Detecting axionlike dark matter with linearly polarized pulsar light

Abstract

Non-relativistic QCD axions or axion-like particles are among the most popular candidates for cold Dark Matter (DM) in the universe. We proposed to detect axion-like DM, using linearly polarized pulsar light as a probe. Because of birefringence effect potentially caused by an oscillating galactic axion DM background, when pulsar light travels across the galaxy, its linear polarization angle may vary with time. With a soliton+NFW galactic DM density profile, we show that this strategy can potentially probe an axion-photon coupling as small as ∼ 10 −13 GeV −1 for axion mass ma ∼ 10 −22 − 10 −20 eV, given the current measurement accuracy. An exclusion limit stronger than CAST (∼ 10 −10 GeV −1 ) and SN1987A (∼ 10 −11 GeV −1 ) could be extended up to ma ∼ 10 −18 eV and ∼ 10 −19 eV, respectively.

Probing the angle of birefringence due to long range axion hair from pulsars

“…When the electromagnetic radiation passes through this long range axion hair, it rotates the polarization of electromagnetic radiation and produces birefringence. The obtained birefringent angle due to axion photon interaction is within the accuracy of measuring the linear polarization angle of pulsar light which is ≤1.0° [43,48,51]. The obtained birefringent angle strictly continues to hold for axions with inverse mass greater than the radius of pulsar (10 km) which gives m a < 10 −11 eV.…”

“…Any systematic deviation (≤1.0° [43,48,51]) in the linear polarization angle can be due to the long range axion hair. External magnetic field can also give rise such type of rotation of the polarization vector which is called the Faraday effect.…”

“…Strong dipolar magnetic field induces E:B density outside the pulsar which can also be a source of pseudoscalar axion and can rotate the polarization vector of the electromagnetic radiation [42]. There can also be galactic axion dark matter background which can rotate the polarization of the pulsar light [43]. The ALP dark matter background also rotates the cosmic microwave background modes which constrain the mass of the axion and axion photon coupling constant [44].…”

Constraints on axions from cosmic distance measurements

“…A better understanding of the magnetic field in ICM could help reduce the uncertainties associated with its modeling. In addition, positive detection of axion-photon coupling from future experiments probing axion-photon coupling in this mass range [83][84][85][86] could help fix these bounds. Lastly, with future improvements in the precision of cosmic distance measurements, a better determination of late-time Hubble diagram H(z) is expected, which could further improve the sensitivity to possible departures from the ΛCDM prediction due to photon-axion conversion.…”

Gravitational Waves and Possible Fast Radio Bursts from Axion Clumps

“…The result is an explosion of the photon number in the resonance frequency k * = m a /2, as in the mechanism a → γγ described in the introduction. This effect has been amazingly linked to the observed multiple FRBs in the galaxy, in both the axion dense object case [11][12][13][14][15] and black hole superradiance [19,[23][24][25][26]. Especially it is for the peak frequency,…”