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dc.contributor.authorDay, Francescaen
dc.contributor.authorMcDonald, Jamie Ien
dc.date.accessioned2019-11-23T00:30:53Z
dc.date.available2019-11-23T00:30:53Z
dc.date.issued2019-10en
dc.identifier.issn1475-7516
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/299166
dc.description.abstractIt is a well-known fact that compact gravitating objects admit bound state configurations for massive bosonic fields. In this work we describe a new class of superradiant instabilities of axion bound states in neutron star magnetospheres. The instability arises from the mixing of axion and photon modes in the magnetic field of the neutron star which extract energy from the rotating magnetosphere. Unlike for black holes, where the dissipation required for superradiance is provided by an absorbative horizon, the non-hermitian dynamics in this paper come from the resistivity in the stellar magnetosphere arising from a finite bulk conductivity. The axion field mixes with photon modes which superradiantly scatter off the magnetosphere, extracting rotational energy which is then deposited back into the axion sector leading to an instability. We derive the superradiant eigenfrequencies for the axion-photon system using quantum mechanical perturbation theory on the axion boundstate, drawing an analogy with atomic selection rules. We then compare the characteristic time scale of the instability to the spin-down measurements of pulsars which limit the allowed rate of angular momentum extraction from neutron stars.
dc.rightsAll rights reserved
dc.rights.uri
dc.subjectaxionsen
dc.subjectdark matter theoryen
dc.subjectpulsar magnetosphereen
dc.titleAxion superradiance in rotating neutron starsen
dc.typeArticle
prism.issueIdentifier10en
prism.numberARTN 051en
prism.publicationDate2019en
prism.publicationNameJOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICSen
dc.identifier.doi10.17863/CAM.46231
dcterms.dateAccepted2019-10-13en
rioxxterms.versionofrecord10.1088/1475-7516/2019/10/051en
rioxxterms.versionAM
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserveden
rioxxterms.licenseref.startdate2019-10en
dc.contributor.orcidDay, Francesca [0000-0001-9475-8856]
dc.identifier.eissn1475-7516
rioxxterms.typeJournal Article/Reviewen
cam.orpheus.successThu Jan 30 10:35:28 GMT 2020 - Embargo updated*
rioxxterms.freetoread.startdate2020-10-23


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