Beschreibung:
<jats:title>Abstract</jats:title>
<jats:p>We present a census of neutral gas in the Milky Way disk and halo down to limiting column densities of <jats:italic>N</jats:italic>(H <jats:sc>i</jats:sc>) ∼ 10<jats:sup>14</jats:sup> cm<jats:sup>−2</jats:sup> using measurements of H <jats:sc>i</jats:sc> Lyman series absorption from the Far Ultraviolet Spectroscopic Explorer. Our results are drawn from an analysis of 25 AGN sight lines spread evenly across the sky with Galactic latitude ∣<jats:italic>b</jats:italic>∣ ≳ 20°. By simultaneously fitting multi-component Voigt profiles to 11 Lyman series absorption transitions covered by FUSE (Ly<jats:italic>β</jats:italic>–Ly<jats:italic>μ</jats:italic>) plus HST measurements of Ly<jats:italic>α</jats:italic>, we derive the kinematics and column densities of a sample of 152 H <jats:sc>i</jats:sc> absorption components. While saturation prevents accurate measurements of many components with column densities 17 ≲ log <jats:italic>N</jats:italic>(H <jats:sc>i</jats:sc>) ≲ 19, we derive robust measurements at log <jats:italic>N</jats:italic>(H <jats:sc>i</jats:sc>) ≲ 17 and log <jats:italic>N</jats:italic>(H <jats:sc>i</jats:sc>) ≳ 19. We derive the first ultraviolet H <jats:sc>i</jats:sc> column density distribution function (CDDF) of the Milky Way, both globally and for low-velocity (ISM), intermediate-velocity clouds (IVCs), and high-velocity clouds (HVCs). We find that IVCs and HVCs show statistically indistinguishable CDDF slopes, with <jats:italic>β</jats:italic>
<jats:sub>IVC</jats:sub> = <jats:inline-formula>
<jats:tex-math>
<?CDATA $-{1.01}_{-0.14}^{+0.15}$?>
</jats:tex-math>
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<mml:mo>−</mml:mo>
<mml:msubsup>
<mml:mrow>
<mml:mn>1.01</mml:mn>
</mml:mrow>
<mml:mrow>
<mml:mo>−</mml:mo>
<mml:mn>0.14</mml:mn>
</mml:mrow>
<mml:mrow>
<mml:mo>+</mml:mo>
<mml:mn>0.15</mml:mn>
</mml:mrow>
</mml:msubsup>
</mml:math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac1b9fieqn1.gif" xlink:type="simple" />
</jats:inline-formula> and <jats:italic>β</jats:italic>
<jats:sub>HVC</jats:sub> = <jats:inline-formula>
<jats:tex-math>
<?CDATA $-{1.05}_{-0.06}^{+0.07}$?>
</jats:tex-math>
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<mml:mo>−</mml:mo>
<mml:msubsup>
<mml:mrow>
<mml:mn>1.05</mml:mn>
</mml:mrow>
<mml:mrow>
<mml:mo>−</mml:mo>
<mml:mn>0.06</mml:mn>
</mml:mrow>
<mml:mrow>
<mml:mo>+</mml:mo>
<mml:mn>0.07</mml:mn>
</mml:mrow>
</mml:msubsup>
</mml:math>
<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac1b9fieqn2.gif" xlink:type="simple" />
</jats:inline-formula>. Overall, the CDDF of the Galactic disk and halo appears shallower than that found by comparable extragalactic surveys, suggesting a relative abundance of high column density gas in the Galactic halo. We derive the sky-covering fractions as a function of H <jats:sc>i</jats:sc> column density, finding an enhancement of IVC gas in the northern hemisphere compared to the south. We also find evidence for an excess of inflowing H <jats:sc>i</jats:sc> over outflowing H <jats:sc>i</jats:sc>, with −0.88 ± 0.40 <jats:italic>M</jats:italic>
<jats:sub>⊙</jats:sub> yr<jats:sup>−1</jats:sup> of HVC inflow versus ≈0.20 ± 0.10 <jats:italic>M</jats:italic>
<jats:sub>⊙</jats:sub> yr<jats:sup>−1</jats:sup> of HVC outflow, confirming an excess of inflowing HVCs seen in UV metal lines.</jats:p>