Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: CO line width and the black hole -- bulge relationship at high redshift   Recently, it has been suggested that the CO line width (FWHM(CO)) is a
surrogate for the bulge velocity dispersion ($\sigma$) of the host galaxies of
high-redshift quasars, and the black hole -- bulge ($M_{BH}-\sigma$) relation
obtained with this assumption departs significantly from the $M_{BH}-\sigma$
relation in the local universe. In this study, we first present an
investigation of the correlation between the CO line width and the bulge
velocity dispersion using a sample of 33 nearby Seyfert galaxies. We find that
the formula adopted in previous studies, $\sigma=\rm{FWHM(CO)}/2.35$, is
generally not a good approximation. Using it, one may underestimate the value
of bulge velocity dispersion significantly when the CO line is narrower than
400 $km s^{-1}$. By involving the galactic inclination angle $i$ as an
additional parameter, we obtain a tight correlation between the
inclination-corrected CO line width and the bulge velocity dispersion, namely,
$\rm {FWHM(CO)}/\sin i=-67.16\pm80.18+(3.62\pm0.68)\sigma$. Using this new
relation, we can better estimate the bulge velocity dispersion from the CO line
width if the galactic inclination is known. We apply this new relation to nine
high-redshift quasars with CO line detections and find that they are consistent
with the local $M_{BH}-\sigma$ relation if their inclination angles are around
$15^o$. The possible smaller inclinations of the high-redshift quasars are
preferred because of their relatively greater likelihood of detection, and are
also consistent with their relatively smaller CO line widths compared to
submillimeter galaxies (SMGs) at high redshift having a similar total amount of
molecular gas. Future observations are needed to confirm these results.

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The categories of this paper are: dg-ga
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The categories of this paper are: eess
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The categories of this paper are: nlin
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The categories of this paper are: comp-gas
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-ex
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The categories of this paper are: adap-org
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The categories of this paper are: solv-int
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The categories of this paper are: econ
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The categories of this paper are: chem-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: alg-geom
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The categories of this paper are: cs
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The categories of this paper are: mtrl-th
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The categories of this paper are: atom-ph
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The categories of this paper are: plasm-ph