Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Soft X-rays from disk galaxy halos, Ly-alpha emission from forming
  galaxies, and the z~1 Tully-Fisher relation   Extended, soft X-ray emission from the halo of a very large disk galaxy has
been detected out to r~20-40 kpc. The luminosity and surface brightness
distribution is in very good agreement with predictions by recent, cosmological
galaxy formation models. Predictions of Ly-alpha emission, associated with
``cold'' accretion of filamentary gas onto galaxies, are presented. In
particular these predictions are compared to the properties of a recently
detected Ly-alpha ``blob'', which shows no obvious continuum counter-part in
any of 12 broad-bands, from X-rays (Chandra) to infrared (Spitzer). Finally,
the predicted evolution of the Tully-Fisher relation, going from z=0 to 1, is
discussed in relation to recent observations.

19
The categories of this paper are: eess
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph