Star Formation and ISM Properties in the Host Galaxies of Three Far-infrared Luminous Quasars at z approx 6

Abstract

We present Karl G. Jansky Very Large Array observations of the CO (2−1)line emission toward three far-infrared luminous quasars at z∼6: SDSS J231038.88+185519.7 and SDSS J012958.51−003539.7 with ∼0 6 resolution and SDSS J205406.42−000514.8 with ∼2 1 resolution. All three sources are detected in the CO (2−1)line emission—one source is marginally resolved, and the other two appear as point sources. Measurements of the CO (2−1)line emission allow us to calculate the molecular gas mass even without a CO excitation model. The inferred molecular gas masses are (0.8–4.3)×1010 Me. The widths and redshifts derived from the CO (2−1)line are consistent with previous CO (6−5)and [C II]measurements. We also report continuum measurements using Herschel for SDSS J231038.88+185519.7 and SDSS J012958.51−003539.7, and for SDSS J231038.88 +185519.7 data obtained at ∼140 and ∼300 GHz using the Atacama Large Millimeter/submillimeter Array. In the case of SDSS J231038.88+185519.7, we present a detailed analysis of the spectral energy distribution and derive the dust temperature (∼40 K), the dust mass (∼109 Me), the far-infrared luminosity (8–1000 μm; ∼1013 Le), and the star formation rate (2400–2700 Meyr−1). Finally, an analysis of the photodissociation regions associated with the three high-redshift quasars indicates that the interstellar medium in these sources has similar properties to local starburst galaxies.