Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dark halo properties from rotation curves   We study a large set of high spatial resolution optical rotation curves of
galaxies with the goal of determining the model parameters for a disk embedded
within a CDM halo that we model either with a NFW profile or pseudo-isothermal
profile. We show that parameter degeneracies present in lower resolution data
are lifted at these higher resolutions. 34% of the galaxies do not have a
meaningful fit when using the NFW profile and 32% when using the
pseudoisothermal profile, however only 14% do not have a meaningful fit in
either model. In both models we find correlations between the disk baryon
fraction $f_d$ and the spin parameter of the halo $\lambda'$, between $f_d$ and
the dark halo mass $M_{200}$, and between $M_{200}$ and the concentration
parameter $c$. We show that the distribution of the concentration parameters
$c$, for a NFW halo, is in good agreement with CDM predictions; no significant
galaxy population is found with very low values of $c$. The overall
distribution of $\lambda'$ is in good agreement with theoretical predictions
from hierarchical tidal torque theory. The whole sample is also well fitted by
a pseudo-isothermal dark halo with a core, but the size of the core is rather
small (for 70% of the sample the core size is less than 2 kpc). Thus we
conclude that the profile of dark matter is steep ($r^{-1}$ or steeper) down to
this radius; large dark matter cores (and therefore very low dark matter
central densities) seem to be excluded. LSBs tend to have higher values of
$\lambda'$ for a given $f_d$ and lower values of $c$ for a given mass than
HSBs. In an appendix we give some useful formula for pseudo-isothermal profile
halos and discuss in detail the issue of parameter degeneracies.

33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
7
The categories of this paper are: hep-th
2
The categories of this paper are: math
35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
24
The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex