Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optimized supernova constraints on dark energy evolution   A model-independent method to study the possible evolution of dark energy is
presented. Optimal estimates of the dark energy equation of state w are
obtained from current supernovae data from Riess et al. (2004) following a
principal components approach. We assess the impact of varying the number of
piecewise constant estimates of w using a model selection method, the Bayesian
information criterion, and compare the most favored models with some
parametrizations commonly used in the literature. Although data seem to prefer
a cosmological constant, some models are only moderately disfavored by our
selection criterion: a constant w, w linear in the scale factor, w linear in
redshift and the two-parameter models introduced here. Among these, the models
we find by optimization are slightly preferred. However, current data do not
allow us to draw a conclusion on the possible evolution of dark energy.
Interestingly, the best fits for all varying-w models exhibit a w<-1 at low
redshifts.

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The categories of this paper are: acc-phys
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The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
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The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
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The categories of this paper are: dg-ga
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The categories of this paper are: ao-sci
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-fin
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The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
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The categories of this paper are: alg-geom
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The categories of this paper are: solv-int