Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Pulsar Timing Arrays: No longer a Blunt Instrument for Gravitational
  Wave Detection   Pulsar timing now has a rich history in placing limits on the stochastic
background of gravitational waves, and we plan soon to reach the sensitivity
where we can detect, not just place limits on, the stochastic background.
However, the capability of pulsar timing goes beyond the detection of a
background. Herein I review efforts that include single source detection,
localization, waveform recovery, a clever use of a "time-machine" effect,
alternate theories of gravity, and finally studies of the noise in our
"detector" that will allow us to tune and optimize the experiment. Pulsar
timing arrays are no longer "blunt" instruments for gravitational-wave
detection limited to only detecting an amplitude of the background. Rather they
are shrewd and tunable detectors, capable of a rich and dynamic variety of
astrophysical measurements.

2
The categories of this paper are: math
30
The categories of this paper are: q-alg
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
29
The categories of this paper are: funct-an
20
The categories of this paper are: acc-phys
14
The categories of this paper are: math-ph
16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc