VLBA Reveals the Absence of a Compact Radio Core in the Radio-intermediate Quasar J2242+0334 at z = 5.9 - Archive ouverte HAL Access content directly
Journal Articles The Astrophysical journal letters Year : 2022

VLBA Reveals the Absence of a Compact Radio Core in the Radio-intermediate Quasar J2242+0334 at z = 5.9

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Yuanqi Liu
  • Function : Author
Ran Wang
  • Function : Author
Emmanuel Momjian
  • Function : Author
Yingkang Zhang
  • Function : Author
Tao An
  • Function : Author
Xiaolong Yang
  • Function : Author
Jeff Wagg
  • Function : Author
Eduardo Bañados
  • Function : Author

Abstract

High-resolution imaging is crucial for exploring the origin and mechanism of radio emission in quasars, especially at high redshifts. We present 1.5 GHz Very Long Baseline Array (VLBA) images of the radio continuum emission from the radio-intermediate quasar (RIQ) J2242+0334 at z = 5.9. This object was previously detected at both 1.5 GHz and 3 GHz with the Karl G. Jansky Very Large Array (VLA) as a point source. However, there is no clear detection in the VLBA images at both the full resolution of 10.7 mas × 4.5 mas (61.7 pc × 26.0 pc) and a tapered resolution of 26 mas × 21 mas (150 pc × 121 pc). This suggests that the radio emission from the quasar is diffuse on milliarcsecond scales with surface brightness fainter than the 3σ detection limit of 40.5 μJy beam-1 in the full-resolution image. The radio emission in the RIQ J2242+0334 is likely to be wind-like (i.e., diffuse) rather than in the form of collimated jets. This is different from the previous radio detections of the most luminous quasars at z ~ 6 that are usually dominated by compact, high brightness temperature radio sources. Meanwhile, compared with RIQs at low redshifts, the case of J2242+0334 suggests that not all RIQs are beamed radio-quiet quasars. This optically faint RIQ provides an important and unique example to investigate the radio activity in the less powerful active galactic nuclei at the earliest cosmic epoch.
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Dates and versions

insu-03839626 , version 1 (04-11-2022)

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Attribution - CC BY 4.0

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Yuanqi Liu, Ran Wang, Emmanuel Momjian, Yingkang Zhang, Tao An, et al.. VLBA Reveals the Absence of a Compact Radio Core in the Radio-intermediate Quasar J2242+0334 at z = 5.9. The Astrophysical journal letters, 2022, 939, ⟨10.3847/2041-8213/ac98b2⟩. ⟨insu-03839626⟩
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