  We present a UV spectroscopic study of ionized outflows in 21 active galactic
nuclei (AGN), observed with the HST. The targets of the SUBWAYS sample were
selected with the aim to probe the parameter space of the underexplored AGN
between the local Seyfert galaxies and the luminous quasars at high redshifts.
Our targets, spanning redshifts of 0.1-0.4 and bolometric luminosities (L_bol)
of 10^45-10^46 erg/s, have been observed with a large multi-wavelength
campaign. Here, we model the UV spectra and look for different types of AGN
outflows. We find that 60% of our targets show a presence of outflowing H I
absorption, while 40% exhibit ionized outflows seen as absorption by either C
IV, N V, or O VI. This is comparable to the occurrence of ionized outflows seen
in the local Seyfert galaxies. All UV absorption lines in the sample are
relatively narrow, with outflow velocities reaching up to -3300 km/s. We did
not detect any UV counterparts to the X-ray ultra-fast outflows (UFOs), most
likely due to their being too highly ionized. However, all SUBWAYS targets with
an X-ray UFO demonstrate the presence of UV outflows at lower velocities. We
find significant correlations between the column density (N) of the UV ions and
L_bol of the AGN, with N of H I decreasing with L_bol, while N of O VI is
increasing with L_bol. This is likely to be a photoionization effect, where
toward higher AGN luminosities, the wind becomes more ionized, resulting in
less absorption by neutral or low-ionization ions and more absorption by
high-ionization ions. In addition, we find that N of the UV ions decreases as
their outflow velocity increases. This may be explained by a mechanical power
that is evacuating the UV-absorbing medium. Our observed relations are
consistent with multiphase AGN feeding and feedback simulations indicating that
a combination of both radiative and mechanical processes are in play.
