Physics Letters B 757 (2016) 548–552
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Physics Letters B
www.elsevier.com/locate/physletb
Photon mass limits from fast radio bursts
Luca Bonetti
a,b
, John Ellis
c,d
, Nikolaos E. Mavromatos
c,d
, Alexander S. Sakharov
e,f,g,∗
,
Edward K. Sarkisyan-Grinbaum
g,h
, Alessandro D.A.M. Spallicci
a,b
a
Observatoire des Sciences de l’Univers en région Centre, UMS 3116, Université d’Orléans, 1A rue de la Férollerie, 45071 Orléans, France
b
Laboratoire de Physique et Chimie de l’Environnement et de l’Espace, UMR 7328, Centre Nationale de la Recherche Scientifique, LPC2E, Campus CNRS, 3A Avenue
de la Recherche Scientifique, 45071 Orléans, France
c
Theoretical Particle Physics and Cosmology Group, Physics Department, King’s College London, Strand, London WC2R 2LS, United Kingdom
d
Theoretical Physics Department, CERN, CH-1211 Genève 23, Switzerland
e
Department of Physics, New York University, 4 Washington Place, New York, NY 10003, United States
f
Physics Department, Manhattan College, 4513 Manhattan College Parkway, Riverdale, NY 10471, United States
g
Experimental Physics Department, CERN, CH-1211 Genève 23, Switzerland
h
Department of Physics, The University of Texas at Arlington, 502 Yates Street, Box 19059, Arlington, TX 76019, United States
a r t i c l e i n f o a b s t r a c t
Article history:
Received
5 March 2016
Received
in revised form 30 March 2016
Accepted
17 April 2016
Available
online 20 April 2016
Editor:
G.F. Giudice
We
dedicate this paper to the memory of
Lev Okun, an expert on photon mass
The frequency-dependent time delays in fast radio bursts (FRBs) can be used to constrain the photon
mass, if the FRB redshifts are known, but the similarity between the frequency dependences of dispersion
due to plasma effects and a photon mass complicates the derivation of a limit on m
γ
. The dispersion
measure (DM) of FRB 150418 is known to ∼ 0.1%, and there is a claim to have measured its redshift
with an accuracy of ∼ 2%, but the strength of the constraint on m
γ
is limited by uncertainties in the
modelling of the host galaxy and the Milky Way, as well as possible inhomogeneities in the intergalactic
medium (IGM). Allowing for these uncertainties, the recent data on FRB 150418 indicate that m
γ
1.8 × 10
−14
eV c
−2
(3.2 × 10
−50
kg), if FRB 150418 indeed has a redshift z = 0.492 as initially reported.
In the future, the different redshift dependences of the plasma and photon mass contributions to DM
can be used to improve the sensitivity to m
γ
if more FRB redshifts are measured. For a fixed fractional
uncertainty in the extra-galactic contribution to the DM of an FRB, one with a lower redshift would
provide greater sensitivity to m
γ
.
Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP
3
.
When setting an upper limit on the photon mass, the Parti-
cle
Data Group (PDG) [1] cites the outcome of modelling the so-
lar
system magnetic field: first at 1 AU, m
γ
< 5.6 × 10
−17
eV c
−2
(= 10
−52
kg) [2,3], and later at 40 AU, m
γ
< 8.4 × 10
−19
eV c
−2
(= 1.5 ×10
−54
kg) [2]. However, the laboratory upper limit is four
orders of magnitude larger [4]; for reviews see [5,6]. In [6], the
authors state the concern that “Quoted photon-mass limits have at
times been overly optimistic in the strengths of their characterizations.
This is perhaps due to the temptation to assert too strongly something
one ‘knows’ to be true”. This concern was mainly addressed to the
galactic magnetic field model limits [7], but it should be borne in
mind also when assessing the solar system limits.
Indeed,
the estimates on the deviations from Ampère’s law in
the solar wind [2,3] are not based simply on in situ measurements.
For example: (i) the magnetic field is assumed to be exactly, al-
*
Corresponding author.
E-mail
address: Alexandre.Sakharov@cern.ch (A.S. Sakharov).
ways and everywhere a Parker spiral; (ii) the accuracy of particle
data measurements from, e.g., Pioneer or Voyager, has not been
discussed; (iii) there is no error analysis, nor data presentation,
instead; (iv) there is extensive use of a reductio ad absurdum ap-
proach
based on earlier results of other authors, which are often
devoted to other issues than establishing a basis for an extremely
difficult measurement of a mass that is many orders of magnitude
lower than that of an electron or a neutrino.
In
order to check these estimates of the solar wind at 1 AU,
a more experimental approach has been pursued via a thorough
analysis of Cluster data [8], leading to a mass upper limit lying
between 1.4 × 10
−49
and 3.4 × 10
−51
kg, according to the esti-
mated
potential. The difference between the results of this con-
servative
approach and previous estimates, as well as the need for
astrophysical modelling, motivates the development of additional
methods for constraining the photon mass.
The
time structures of electromagnetic emissions from astro-
physical
sources at cosmological distances have been used to con-
strain
other aspects of photon/electromagnetic wave propagation,
http://dx.doi.org/10.1016/j.physletb.2016.04.035
0370-2693/Published
by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP
3
.