5,606 research outputs found
Note on a new parametrization for testing the Kerr metric
We propose a new parametrization for testing the Kerr nature of astrophysical
black hole candidates. The common approaches focus on the attempt to constrain
possible deviations from the Kerr solution described by new terms in the
metric. Here we adopt a different perspective. The mass and the spin of a black
hole make the spacetime curved and we want to check whether they do it with the
strength predicted by general relativity. As an example, we apply our
parametrization to the black hole shadow, an observation that may be possible
in a not too distant future.Comment: 8 pages, 3 figure
Entanglement entropy in long-range harmonic oscillators
We study the Von Neumann and R\'enyi entanglement entropy of long-range
harmonic oscillators (LRHO) by both theoretical and numerical means. We show
that the entanglement entropy in massless harmonic oscillators increases
logarithmically with the sub-system size as .
Although the entanglement entropy of LRHO's shares some similarities with the
entanglement entropy at conformal critical points we show that the R\'enyi
entanglement entropy presents some deviations from the expected conformal
behavior. In the massive case we demonstrate that the behavior of the
entanglement entropy with respect to the correlation length is also logarithmic
as the short range case.Comment: Published version, 5 figure
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