Speaker
Description
Axionlike particles (ALPs) are predicted in many extensions of the Standard Model and are viable dark matter candidates. These particles could mix with photons in the presence of a magnetic field. Searching for the effects of ALP-photon mixing in gamma-ray observations of blazars has provided some of the strongest constraints on ALP parameter space so far. For the first time, we perform a combined analysis on Fermi Large Area Telescope data of three bright flaring flat-spectrum radio quasars, with the blazar jets themselves as the dominant mixing region. We include a full treatment of photon-photon dispersion within the jet and account for the uncertainty in our B-field model by leaving the field strength free in the fitting. Overall, we find no evidence for ALPs but are able to exclude the photon-ALP couplings > 5e-12 / GeV for ALP masses between 5 neV and 200 neV with 95% confidence. In this mass region, these are the strongest bounds on the photon-ALP coupling to date from gamma-ray observations.
| Collaboration / Activity | Fermi-LAT collaboration |
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