Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Fingerprints of Black Holes - Shadows and their Degeneracies   We show that, away from the axis of symmetry, no continuous degeneration
exists between the shadows of observers at any point in the exterior region of
any Kerr-Newman black hole spacetime of unit mass. Therefore, except possibly
for discrete changes, an observer can, by measuring the black holes shadow,
determine the angular momentum and the charge of the black hole under
observation, as well as the observer's radial position and angle of elevation
above the equatorial plane. Furthermore, his/her relative velocity compared to
a standard observer can also be measured. On the other hand, the black hole
shadow does not allow for a full parameter resolution in the case of a
Kerr-Newman-Taub-NUT black hole, as a continuous degeneration relating specific
angular momentum, electric charge, NUT charge and elevation angle exists in
this case.

23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
13
The categories of this paper are: quant-ph
35
The categories of this paper are: mtrl-th
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
18
The categories of this paper are: econ
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs