An ALMA multi-line survey of the interstellar medium of the redshift 7.5
  quasar host galaxy J1342+0928
  We use ALMA observations of the host galaxy of the quasar ULAS-J1342+0928 at
z=7.54 to study the dust continuum and far infrared lines emitted from its
interstellar medium. The Rayleigh-Jeans tail of the dust continuum is well
sampled with eight different spectral setups, and from a modified black body
fit we obtain an emissivity coefficient of beta=1.85+-0.3. Assuming a standard
dust temperature of 47 K we derive a dust mass of Mdust=0.35x10^8 Msol and a
star formation rate of 150+-30 Msol/yr. We have >4sigma detections of the
[CII]_158, [OIII]_88 and [NII]_122 atomic fine structure lines and limits on
the [CI]_369, [OI]_146 and [NII]_205 emission. We also report multiple limits
of CO rotational lines with Jup >= 7, as well as a tentative 3.3sigma detection
of the stack of four CO lines (Jup=11, 10, 8, 7). We find line deficits that
are in agreement with local ultra luminous infrared galaxies. Comparison of the
[NII]_122 and [CII]_158 lines indicates that the [CII]_158 emission arises
predominantly from the neutral medium, and we estimate that the
photo-disassociation regions in J1342+0928 have densities <~5x10^4cm^-3. The
data suggest that ~16% of hydrogen is in ionized form and that the HII regions
have high electron densities of n_e>180 cm^-3. Our observations favor a low
gas-to-dust ratio of <100 and a metallicity of the interstellar medium
comparable to the Solar value. All the measurements presented here suggest that
the host galaxy of J1342+0928 is highly enriched in metal and dust, despite
being observed just 680 Myr after the Big Bang.
