Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Investigation of the Contamination of the Gould (2003) Halo Sample   A recent astroph posting argued that the Gould (2003a) halo sample is
substantially contaminated with thick-disk stars, which would then ``wash out''
any signature of granularity in the halo velocity distribution due to streams.
If correct, this would imply that the limits placed by Gould (2003b) on streams
are not valid. Here I investigate such contamination using six different
indicators: (1) morphology of the underlying reduced proper motion diagram used
to select halo stars; (2) comparison of kinematic and parallax-based distance
scales; (3) comparison of derived halo parameters for the Gould (2003a) sample
with other determinations; (4) a precision color-color diagram for a random
subsample; (5) the 3-dimensional velocity distribution of a random subsample;
(6) metallicity distribution versus kinematic cuts on a random subsample. I
estimate that the contamination is of order 2%. Thus, the upper limits on the
density of nearby streams derived by Gould (2003b) remain valid. In particular,
at 95% confidence, no more than 5% of local halo stars (within about 300 pc)
are in any one coherent stream. Determining whether or not this local
measurement is consistent with CDM remains an outstanding question.

32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
3
The categories of this paper are: physics
9
The categories of this paper are: nlin