Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Constraints on Intracluster Gas Bulk Motions in Clusters of Galaxies
  with ASCA   The recent detection of Doppler shifts of X-ray spectral lines in the
intracluster gas of the Centaurus and Perseus clusters of galaxies with ASCA
has raised the question of the frequency of such velocity gradients and their
relation to other cluster properties. To address this and improve the sample of
ICM velocity gradient candidates we carried out a systematic search of the ASCA
archive for clusters with suitable observing conditions that allow full
azimuthal mapping of gas velocities near the central regions. Here we present
the results of the azimuthal velocity distribution of a sample consisting of
the best" observed clusters for velocity analysis. Our sample encompasses
clusters with different physical and morphological characteristics, including
both well behaved "cooling flow" and dynamically active clusters. The gas
temperatures of the clusters in our sample range from 1.4 keV to 6.3 keV. We
find velocity substructures in ~ 15% of the clusters in our sample on the order
of a few x 1E3 km/s. The significance of the velocity gradients' is greater
than 99% in Abell 576 and RXJ0419.6+0225, the clusters where velocity gradients
are most significant. The velocity gradients are consistent with transitory
and/or rotational bulk motion. The velocity gradients in these clusters are
unlikely to be due to projected temperature anisotropies, ASCA PSF, intrachip
gain variations, and flux contamination from other sources. Chandra images of
these clusters do not show obvious cluster alignments within the field of view
covered by ASCA. We also noticed a high frequency (~50%) of anisotropic
temperature gradients in the core of "cooling flow" clusters, suggesting the
presence of frequent dynamical activity in the core of galaxy clusters.

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The categories of this paper are: plasm-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: alg-geom
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The categories of this paper are: econ
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The categories of this paper are: acc-phys
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The categories of this paper are: solv-int
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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: supr-con
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The categories of this paper are: ao-sci
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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: quant-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: nlin