Searching for Axion-Like Particles with X-ray Polarimeters

Day, Francesca; Krippendorf, Sven

doi:10.3390/galaxies6020045

Cited by 30 publications

(15 citation statements)

References 45 publications

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“…Since there are a large number of different coherence volumes for the magnetic field, this leads a random modulation of the quasar spectrum caused by conversion and reconversion. Such modulations are not observed, and consequently exclude values of g aγ 6 − 8 × 10 −13 GeV −1 [122,123] excluding f K 4 × 10 9 GeV. This bound also increases like N 1/4 .…”

Section: Outlook: Axion Couplings To the Visible Sector At Large H 11mentioning

confidence: 84%

Superradiance in String Theory

Mehta,

Demirtas,

Long

et al. 2021

Preprint

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We perform an extensive analysis of the statistics of axion masses and interactions in compactifications of type IIB string theory, and we show that black hole superradiance excludes some regions of Calabi-Yau moduli space. Regardless of the cosmological model, a theory with an axion whose mass falls in a superradiant band can be probed by the measured properties of astrophysical black holes, unless the axion selfinteraction is large enough to disrupt formation of a condensate. We study a large ensemble of compactifications on Calabi-Yau hypersurfaces, with 1 ≤ h 1,1 ≤ 491 closed string axions, and determine whether the superradiance conditions on the masses and self-interactions are fulfilled. The axion mass spectrum is largely determined by the Kähler parameters, for mild assumptions about the contributing instantons, and takes a nearly-universal form when h 1,11. When the Kähler moduli are taken at the tip of the stretched Kähler cone, the fraction of geometries excluded initially grows with h 1,1 , to a maximum of ≈ 0.5 at h 1,1 ≈ 160, and then falls for larger h 1,1 . Further inside the Kähler cone, the superradiance constraints are far weaker, but for h 1,1 100 the decay constants are so small that these geometries may be in tension with astrophysical bounds, depending on the realization of the Standard Model.

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Section: Outlook: Axion Couplings To the Visible Sector At Large H 11mentioning

confidence: 84%

Superradiance in String Theory

Mehta,

Demirtas,

Long

et al. 2021

Preprint

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“…The modulation can be modelled statistically with a stochastic model for cluster magnetic fields. The strongest bound arises from the observation of a single source, NGC1275, by the Chandra satellite, which observed no modulations and sets the 3𝜎 limit [162,163] 𝑔 𝑎𝛾𝛾 < 6-8 × 10 −13 GeV −1 (for 𝑚 𝑎 10 −12 eV) .…”

Section: Axion-photon Conversionmentioning

confidence: 99%

Astrophysical Searches and Constraints on Ultralight Bosonic Dark Matter

Marsh¹,

Hoof²

2021

Preprint

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Starting from the evidence that dark matter (DM) indeed exists and permeates the entire cosmos, various bounds on its properties can be estimated. Beginning with the cosmic microwave background and large scale structure, we summarize bounds on the ultralight bosonic dark matter (UBDM) mass and cosmic density. These bounds are extended to larger masses by considering galaxy formation and evolution, and the phenomenon of black hole superradiance. We then discuss the formation of different classes of UBDM compact objects including solitons/axion stars and miniclusters. Next, we consider astrophysical constraints on the couplings of UBDM to Standard Model particles, from stellar cooling (production of UBDM) and indirect searches (decays or conversion of UBDM). Throughout, there are short discussions of "hints and opportunities" in searching for UBDM in each area. Astrophysical search channelsAstrophysics and cosmology, as outlined in Chapter 1, give convincing evidence that dark matter (DM) exists in the form of new particles beyond the Standard Model of particle physics. The space of possible theories in Chapter 2, even for the subclass of ultralight bosonic DM (UBDM) models considered in this book, is vast. Beyond the basic fact of the existence of DM, astrophysics can be used to reign in this vast theoretical parameter space, with a view to direct detection and measurement of model parameters.The most basic astrophysical route to constrain UBDM is via the relic density. There are three channels for UBDM production:1. Coherent field oscillations. a. Vacuum realigment. b. Topological defect decay.2. Thermal production. 3. Non-thermal production by direct decay.

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“…Consequences of photon-ALP interaction on the polarization of photons produced by gamma-ray bursts have been analyzed in [38], and photon-ALP conversion effects on the polarization of photons originated from other astrophysical sources have been studied e.g. in [39][40][41][42][43][44]. In addition, new attention on this topics has been recently paid because of some existing or proposed experiments that measure the polarization of cosmic photons in the X-ray band like IXPE [45] and Polstar [46] and in the high-energy (HE) band such as COSI [47], e-ASTROGAM [48,49] and AMEGO [50].…”

Section: Introductionmentioning

confidence: 99%

Photon-ALP oscillations inducing modifications to photon polarization

Galanti¹

2022

Preprint

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Axion-like particles (ALPs) are very light, neutral, spin zero bosons predicted by many theories which try to extend and complete the standard model of elementary particles. ALPs interact primarily with two photons and can generate photon-ALP oscillations in the presence of an external magnetic field. They are attracting increasing interest since photon-ALP oscillations produce deep consequences in astrophysics particularly in the very-high-energy (VHE) band, where they increase the transparency of the Universe to VHE photons by partially preventing absorption caused by the extragalactic background light. Furthermore, ALPs explain why photons coming from flat spectrum radio quasars (a particular class of active galactic nuclei, AGN) have been observed for energies above 20 GeV -which represents a first hint for the existence of an ALP. In addition, ALPs solve an anomalous redshift dependence of blazar (an AGN class) spectra -which represents a second hint for the existence of an ALP. In this paper, we study another effect of the photon-ALP interaction: the change of the polarization state of photons. In particular, we study the propagation of the photon-ALP beam starting where photons are produced -we consider photons generated in a galaxy cluster or in the jet of a blazar -crossing several magnetized media (blazar jet, host galaxy, galaxy cluster, extragalactic space, Milky Way) up to their arrival at the Earth, where photons can be detected. In the presence of photon-ALP interaction, we analyze the photon survival probability Pγ→γ and the corresponding photon degree of linear polarization ΠL for observed energies in the range (1 − 10 15 ) eV dividing it into three energy bands: (i) X-ray band (10 −3 keV − 10 2 keV), (ii) high-energy (HE) band (10 −1 MeV − 10 4 MeV), (iii) VHE band (10 −2 TeV − 10 3 TeV). We observe that photons, which are expected as unpolarized in the absence of ALPs, are made partially polarized by photon-ALP interaction, which generally modifies the initial photon degree of linear polarization ΠL,0 in a sizable and measurable way. Our findings about the X-ray and HE bands can be tested by current and planned observatories like IXPE, Polstar, COSI, e-ASTROGAM and AMEGO. A possible detection of a departure of the photon polarization from the standard expectations would represent an additional hint for the existence of an ALP. We also discover a peculiar feature in the VHE band, where photons at energies above ∼ 1 TeV are fully polarized because of photon-ALP interaction. A possible detection of this feature would represent a proof for the existence of an ALP, but, unfortunately, current technologies do not allow yet to detect photon polarization up to so high energies.

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Searching for Axion-Like Particles with X-ray Polarimeters

Cited by 30 publications

References 45 publications

Superradiance in String Theory

Superradiance in String Theory

Astrophysical Searches and Constraints on Ultralight Bosonic Dark Matter

Photon-ALP oscillations inducing modifications to photon polarization

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