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Register a new userDetecting Axion-like Dark Matter with Linearly Polarized Pulsar Light
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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 $sim 10^{-13}$ GeV$^{-1}$ for axion mass $m_a sim 10^{-22}-10^{-20}$ eV, given the current measurement accuracy. An exclusion limit stronger than CAST ($ sim 10^{-10}$ GeV$^{-1}$) and SN1987A ($ sim 10^{-11}$ GeV$^{-1}$) could be extended up to $m_a sim 10^{-18}$ eV and $sim 10^{-19}$ eV, respectively.
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We consider the search for axion-like particles (ALPs) by using time series data of the polarization angle of the light. If the condensation of an ALP plays the role of dark matter, the polarization plane of the light oscillates as a function of time and we may be able to detect the signal of the ALP by continuously observing the polarization. In particular, we discuss that the analysis of the Fourier-transformed data of the time-dependent polarization angle is powerful to find the signal of the ALP dark matter. We pay particular attention to the light coming from astrophysical sources such as protoplanetary disks, supernova remnants, the foreground emission of the cosmic microwave background, and so on. We show that, for the ALP mass of $sim 10^{-22}$--$10^{-19} {rm eV}$, ALP searches in the Fourier space may reach the parameter region which is unexplored by other searches yet.
Analytic arguments and numerical simulations show that bosonic ultra-light dark matter (ULDM) would form cored density distributions (`solitons) at the center of galaxies. ULDM solitons offer a promising way to exclude or detect ULDM by looking for a distinctive feature in the central region of galactic rotation curves. Baryonic contributions to the gravitational potential pose an obstacle to such analyses, being (i) dynamically important in the inner galaxy and (ii) highly non-spherical in rotation-supported galaxies, resulting in non-spherical solitons. We present an algorithm for finding the ground state soliton solution in the presence of stationary non-spherical background baryonic mass distribution. We quantify the impact of baryons on the predicted ULDM soliton in the Milky Way and in low surface-brightness galaxies from the SPARC database.
Axion-like particles are dark matter candidates motivated by the Peccei-Quinn mechanism and also occur in effective field theories where their masses and photon couplings are independent. We estimate the dispersion of circularly polarized photons in a background of oscillating axion-like particles (ALPs) with the standard $g_{agamma},a,F_{mu u}tilde F^{mu u}/4$ coupling to photons. This leads to birefringence or rotation of linear polarization by ALP dark matter. Cosmic microwave background (CMB) birefringence limits $Delta alpha lesssim (1.0)^circ$ enable us to constrain the axion-photon coupling $g_{agamma} lesssim 10^{-17}-10^{-12},{rm GeV}^{-1}$, for ultra-light ALP masses $m_a sim 10^{-27} - 10^{-24}$ eV. This improves upon previous axion-photon coupling limits by up to four orders of magnitude. Future CMB observations could tighten limits by another one to two orders.
In this paper, we propose a generalized natural inflation (GNI) model to study axion-like particle (ALP) inflation and dark matter (DM). GNI contains two additional parameters $(n_1, n_2)$ in comparison with the natural inflation, that make GNI more general. The $n_1$ build the connection between GNI and other ALP inflation model, $n_2$ controls the inflaton mass. After considering the cosmic microwave background and other cosmological observation limits, the model can realize small-field inflation with a wide mass range, and the ALP inflaton considering here can serve as the DM candidate for certain parameter spaces.
Astrophysical observations indicate that there is roughly five times more dark matter in the Universe than ordinary baryonic matter, with an even larger amount of the Universes energy content due to dark energy. So far, the microscopic properties of these dark components have remained shrouded in mystery. In addition, even the five percent of ordinary matter in our Universe has yet to be understood, since the Standard Model of particle physics lacks any consistent explanation for the predominance of matter over antimatter. Inspired by these central problems of modern physics, we present here a direct search for interactions of antimatter with dark matter, and place direct constraints on the interaction of ultra-light axion-like particles $-$ one of the dark-matter candidates $-$ and antiprotons. If antiprotons exhibit a stronger coupling to these dark-matter particles than protons, such a CPT-odd coupling could provide a link between dark matter and the baryon asymmetry in the Universe. We analyse spin-flip resonance data acquired with a single antiproton in a Penning trap [Smorra et al., Nature 550, 371 (2017)] in the frequency domain to search for spin-precession effects from ultra-light axions with a characteristic frequency governed by the mass of the underlying particle. Our analysis constrains the axion-antiproton interaction parameter $f_a/C_{overline{p}}$ to values greater than $0.1$ to $0.6$ GeV in the mass range from $2 times 10^{-23}$ to $4 times 10^{-17},$eV/$c^2$, improving over astrophysical antiproton bounds by up to five orders of magnitude. In addition, we derive limits on six combinations of previously unconstrained Lorentz-violating and CPT-violating terms of the non-minimal Standard Model Extension.
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