Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A fast method for computing strong-lensing cross sections: Application
  to merging clusters   Strong gravitational lensing by irregular mass distributions, such as galaxy
clusters, is generally not well quantified by cross sections of analytic mass
models. Computationally expensive ray-tracing methods have so far been
necessary for accurate cross-section calculations. We describe a fast,
semi-analytic method here which is based on surface integrals over
high-magnification regions in the lens plane and demonstrate that it yields
reliable cross sections even for complex, asymmetric mass distributions. The
method is faster than ray-tracing simulations by factors of $\sim30$ and thus
suitable for large cosmological simulations, saving large amounts of computing
time. We apply this method to a sample of galaxy cluster-sized dark matter
haloes with simulated merger trees and show that cluster mergers approximately
double the strong-lensing optical depth for lens redshifts
$z_\mathrm{l}\gtrsim0.5$ and sources near $z_\mathrm{s} = 2$. We believe that
this result hints at one possibility for understanding the recently detected
high arcs abundance in clusters at moderate and high redshifts, and is thus
worth further studies.

12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
23
The categories of this paper are: solv-int
15
The categories of this paper are: nucl-ex
5
The categories of this paper are: gr-qc
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci