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arXiv · 1906.08569

An ALMA multi-line survey of the interstellar medium of the redshift 7.5 quasar host galaxy J1342+0928

Mladen Novak·Eduardo Banados·Roberto Decarli·Fabian Walter·Bram Venemans·Marcel Neeleman·Emanuele Paolo Farina·Chiara Mazzucchelli·Chris Carilli·Xiaohui Fan·Hans-Walter Rix·Feige Wang
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Abstract

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.

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Mladen Novak, Eduardo Banados, Roberto Decarli, Fabian Walter, Bram Venemans, Marcel Neeleman, Emanuele Paolo Farina, Chiara Mazzucchelli, Chris Carilli, Xiaohui Fan, Hans-Walter Rix, Feige Wang. 2019-06-20. An ALMA multi-line survey of the interstellar medium of the redshift 7.5 quasar host galaxy J1342+0928. https://doi.org/10.3847/1538-4357%2Fab2beb

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