Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Galaxy groups in the 2dF galaxy redshift survey: A Compactness Analysis
  of Groups   A comprehensive study on compactness has been carried out on the 2dF Galaxy
Group Catalogue constructed by Merch\'an & Zandivarez. The compactness indexes
defined in this work take into account different geometrical constraints in
order to explore a wide range of possibilities. Our results show that there is
no clear distinction between groups with high and low level of compactness when
considering particular properties as the radial velocity dispersion, the
relative fraction of galaxies per spectral type and luminosity functions of
their galaxy members.
  Studying the trend of the fraction of galaxies per spectral type as a
function of the dimensionless crossing time some signs of dynamical evolution
are observed. From the comparison with previous works on compactness we realize
that special care should be taken into account for some compactness criteria
definitions in order to avoid possible biases in the identification.

15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
23
The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
4
The categories of this paper are: cond-mat
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
19
The categories of this paper are: eess