Related papers: Observing axions through photon ring dimming of bl…
In this study, we examine the phenomenon of photon axion conversion occurring in the spacetime surrounding a black hole. Specifically, we focus on the potential existence of a magnetic field around the supermassive black hole M87*, which…
We investigate photon-axion conversion in the vicinity of rotating Kerr black holes where strong gravity traps photons on near-circular trajectories, effectively enhancing the path length. We explore the observable signatures of such a…
The axion, as a leading dark matter candidate, is the target of many ongoing and proposed experimental searches based on its coupling to photons. Ultralight axions that couple to photons can also cause polarization rotation of light, which…
The possible existence of axions in the universe introduces the intriguing possibility of photon-axion conversion in strong magnetic fields, particularly near compact objects like supermassive black holes or even naked singularity. In this…
With high spatial resolution, polarimetric imaging of a supermassive black hole, like M87$^\star$ or Sgr A$^\star$, by the Event Horizon Telescope can be used to probe the existence of ultralight bosonic particles, such as axions. Such…
We present a simple model where photons propagating in extra-galactic magnetic fields can oscillate into very light axions. The oscillations may convert some of the photons departing a distant supernova into axions, making the supernova…
A black hole image contains a bright ring of photons that have closely circled the black hole on their way from the source to the detector. Here, we study the photon ring of a rotating black hole which is pierced by a global hyper-light…
Light bosonic fields may suffer an instability around a rotating compact object. This process, known as superradiance, leads to the exponential amplification of the field around a black hole or neutron star, while the spin of the central…
General relativity predicts that black hole images ought to display a bright, thin (and as-of-yet-unresolved) ring. This "photon ring" is produced by photons that explore the strong gravity of the black hole, flowing along trajectories that…
When axion cold dark matter interacts with a static magnetic field, it can be converted to photons with energy near the axion's mass. Classical analysis shows that incorporating a resonant cavity significantly enhances this conversion rate,…
Recently, the image of a Schwarzschild black hole with an accretion disk has been revisited, and it showed that the "photon ring", defined as highly bent light rays that intersect the disk plane more than twice, is extremely narrow and…
Light axions ($m_a \lesssim 10^{-10}$ eV) can form dense clouds around rapidly rotating astrophysical black holes via a mechanism known as rotational superradiance. The coupling between axions and photons induces a parametric resonance,…
We consider the dimming of photons from high redshift type 1a supernovae by mixing with a pseudoscalar axion field in the intergalactic medium. We model the electron density using a lognormal probability distribution and assume frozen in…
Black-hole superradiance has been used to place very strong bounds on a variety of models of ultralight bosons such as axions, new light scalars, and dark photons. It is common lore to believe that superradiance bounds are broadly model…
Light orbiting an accreting black hole may impact the disk or jet multiple times before escaping to the observer, at a variety of angles with respect to the local magnetic field. In this letter, we characterize the imprints of these long…
Due to their high magnetic fields and plasma densities, pulsars provide excellent laboratories for tests of beyond Standard Model (BSM) physics. When axions or axion-like particles (ALPs) approach closely enough to pulsars, they can be…
Simulated images of a black hole surrounded by optically thin emission typically display two main features: a central brightness depression and a narrow, bright "photon ring" consisting of strongly lensed images superposed on top of the…
It is known that a coherently oscillating axion field is a candidate of the dark matter. In the presence of the oscillating axion, the photon can be resonantly produced through the parametric amplification. In the universe, there also exist…
The impact of axion-like particles on the light polarization around the horizon of suppermassive black hole (SMBH) is discussed in the light of the latest polarization measurement of the Event Horizon Telescope (EHT). We investigate…
Black holes can amplify incoming bosonic waves via rotational superradiance, inducing bound states of ultralight bosons around them. This phenomenon has the potential to confine the parameter spaces of new bosons. Axions and axion-like…