Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Strong field tests of gravity with electromagnetic and gravitational
  waves   For nearly a century, Einstein's theory of gravity has been the standard
theory for describing gravitational phenomena in our universe. Along with its
successes, limitations of the theory from theoretical (e.g., singularities) and
observational (e.g., dark matter/energy) perspectives have appeared. This has
led to proposals that modify or supersede Einstein's theory, and testing these
theories against data, especially in the strong-field regime, has emerged as a
new paradigm in physics in recent years. Along with the completely new avenue
of gravitational waves, new and improved techniques based on electromagnetic
waves are being used to test general relativity (GR) ever more stringently. As
the realm beyond GR is unknown, a popular approach is to look for
theory-agnostic deviations from GR/predictions of GR. Here I describe how I
have used gravitational waves, X-rays, and black hole shadows to put
constraints on some of these theory-agnostic deviations.

21
The categories of this paper are: adap-org
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
19
The categories of this paper are: eess
0
The categories of this paper are: hep-ph
11
The categories of this paper are: hep-lat
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
17
The categories of this paper are: q-fin
18
The categories of this paper are: econ
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas