Radio Quasars in the Cosmic Dawn: A Spectroscopic Sample from the DESI Survey

@article{gloudemans2026radio,
  title = {{Radio Quasars in the Cosmic Dawn: A Spectroscopic Sample from the DESI Survey}},
  author = {Anniek J. Gloudemans and Jinyi Yang and David M. Alexander and Arjun Dey and Xiaohui Fan and Victoria A. Fawcett and Martin J. Hardcastle and Stephanie Juneau and George K. Miley and Leah K. Morabito and Adam D. Myers and Swayamtrupta Panda and Huub J. A. Röttgering and Timothy Shimwell and Daniel J. B. Smith and Feige Wang and J. Aguilar and S. Ahlen and D. Bianchi and D. Brooks and T. Claybaugh and A. Cuceu and A. de la Macorra and P. Doel and S. Ferraro and J. E. Forero-Romero and E. Gaztañaga and S. Gontcho A Gontcho and G. Gutierrez and C. Hahn and M. Ishak and R. Joyce and R. Kehoe and D. Kirkby and T. Kisner and A. Kremin and M. Landriau and L. Le Guillou and M. E. Levi and M. Manera and A. Meisner and R. Miquel and J. Moustakas and S. Nadathur and W. J. Percival and F. Prada and I. Pérez-Ràfols and A. Robertson and G. Rossi and E. Sanchez and E. F. Schlafly and D. Schlegel and J. Silber and D. Sprayberry and G. Tarlé and B. A. Weaver and R. Zhou and H. Zou},
  journal = {The Astrophysical Journal},
  year = {2026},
  month = nov,
  doi = {10.3847/1538-4357/aeaade},
  url = {https://iopscience.iop.org/article/10.3847/1538-4357/aeaade},
  note = {CC BY 4.0},
}

TY  - JOUR
TI  - Radio Quasars in the Cosmic Dawn: A Spectroscopic Sample from the DESI Survey
AU  - Anniek J. Gloudemans
AU  - Jinyi Yang
AU  - David M. Alexander
AU  - Arjun Dey
AU  - Xiaohui Fan
AU  - Victoria A. Fawcett
AU  - Martin J. Hardcastle
AU  - Stephanie Juneau
AU  - George K. Miley
AU  - Leah K. Morabito
AU  - Adam D. Myers
AU  - Swayamtrupta Panda
AU  - Huub J. A. Röttgering
AU  - Timothy Shimwell
AU  - Daniel J. B. Smith
AU  - Feige Wang
AU  - J. Aguilar
AU  - S. Ahlen
AU  - D. Bianchi
AU  - D. Brooks
AU  - T. Claybaugh
AU  - A. Cuceu
AU  - A. de la Macorra
AU  - P. Doel
AU  - S. Ferraro
AU  - J. E. Forero-Romero
AU  - E. Gaztañaga
AU  - S. Gontcho A Gontcho
AU  - G. Gutierrez
AU  - C. Hahn
AU  - M. Ishak
AU  - R. Joyce
AU  - R. Kehoe
AU  - D. Kirkby
AU  - T. Kisner
AU  - A. Kremin
AU  - M. Landriau
AU  - L. Le Guillou
AU  - M. E. Levi
AU  - M. Manera
AU  - A. Meisner
AU  - R. Miquel
AU  - J. Moustakas
AU  - S. Nadathur
AU  - W. J. Percival
AU  - F. Prada
AU  - I. Pérez-Ràfols
AU  - A. Robertson
AU  - G. Rossi
AU  - E. Sanchez
AU  - E. F. Schlafly
AU  - D. Schlegel
AU  - J. Silber
AU  - D. Sprayberry
AU  - G. Tarlé
AU  - B. A. Weaver
AU  - R. Zhou
AU  - H. Zou
PY  - 2026
DA  - 2026/11/05
JO  - The Astrophysical Journal
DO  - 10.3847/1538-4357/aeaade
UR  - https://iopscience.iop.org/article/10.3847/1538-4357/aeaade
AB  - We present the largest statistical spectroscopic sample of radio quasars at 4.7 ≤ z ≤ 6.7 to date. These have been selected from a dedicated Dark Energy Spectroscopic Instrument target program and provide a robust sample to study the influence of radio jets on early quasar evolution. Using low-frequency radio data from the LOFAR Two Metre Sky Survey Data Release 3 at 144 MHz, we identify 83 high- z radio quasars, 26 of which are classified as radio-loud (5%–15% of 646 confirmed high- z quasars, defined as R = F 5GHz / F 4400Å > 10). With radio luminosities of ∼10 ²⁵⁻²⁸ W Hz ⁻¹ , the radio emission in all 83 quasars is expected to be jet dominated rather than powered by star formation. Analysis of their rest-frame ultraviolet spectra reveals broadly similar composite spectral properties and C iv velocity shifts compared to radio-nondetected quasars. The radio-detected and radio-loud quasars exhibit slightly smaller Ly α and C iv equivalent widths on average; however, we find no significant evidence (∼1.3 σ ) for a higher fraction of weak-line quasars (∼10% ± 4% versus ∼4% ± 1% for radio-nondetected quasars). We further find that the broad absorption line (BAL) quasars are predominantly radio-quiet, and no correlation is observed between absorption index and radio-loudness, suggesting that radio emission is not produced by the BAL outflows themselves and is a physically distinct phenomenon. Our results demonstrate that powerful radio jets were already well established by z ∼ 5.
SN  - 1538-4357
SN  - 0004-637X
ER  -