Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Estimation of Peculiar Velocity from the Inverse Tully-Fisher Relation   We present a method for deriving a smoothed estimate of the peculiar velocity
field of a set of galaxies with measured circular velocities $\eta\equiv {\rm
log} \Delta v$ and apparent magnitudes $m$. The method is based on minimizing
the scatter of a linear inverse Tully-Fisher relation $\eta= \eta(M)$ where the
absolute magnitude of each galaxy is inferred from its redshift $z$, corrected
by a peculiar velocity field, $M \propto m - 5\log(z-u)$. We describe the
radial peculiar velocity field $u({\bf z})$ in terms of a set of orthogonal
functions which can be derived from any convenient basis set; as an example we
take them to be linear combinations of low order spherical harmonic and
spherical Bessel functions. The model parameters are then found by maximizing
the likelihood function for measuring a set of observed $\eta$. The predicted
peculiar velocities are free of Malmquist bias in the absence of
multi-streaming, provided no selection criteria are imposed on the measurement
of circular velocities. This procedure can be considered as a generalized
smoothing algorithm of the peculiar velocity field, and is particularly useful
for comparison to the smoothed gravity field derived from full-sky galaxy
redshift catalogs such as the IRAS surveys. We demonstrate the technique using
a catalog of ``galaxies" derived from an N-body simulation. Increasing the
resolution of the velocity smoothing beyond a certain level degrades the
correlation of fitted velocities against the velocities calculated from linear
theory methods, which have finite resolution,

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The categories of this paper are: comp-gas
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-th
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The categories of this paper are: atom-ph
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The categories of this paper are: math
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The categories of this paper are: mtrl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: eess
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The categories of this paper are: adap-org
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The categories of this paper are: funct-an
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The categories of this paper are: nlin
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The categories of this paper are: q-fin
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The categories of this paper are: acc-phys
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The categories of this paper are: stat