  Significant research in compact stars is currently focused on two kinds of
enigmatic sources: anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters
(SGRs). Although AXPs and SGRs are popularly thought to be magnetars, other
models (e.g. the accretion model) to understand the observations can still not
be ruled out. It is worth noting that a non-detection in a Fermi/LAT
observation of AXP 4U 0142+61 has been reported recently by Sasmaz Mus & Gogus.
We propose here that Fermi/LAT observations may distinguish between the
magnetar model and the accretion model for AXPs and SGRs. We explain how this
null observation of AXP 4U 0142+61 favors the accretion model. Future Fermi/LAT
observations of AXP 1E 1547.0-5408 and AXP 1E 1048.1-5937 are highly
recommended.
