New limits on the photon mass with radio pulsars in the Magellanic clouds

Abstract

A conservative constraint on the rest mass of the photon can be estimated under the assumption that the frequency dependence of dispersion from astronomical sources is mainly contributed by the nonzero photon mass effect. Photon mass limits have been earlier set through the optical emissions of the Crab Nebula pulsar, but we prove that these limits can be significantly improved with the dispersion measure (DM) measurements of radio pulsars in the Large and Small Magellanic Clouds. The combination of DM measurements of pulsars and distances of the Magellanic Clouds provide a strict upper limit on the photon mass as low as m γ ≤ 2.0 × 10 −45 g, which is at least four orders of magnitude smaller than the constraint from the Crab Nebula pulsar. Although our limit is not as tight as the current best result (∼ 10 −47 g) from a fast radio burst (FRB 150418) at a cosmological distance, the cosmological origin of FRB 150418 remains under debate; and our limit can reach the same high precision of FRB 150418 when it has an extragalactic origin (∼ 10 −45 g).

Robust limits on photon mass from statistical samples of extragalactic radio pulsars

“…One can see from this plot that at the respectively. These 68% and 95% confidence-level limits are comparable with that obtained by a single LMC pulsar [14].…”

“…Using the observed dispersion measures from two samples of extragalactic pulsars, we place robust limits on the photon mass at the 68% (95%) confidence level, i.e., m γ ≤ 1.51 × 10 −48 kg (m γ ≤ 2.42 × 10 −48 kg) for the sample of 22 radio pulsars in the LMC and m γ ≤ 1.58 × 10 −48 kg (m γ ≤ 2.43 × 10 −48 kg) for the other sample of 5 radio pulsars in the SMC. Compared with previous limits from a single pulsar in each of the LMC and SMC [14], our 95% confidence-level constraints from statistical samples are equally good. Although our limits on the photon mass are two orders of magnitude worse than the current best limit from a single FRB [10][11][12], there is merit to the results.…”

Symmetron scalar fields: Modified gravity, dark matter, or both?

“…Constraints on the photon mass also arise from cosmological observations of gamma ray bursts [87], extra-galactic pulsars [88,89] and fast radio bursts [90][91][92], which give the tightest constraint m γ 10 −14 eV. These constraints are significantly weaker than those obtained from cosmological measurements.…”

FRB 121102 casts new light on the photon mass

“…For pioneering studies using astrophysical sources, see [15] (flare stars) and [16] (Crab nebula), and for an analogous subsequent study with greater sensitivity to the photon mass, see [17] (GRB 980703, m γ < 4.2×10 −47 kg). The most recent such studies are those in [18] (GRB 050416A, m γ < 1.1 × 10 −47 kg) and [19] (radio pulsars in the Magellanic clouds, m γ < 2 × 10 −48 kg). Our limit on m γ is significantly stronger.…”