Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evidence for an outer disk in the Prototype `Compact Elliptical' Galaxy
  M32   M32 is the prototype for the relatively rare class of galaxies referred to as
`compact ellipticals'. It has been suggested that M32 may be a tidally
disturbed r^(1/4) elliptical galaxy, or the remnant bulge of a disk-stripped
early-type spiral galaxy. This paper reveals that the surface brightness
profile, the velocity dispersion measurements, and the estimated supermassive
black hole mass in M32 are inconsistent with the galaxy having, and probably
ever having had, an r^(1/4) light profile. Instead, the radial surface
brightness distribution of M32 resembles an almost perfect (bulge + exponential
disk) profile, which is accompanied by a marked increase in the ellipticity
profile and an associated change in the position angle profile where the `disk'
starts to dominate. Compelling evidence that this bulge/disk interpretation is
accurate comes from the best-fitting r^(1/n) bulge model which has a Sersic
index n=1.5, in agreement with the recently discovered relation between a
bulge's Sersic index and the mass of its supermassive black hole. An index n>4
would also be inconsistent with the stellar velocity dispersion of M32. The
bulge-to-disk size ratio r_e /h equals 0.20, and the logarithm of the
bulge-to-disk luminosity ratio log(B/D) equals 0.22, typical of lenticular
galaxies. The effective radius of the bulge is 27" (~100 pc), while the
scale-length of the disk is less well determined: due to possible tidal-
stripping of the outer profile beyond 220-250", the scale-length may be as
large as 1.3 kpc. M32 is a relatively face-on, nucleated, dwarf galaxy with a
low surface brightness disk and a high surface brightness bulge. This finding
brings into question the existence of the compact elliptical class of galaxies.

34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys