Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Tidal Streams and Low Mass Companions of M31   We have imaged the extended HI environment of M31 with an unprecedented
combination of high resolution and sensitivity. We detect a number of distinct
High Velocity Cloud components associated with M31. A sub-set of the features
within 30 kpc appear to be tidal in origin. A filamentary ``halo'' component is
concentrated at the M31 systemic velocity and appears to extend into a
``bridge'' connecting M31 and M33. This may represent condensation in coronal
gas. A population of discrete clouds is detected out to radii of about 150 kpc.
Discrete cloud line-widths are correlated with HI mass and are consistent with
a 100:1 ratio of dark to HI mass. These may be the gaseous counterparts of
low-mass dark-matter satellites. The combined distribution of M31's HVC
components can be characterized by a spatial Gaussian of 55 kpc dispersion and
yields an N_HI distribution function which agrees well with that of low
red-shift QSOs.

31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
19
The categories of this paper are: eess
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
3
The categories of this paper are: physics
25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex