English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We propose a new method to determine the physical parameters of Kerr blackholes (namely, specific angular momentum $a$, inclination angle $i$, anddistance $D$ from an observer) only from the shadow's information such as thesize and shape. Key points in our method are (i) to treat the distance as afree parameter, (ii) to expand the shadow's outline as a Fourier series, and(iii) to construct principal components from the Fourier coefficients. Thesepoints enable us to obtain a one-to-one mapping between three principalcomponents, being observables characterizing the size and deviation of shadow'sshape from a circular disk, and the values of three parameters ($D/M, a/M, i$),where $M$ is the mass of black hole. Our method is applicable to various typeof black holes and even to ones with accretion disks.

Determining parameters of Kerr black holes at finite distance by shadow observation