorded by the source corpus.

The intrinsic flux of very high energy (VHE, Energy > 100 GeV) gamma-rays from extragalactic sources is attenuated due to pair production in the interaction with photons of the extragalactic background light (EBL). Depending on the distance of the source, the Universe should be opaque to VHE photons above a certain energy. However, indications exist that the Universe is more transparent than previously thought. A recent statistical analysis of a large sample of VHE spectra shows that the correction for absorption with current EBL models is too strong for the data points with the highest attenuation. An explanation might be the oscillation of VHE photons into hypothetical axion-like particles (ALPs) in ambient magnetic fields. This mechanism would decrease the opacity as ALPs propagate unimpeded over cosmological distances. Here, a large sample of VHE gamma-ray spectra obtained with imaging air Cherenkov telescopes is used to set, for the first time, lower limits on the photon-ALP coupling constant over a large range of ALP masses. The conversion in different magnetic field configurations, including intra-cluster and intergalactic magnetic fields together with the magnetic field of the Milky Way, is investigated taking into account the energy dependence of the oscillations. For optimistic scenarios of the intervening magnetic fields, a lower limit on the photon-ALP coupling of the order of $10^{-12}\mathrm{GeV}^{-1}$ is obtained whereas more conservative model assumptions result in $2\times10^{-11}\mathrm{GeV}^{-1}$. The latter value is within reach of future dedicated ALP searches.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/ecba7a6118a97ac17490451ad711f1f3616470fa

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Citations in the corpus

Revised constraints and Belle II sensitivity for visible and invisible axion-like particles (2017, background): “ALPs can constitute cold dark matter (DM) [12] and have also been considered as possible explanations for a range of astrophysical anomalies, such as the over-efficient cooling of certain classes of stars [13], the surprising transparency of the Universe to very high-energy γ-rays [14] or the hints ”
Sensitivity projections for dark matter searches with the Fermi large area telescope (2016, background): “Future LAT observations of distant AGNs could also provide an additional step forward to testing ALPs as a possible solution to the suggested reduced opacity of the Universe to γ rays [262, 266, 279, 280].”
New experimental approaches in the search for axion-like particles (2018, methodology): “A better defined region in the (gaγ,ma) plane is obtained in [360] from the analysis of a large sample of VHE gamma-ray spectra.”
THE EXTRAGALACTIC BACKGROUND LIGHT, THE HUBBLE CONSTANT, AND ANOMALIES: CONCLUSIONS FROM 20 YEARS OF TeV GAMMA-RAY OBSERVATIONS (2015, methodology): “…based on the largest gamma-ray sample studied so far, that current VHE gamma-ray observations do not show a detectable flux enhancement at large optical depths and find little motivation for a lower limit on the coupling of axion-like particles with photons as reported in Meyer et al. (2013).”
Recent Progress in the Physics of Axions and Axion-Like Particles (2020, background): “Although not convincing enough, there are few astrophysical anomalies that might be explained by axions with certain specific mass and coupling [15–17].”
Revisiting the SN1987A gamma-ray limit on ultralight axion-like particles (2014, background): “on in the last few years. Indeed, the astrophysical hints from TeV photons require ALPs with ma .10−7 eV and gaγ &10−12–10−11 GeV−1 depending on the assumptions for the cosmological magnetic ﬁeld [45]. Moreover, this range is within the reach of the planned upgrade of the photon-regeneration exp”
Any Light Particle Search II -- Technical Design Report (2013, background): “s questions (cold Dark Matter candidates, in gray, and predictions from string theory around g ag ˘10 12 GeV 1, not colored) as well as astrophysical hints: TeV transparency (red, ﬁducial region, cf. [25]) and WD cooling (light red band)). In addition the parameter region excluded from the 1987a sup”
New axion and hidden photon constraints from a solar data global fit (2015, background): “ALPs can be behind some very interesting hints recently pointed out in astrophysics like the transparency of the universe to gamma-rays [46], the 3.”