Three-Dimensional Aquila Rift: Magnetized HI Arch Anchored by Molecular
  Complex
  Three dimensional structure of the Aquila Rift of magnetized neutral gas is
investigated by analyzing HI and CO line data. The projected distance on the
Galactic plane of the HI arch of the Rift is ~250 pc from the Sun. The HI arch
emerges at l~ 30 deg, reaches to altitudes as high as ~ 500 pc above the plane
at l~ 350deg, and returns to the disk at l~270 deg. The extent of arch at
positive latitudes is ~1 kpc and radius is ~100 pc. The eastern root is
associated with the giant molecular cloud complex, which is the main body of
the optically defined Aquila Rift. The HI and molecular masses of the Rift are
estimated to be M_HI~1.4x10^5Msun and M_H2 ~3x10^5 Msun. Gravitational energies
to lift the gases to their heights are E_grav: HI ~1.4x10^51 and E_grav: H_2
~0.3x10^51 erg, respectively. Magnetic field is aligned along the HI arch of
the Rift, and the strength is measured to be B~10 microG using Faraday rotation
measures of extragalactic radio sources. The magnetic energy is estimated to be
E_mag~1.2x10^51 erg. A possible mechanism of formation of the Aquila Rift is
proposed in terms of interstellar magnetic inflation by a sinusoidal Parker
instability of wavelength of ~2.5 kpc and amplitude ~500 pc.
