Active Galactic Nuclei Shed Light on Axionlike Particles

We demonstrate that the scatter in the luminosity relations of astrophysical objects can be used to search for axionlike particles. This analysis is applied to observations of active galactic nuclei, where we find evidence highly suggestive of the existence of a very light axionlike particle.

Figure 1

Histograms of second ($k_2$) and third ($k_3$) moments [see Eq. (8)] for ${10}^5$ resamplings of 77 data points (a) simulated with the best-fit Gaussian scatter ($\sigma =0.34$), (b) simulated with the best-fit ALP mixing model ($\sigma =0.23$), and (c) from the observed scatter in the AGN $L_X-L_o$ relation. Darker regions indicate higher density. See text for discussion.