Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Analyzing the Flux Anomalies of the Large-Separation Lensed Quasar SDSS
  J1029+2623   Using a high resolution radio image, we successfully resolve the two fold
image components B and C of the quasar lens system SDSS J1029+2623. The flux
anomalies associated with these two components in the optical regime persist,
albeit less strongly, in our radio observations, suggesting that the cluster
must be modeled by something more than a single central potential. We argue
that placing substructure close to one of the components can account for a flux
anomaly with negligible changes in the component positions. Our best fit model
has a substructure mass of ~10^8 solar masses up to the mass-sheet degeneracy,
located roughly 0.1 arcsecs West and 0.1 arcsecs North of component B. We
demonstrate that a positional offset between the centers of the source
components can explain the differences between the optical and radio flux
ratios.

2
The categories of this paper are: math
30
The categories of this paper are: q-alg
25
The categories of this paper are: patt-sol
20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn