The [CII] and FIR properties of z > 6 radio-loud quasars

¹ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
e-mail: khusanova@mpia.de
² European Southern Observatory, Alonso de Cordova 3107, Vitacura, Region Metropolitana, Chile
³ National Radio Astronomy Observatory, PO Box O, Socorro, NM 87801, USA
⁴ INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Gobetti 93/3, 40129 Bologna, Italy
⁵ Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
⁶ Gemini Observatory, NSF’s NOIRLab, 670 N A’ohoku Place, Hilo, Hawai’i 96720, USA
⁷ Steward Observatory, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721, USA

Received: 28 March 2022
Accepted: 26 April 2022

Abstract

There are only five radio-loud quasars currently known within 1 Gyr from the Big Bang (z > 6) and the properties of their host galaxies have not been explored in detail. We present a NOrthern Extended Millimeter Array (NOEMA) survey of [CII] (158 μm) and underlying continuum emission of four z > 6 radio-loud quasars, revealing their diverse properties. J0309+2717 (z = 6.10) has a bright [CII] line and underlying continuum, implying that the host galaxy is a starburst with a star-formation rate SFR = 340–1200 M_⊙ yr⁻¹. J1429+5447 (z = 6.18) has a SFR = 520 − 870 M_⊙ yr⁻¹ and its [CII] profile is consistent with two Gaussians, which could be interpreted as a galaxy merger. J1427+3312 (z = 6.12) has a moderate SFR = 30–90 M_⊙ yr⁻¹. Notably, this is a broad absorption line quasar and we searched for the presence of high-velocity outflows in the host galaxy. Although the NOEMA data tentatively reveal a broad component of the [CII] line as wide as ∼1400 km s⁻¹, the sensitivity of our current data are not sufficient to confirm it. Finally, P172+18 (z = 6.82) is undetected in both [CII] and the continuum, implying a SFR < 22–40 M_⊙ yr⁻¹. The broad range of SFRs is similar to what is observed in radio-quiet quasars at similar redshifts. If radio jets do not significantly contribute to both [CII] and IR luminosities, this suggests there is no feedback from the jet on the star formation in the host galaxy.