Imaging the cold molecular gas in SDSS J1148 + 5251 at z = 6.4
Stefan, Irina I
Riechers, Dominik A
Monthly Notices of the Royal Astronomical Society
Oxford University Press
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Stefan, I. I., Carilli, C., Wagg, e., Walter, F., Riechers, D. A., Bertoldi, F., Green, D., et al. (2015). Imaging the cold molecular gas in SDSS J1148 + 5251 at z = 6.4. Monthly Notices of the Royal Astronomical Society, 451 1713-1718. https://doi.org/10.1093/mnras/stv1108
We present Karl G. Jansky Very Large Array (VLA) observations of the CO (J = 2 → 1) line emission towards the z = 6.419 quasar SDSS J114816.64 + 525150.3 (J1148 + 5251). The molecular gas is found to be marginally resolved with a major axis of 0.9 arcsec (consistent with previous size measurements of the CO (J = 7 → 6) emission). We observe tentative evidence for extended line emission towards the south-west on a scale of ∼1.4 arcsec, but this is only detected at 3.3σ significance and should be confirmed. The position of the molecular emission region is in excellent agreement with previous detections of low-frequency radio continuum emission as well as [C II] line and thermal dust continuum emission. These CO (J = 2 → 1) observations provide an anchor for the low-excitation part of the molecular line spectral energy distribution. We find no evidence for extended low-excitation component, neither in the spectral line energy distribution nor the image. We fit a single kinetic gas temperature model of 50 K. We revisit the gas and dynamical masses in light of this new detection of a low-order transition of CO, and confirm previous findings that there is no extended reservoir of cold molecular gas in J1148 + 5251, and that the source departs substantially from the low-z relationship between black hole mass and bulge mass. Hence, the characteristics of J1148 + 5251 at z = 6.419 are very similar to z ∼ 2 quasars, in the lack of a diffuse cold gas reservoir and kpc-size compactness of the star-forming region.
galaxies: active, galaxies: formation, galaxies: high-redshift, galaxies: individual: SDSS J114816.64 + 525150.3, cosmology: observations, radio lines: galaxies
IIS thanks the Science & Technology Facilities Council for a studentship.
External DOI: https://doi.org/10.1093/mnras/stv1108
This record's URL: https://www.repository.cam.ac.uk/handle/1810/248540