Star formation and ISM properties in host galaxies of three far-infrared luminous quasars at z ∼ 6

We present Karl G. Jansky Very Large Array (VLA) observations of the CO (2−1) line emission towards three far-infrared luminous quasars at z ∼ 6: SDSS J231038.88+185519.7 and SDSS J012958.51−003539.7 with ∼ 0⁰⁰. 6 resolution and SDSS J205406.42−000514.8 with ∼ 2⁰⁰. 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 M⊙. 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 the 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 (ALMA). 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 M⊙), the far-infrared luminosity (8−1000 µm; ∼ 10¹³ L⊙) and the star formation rate (2400−2700 M⊙ yr⁻¹). Finally, an analysis of the photo-dissociation regions associated with the three high redshift quasars indicates that the interstellar medium in these sources has similar properties to local starburst galaxies.