Axion resonances in binary pulsar systems

Abstract

We investigate the extent to which resonances between an oscillating background of ultra-light axion and a binary Keplerian system can affect the motion of the latter. These resonances lead to perturbations in the instantaneous time-of-arrivals, and to secular variations in the period of the binary. While the secular changes at exact resonance have recently been explored, the instantaneous effects have been overlooked. In this paper, we examine the latter using N-body simulations including the external oscillatory forcing induced by the axion background. While the secular effects are restricted to a narrow width near the resonance, the instantaneous changes, albeit strongest close to resonances, are apparent for wide range of configurations. We compute the signal-to-noise ratio (SNR) as a function of semi-major axis for a detection of axion oscillations through the RØmer delay. The latter can be extracted from the time-of-arrivals of binary pulsars. The SNR broadly increases with increasing binary eccentricity as expected from secular expectations. However, we find that it differs significantly from the scaling a5/2 around the lowest orders of resonance. Future observations could probe these effects away from resonances and, therefore, constrain a much broader range of axion masses provided that binary pulsar systems are found near the central region of our Galaxy, and that the time-or-arrival measurement accuracy reaches ≲ 10 ns.

Propagation of gravitational waves in Chern-Simons axion Einstein gravity

“…For these axions, there exists a primordial Uð1Þ symmetry which is unbroken quite earlier from the inflationary era, but it is broken during the inflationary era. The cosmological implications of the axions have quite appealing features and, in view of the growing research stream that is related with axion experiments and observations ( [12][13][14][15][16][17][18][19][20][21][22] see also [23]), axion physics has become quite timely. Actually, the axion may be one of the last realistic weakly interacting massive particles (WIMP) [24], since a longstanding number of experiments focusing on large WIMP masses ended up with no result.…”

Neutron Stars in f(R)-Gravity and Its Extension with a Scalar Axion Field

“…In particular, a realistic explanation is that dark matter consists of axions [34][35][36][37][38][39][40][41][42][43][44]. In contrast to failed experiments for WIMPs, there are some indications in favor of the existence of axions (see [45][46][47][48][49][50][51][52]). Axion emission can appears in the process of the cooling of neutron stars [53].…”

Passage of test particles through oscillating spherically-symmetric dark matter configurations

“…The gravitational field oscillations, produced by the oscillating DM, look like gravitational waves to an observer on Earth and would be detected in future laser interferometer experiments. An approach based on the observations of binary pulsars was discussed in [29,30] to probe of ultralight axion DM. It was shown that oscillations of DM resonantly perturb the orbits of the binary pulsars thus leading to secular variations in their orbital period.…”