Milli-arcsecond imaging of the radio emission from the quasar with the most massive black hole at reionization

Abstract

We report Very Long Baseline Array (VLBA) observations of the 1.5 GHz radio continuum emission of the {\it z=6.326} quasar SDSS J010013.02+280225.8 (hereafter J0100+2802). J0100+2802 is, by far the most optically luminous, and radio-quiet quasar with the most massive black hole known at z>6. The VLBA observations have a synthesized beam size of 12.10 mas $\times$5.36 mas (FWHM), and detected the radio continuum emission from this object with a peak surface brightness of 64.6+/-9.0 micro-Jy/beam and a total flux density of 88+/-19 micro-Jy. The position of the radio peak is consistent with that from SDSS in the optical and Chandra in the X-ray. The radio source is marginally resolved by the VLBA observations. A 2-D Gaussian fit to the image constrains the source size to $\rm (7.1+/-3.5) mas x (3.1+/-1.7) mas. This corresponds to a physical scale of (40+/-20) pc x (18+/-10) pc. We estimate the intrinsic brightness temperature of the VLBA source to be T_{B}=(1.6 +/- 1.2) x 10^{7} K. This is significantly higher than the maximum value in normal star forming galaxies, indicating an AGN origin for the radio continuum emission. However, it is also significantly lower than the brightness temperatures found in highest redshift radio-loud quasars. J0100+2802 provides a unique example to study the radio activity in optically luminous and radio quiet active galactic nuclei in the early universe. Further observations at multiple radio frequencies will accurately measure the spectral index and address the dominant radiation mechanism of the radio emission.

11 pages, 2 figures, accepted for publication in ApJLetter

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Cited by in corpus (9)

• Spatially Resolved Interstellar Medium and Highly-Excited Dense Molecular Gas in the Most Luminous Quasar at z=6.327
• Constraining the quasar radio-loud fraction at $z\sim 6$ with deep radio observations
• Radio-loud Quasars above Redshift 4: VLBI Imaging of an Extended Sample
• VLBI observations of VIK J2318-3113, a quasar at z = 6.44
• XMM-Newton observation of the ultraluminous quasar SDSS J010013.02+280225.8 at redshift 6.326
• Unveiling the weak radio quasar population at z $\ge$ 4
• Exploring the radio spectral energy distribution of the ultraluminous radio-quiet quasar SDSS J0100+2802 at redshift 6.3
• High-resolution Imaging of Two Radio Quasars at the End of the Reionization Epoch
• Milliarcsecond-scale radio structure of the most distant BL Lac object candidate at redshift 6.57