Issue |
A&A
Volume 692, December 2024
|
|
---|---|---|
Article Number | A241 | |
Number of page(s) | 17 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/202451376 | |
Published online | 17 December 2024 |
Multi-wavelength properties of three new radio-powerful z ∼ 5.6 quasi-stellar objects discovered from RACS
1
INAF, Osservatorio Astronomico di Brera, via Brera 28, 20121 Milano, Italy
2
SKA Observatory, Science Operations Centre, CSIRO ARRC, 26 Dick Perry Avenue, Kensington, WA 6151, Australia
3
CSIRO Space & Astronomy, PO Box 1130 Bentley, WA 6102, Australia
4
David A. Dunlap Department of Astronomy & Astrophysics, University of Toronto, 50 St. George St., Toronto, Ontario M5S 3H4, Canada
5
Dunlap Institute for Astronomy & Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4, Canada
6
Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
7
Australian Astronomical Observatory, 105 Delhi Road, North Ryde, NSW 2113, Australia
8
Department of Physics and Astronomy, Macquarie University, NSW 2109, Australia
9
Australian Research Council Centre of Excellence for All-Sky Astrophysics in 3 Dimensions (ASTRO 3D), Canberra, Australia
10
INFN, Sezione di Milano-Bicocca, Piazza della Scienza 3, I-20126 Milano, Italy
11
INAF – Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate, Italy
12
International Centre for Radio Astronomy Research, Curtin University, 1 Turner Avenue, Bentley, WA 6102, Australia
13
Shanghai Astronomical Observatory, Chinese Academy of Sciences (CAS), 80 Nandan Road, Shanghai 200030, China
14
School of Astronomy and Space Sciences, University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China
15
Key Laboratory of Radio Astronomy and Technology, CAS, A20 Datun Road, Beijing 100101, PR China
16
Max Planck Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany
17
INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Gobetti 93/3, I-40129 Bologna, Italy
18
INAF – Istituto di Astrofisica Spaziale e Fisica Cosmica (IASF), Via A. Corti 12, 20133 Milano, Italy
⋆ Corresponding author; luca.ighina@inaf.it
Received:
4
July
2024
Accepted:
4
November
2024
We present a multi-wavelength study of three new z ∼ 5.6 quasi-stellar objects (QSOs) identified from dedicated spectroscopic observations. The three sources were selected as high-z candidates based on their radio and optical/near-infrared properties as reported in the Rapid ASKAP Continuum Survey (RACS), the Dark Energy Survey (DES), and the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) survey. These are among the most radio-bright QSOs currently known at z > 5.5, relative to their optical luminosity, having R = S5GHz/S4400Å > 100. In this work, we present their identification, and we also discuss their multi-wavelength properties (from the radio to the X-ray band) based on detections in public surveys as well as in dedicated radio and X-ray observations. The three sources present a wide range of properties in terms of relative intensity and spectral shape, highlighting the importance of multi-wavelength observations in accurately characterising these high-z objects. In particular, from our analysis we found one source at z = 5.61 that presents clear blazar properties (strong radio and X-ray emission), making it one of the most distant currently known in this class. Moreover, from the fit of the optical/near-infrared photometric measurements with an accretion disc model as well as the analysis of the CIV broad emission line in one case, we were able to estimate the mass and accretion rate of the central black holes in these systems, finding MBH ∼ 1 − 10 × 109 M⊙ accreting at a rate λEdd ∼ 0.1 − 0.4. The multi-wavelength characterisation of radio QSOs at z > 5.5, such as the ones reported here, is essential to constraining the evolution of relativistic jets and supermassive black holes hosted in this class of objects.
Key words: galaxies: active / galaxies: high-redshift / galaxies: jets / quasars: general / quasars: supermassive black holes
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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