Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gravitational lensing by exotic objects   This paper reviews a phenomenological approach to the gravitational lensing
by exotic objects such as the Ellis wormhole lens, where exotic lens objects
may follow a non-standard form of the equation of state or may obey a modified
gravity theory. A gravitational lens model is proposed in the inverse powers of
the distance, such that the Schwarzschild lens and exotic lenses can be
described in a unified manner as a one parameter family. As observational
implications, the magnification, shear, photo-centroid motion and time delay in
this lens model are discussed.

37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph