Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Weighing a galaxy bar in the lens Q2237+0305   In the gravitational lens system Q2237+0305 the cruciform quasar image
geometry is twisted by ten degrees by the lens effect of a bar in the lensing
galaxy. This effect can be used to measure the mass of the bar. We construct a
new lensing model for this system with a power-law elliptical bulge and a
Ferrers bar. The observed ellipticity of the optical isophotes of the galaxy
leads to a nearly isothermal elliptical profile for the bulge with a total
quasar magnification of 16^{+5}_{-4}. We measure a bar mass of 7.5\pm1.5 \times
10^8 h^{-1}_{75} M_{\sun} in the region inside the quasar images.

32
The categories of this paper are: atom-ph
29
The categories of this paper are: funct-an
12
The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg
4
The categories of this paper are: cond-mat
18
The categories of this paper are: econ
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph