Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Unbiased Estimate of Dark Energy Density from Type Ia Supernova Data   Type Ia supernovae (SNe Ia) are currently the best probes of the dark energy
in the universe. To constrain the nature of dark energy in a model-independent
manner, we allow the density of dark energy, $\rho_X(z)$, to be an arbitrary
function of redshift. Using simulated data from a space-based supernova pencil
beam survey, we find that by optimizing the number of parameters used to
parametrize the dimensionless dark energy density,
$f(z)=\rho_X(z)/\rho_X(z=0)$, we can obtain an unbiased estimate of both f(z)
and $\Omega_m$ (assuming a flat universe and that the weak energy condition is
satisfied). A plausible supernova pencil beam survey (with a square degree
field of view and for an observational duration of one year) can yield about
2000 SNe Ia with $0\le z \le 2$. Such a survey in space would yield SN peak
luminosities with a combined intrinsic and observational dispersion of $\sigma
(m_{int})=0.16$ mag. We find that for such an idealized survey, $\Omega_m$ can
be measured to 10% accuracy, and f(z) can be estimated to $\sim$ 20% to $z \sim
1.5$, and $\sim$ 20-40% to $z \sim 2$, depending on the time dependence of the
true dark energy density. Dark energy densities which vary more slowly can be
more accurately measured. For the anticipated SNAP mission, $\Omega_m$ can be
measured to 14% accuracy, and f(z) can be estimated to $\sim$ 20% to $z \sim
1.2$. Our results suggest that SNAP may gain much sensitivity to the
time-dependence of f(z) and $\Omega_m$ by devoting more observational time to
the central pencil beam fields to obtain more SNe Ia at z>1.2. We also find
that Monte Carlo analysis gives a more accurate estimate of the dark energy
density than the maximum likelihood analysis. (abridged)

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The categories of this paper are: nlin
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The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci
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The categories of this paper are: acc-phys
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The categories of this paper are: q-alg
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-th
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The categories of this paper are: math
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The categories of this paper are: eess
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The categories of this paper are: stat
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The categories of this paper are: chao-dyn
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The categories of this paper are: cs
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-th
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The categories of this paper are: adap-org
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The categories of this paper are: mtrl-th