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arXiv · 1707.05238

Molecular gas in three z~7 quasar host galaxies

Bram Venemans·Fabian Walter·Roberto Decarli·Carl Ferkinhoff·Axel Weiss·Joseph Findlay·Richard McMahon·Will Sutherland·Rowin Meijerink
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Abstract

We present ALMA band 3 observations of the CO(6-5), CO(7-6), and [CI] 369micron emission lines in three of the highest redshift quasar host galaxies at 6.6 2", or >14kpc) CO emission in all three quasar hosts. In two sources, we detect the continuum emission around 400micron (rest-frame), and in one source we detect [CI] at low significance. We derive molecular gas reservoirs of (1-3)x10^10 M_sun in the quasar hosts, i.e. approximately only 10 times the mass of their central supermassive black holes. The extrapolated [CII]-to-CO(1-0) luminosity ratio is 2500-4200, consistent with measurements in galaxies at lower redshift. The detection of the [CI] line in one quasar host galaxy and the limit on the [CI] emission in the other two hosts enables a first characterization of the physical properties of the interstellar medium in z~7 quasar hosts. In the sources, the derived global CO/[CII]/[CI] line ratios are consistent with expectations from photodissociation regions (PDR), but not X-ray dominated regions (XDR). This suggest that quantities derived from the molecular gas and dust emission are related to ongoing star-formation activity in the quasar hosts, providing further evidence that the quasar hosts studied here harbor intense starbursts in addition to their active nucleus.

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Bram Venemans, Fabian Walter, Roberto Decarli, Carl Ferkinhoff, Axel Weiss, Joseph Findlay, Richard McMahon, Will Sutherland, Rowin Meijerink. 2017-07-17. Molecular gas in three z~7 quasar host galaxies. https://doi.org/10.3847/1538-4357%2Faa81cb

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