Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Mapping Large-Scale Gaseous Outflows in Ultraluminous Galaxies with Keck
  II ESI Spectra: Variations in Outflow Velocity with Galactic Mass   Measurements of interstellar absorption lines in 18 ultraluminous infrared
galaxies (ULIGs) have been combined with published data, in order to reassess
the dependence of galactic outflow speeds on starburst luminosity and galactic
mass. The Doppler shifts reveal outflows of relatively cool gas at $330 \pm
100$km/s. The outflow speeds increase with the star formation rate (SFR) as
roughly $v \propto SFR^{0.35}$. This result is surprising since, in the
traditional model for starburst-driven winds, these relatively cool gas clouds
are accelerated by the ram pressure of a hot, supernova-heated wind that
exhibits weak (if any) \x temperature variation with increasing galactic mass.
The lack of evidence for much hotter winds is partly a sensitivity issue; but
the outflow velocities in ultraluminous starbursts actually are consistent with
acceleration by the tepid wind, indicating a hotter component is unlikely to
dominate the momentum flux. The \nad velocities in the dwarf starburst winds do
not reach the terminal velocity of a hot wind at the measured temperature of kT
~0.73 keV. A dynamically-motivated explanation is that the dwarf starburst
winds simply lack enough momentum to accelerate the clouds to the velocity of
the hot wind. Among the subsample of starbursts with well- constrained
dynamical masses, the terminal outflow velocities approach the galactic escape
velocity. If this relation, which is similar to that observed for stellar
winds, arises from radiation pressure on dust and gas limiting the maximum
luminosity of a starburst, then feedback will be stronger in massive galaxies
than previously thought helping shape the high-mass end of the galaxy
luminosity function.

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The categories of this paper are: hep-ex
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The categories of this paper are: math
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The categories of this paper are: chao-dyn
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The categories of this paper are: nlin
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The categories of this paper are: solv-int
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The categories of this paper are: alg-geom
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The categories of this paper are: mtrl-th
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The categories of this paper are: adap-org
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The categories of this paper are: patt-sol
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The categories of this paper are: q-fin
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The categories of this paper are: atom-ph
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The categories of this paper are: eess
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The categories of this paper are: physics
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The categories of this paper are: funct-an
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-ex