185 research outputs found
Constraining the Existence of Axion Clouds in M87* with Closure Trace Analyses
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
particles (ALPs) are candidate beyond-standard-model particles that can form
such clouds around supermassive black holes (SMBHs) and impact the polarization
signal in a similar fashion to Faraday rotation via axion-photon coupling.
Prior efforts have used polarized images from the Event Horizon Telescope (EHT)
M87 2017 observations to limit the dimensionless axion-photon coupling to
previously unexplored regions. However, with the novel calibration-insensitive
quantities, closure traces and conjugate closure trace products, it is possible
to constrain the existence of axion clouds while avoiding the dominant sources
of systematic uncertainties, e.g., station gains and polarization leakages. We
utilize a simple geometric model for the polarization map of M87* to fit the
model parameters with both simulated and real data sets and reach a comparable
level of constraint in the accuracy with which an axion cloud may be excluded
in M87. Future applications of our approach include subsequent M87* and Sgr A*
observations by EHT and next-generation EHT (ngEHT) are expected to produce
stronger constraints across a wider range of axion and ALP masses. Because it
does not require imaging, closure trace analyses may be applied to target AGN
for which imaging is marginal, extending the number of SMBHs from which axion
limits may be obtained significantly.Comment: 12 pages, 11 figures, 1 table, submitted to Ap
Effective equidistribution for some one parameter unipotent flows
We prove effective equidistribution theorems, with polynomial error rate, for
orbits of the unipotent subgroups of in
arithmetic quotients of and
.
The proof is based on the use of a Margulis function, tools from incidence
geometry, and the spectral gap of the ambient space.Comment: 128 page
Quantitative equidistribution and the local statistics of the spectrum of a flat torus
We show that pair correlation function for the spectrum of a flat
2-dimensional torus satisfying an explicit Diophantine condition agrees with
those of a Poisson process with a polynomial error rate.
The proof is based on a quantitative equidistribution theorem and tools from
geometry of numbers.Comment: 47 page
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