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 β = 1.85 ± 0.3. Assuming a standard dust temperature of 47K we derive a dust mass of Mdust= 0.35 × 108Mo and a star formation rate of 150 ± 30Mo yr-1. We have > 4δ detections of the [CII]158μm, [OIII]88μmand [NII]122μmatomic fine structure lines and limits on the [CI]369μm, [OI]146μmand [NII]205μmemission. We also report multiple limits of CO rotational lines with Jup 7, as well as a tentative 3.3μ detection of the stack of four CO lines (Jup = 11; 10; 8 and 7). We find line deficits that are in agreement with local ultra luminous infrared galaxies. Comparison of the [NII]122μmand [CII]158μmlines indicates that the [CII]158 μm emission arises predominantly from the neutral medium, and we estimate that the photo-disassociation regions in J1342+0928 have densities . 5 ≲ 104 cm-3. The data suggest that ∼ 16% of hydrogen is in ionized form and that the HII regions have high electron densities of ne > 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.
|Original language||English (US)|
|State||Published - Jun 20 2019|
- Emission Lines-Galaxies: Individual (ULAS J1342+0928)
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