The first blazar observed at z > 6

被引：66
作者：
Belladitta, S. [1 ,2 ]
Moretti, A. [1 ]
Caccianiga, A. [1 ]
Spingola, C. [3 ,4 ]
Severgnini, P. [1 ]
Della Ceca, R. [1 ]
Ghisellini, G. [5 ]
Dallacasa, D. [3 ,4 ]
Sbarrato, T. [5 ,6 ]
Cicone, C. [7 ]
Cassara, L. P. [8 ]
Pedani, M. [9 ]
机构：
[1] INAF Osservatorio Astron Brera, Via Brera 28, I-20121 Milan, Italy
[2] Univ Insubria, DiSAT, Via Valleggio 11, I-22100 Como, Italy
[3] INAF Ist Radioastron, Via Gobetti 101, I-40129 Bologna, Italy
[4] Univ Bologna, Dipartimento Fis & Astron, Via Gobetti 93-2, I-40129 Bologna, Italy
[5] INAF Osservatorio Astron Brera, Sede Merate, Via E Bianchi 46, I-23807 Merate, Italy
[6] Univ Milano Bicocca, Dipartimento Fis G Occhialini, Piazza Sci 3, I-20126 Milan, Italy
[7] Univ Oslo, Inst Theoret Astrophys, POB 1029, N-0315 Oslo, Norway
[8] INAF Ist Astrofis Spaziale & Fis Cosm IASF, Via A Corti 12, I-20133 Milan, Italy
[9] INAF Fdn Galileo Galilei, Rambla Jose Ana Fernandez Perez 7, Brena Baja 38712, TF, Spain
来源：
ASTRONOMY & ASTROPHYSICS | 2020年 / 635卷
关键词：
galaxies: active; galaxies: high-redshift; galaxies: jets; quasars: individual: PSO J030947.49+271757.31; DIGITAL SKY SURVEY; X-RAY; BLACK-HOLE; LUMINOUS QUASARS; DISTANT BLAZAR; RADIO QUASAR; DISCOVERY; EVOLUTION; EMISSION; SPECTRA;
D O I：
10.1051/0004-6361/201937395
中图分类号：
P1 [天文学];
学科分类号：
0704 ;
摘要：
We present the discovery of PSO J030947.49 +271757.31, the radio brightest (23.7 mJy at 1.4 GHz) active galactic nucleus (AGN) at z > 6:0. It was selected by cross-matching the NRAO VLA Sky Survey and the Panoramic Survey Telescope and Rapid Response System PS1 databases and its high-z nature was confirmed by a dedicated spectroscopic observation at the Large Binocular Telescope. A pointed Neil Gehrels Swift Observatory XRT observation allowed us to measure a flux of 3:4 10 14 erg s 1 cm 2 in the [0.5-10] keV energy band, which also makes this object the X-ray brightest AGN ever observed at z > 6:0. Its flat radio spectrum (ff r < 0:5), very high radio loudness (R > 103), and strong X-ray emission, compared to the optical, support the hypothesis of the blazar nature of this source. Assuming that this is the only blazar at this redshift in the surveyed area of sky, we derive a space density of blazars at z 6 and with M1450A < 25:1 of 5.5 +11:2 4:6 10 3 Gpc 3. From this number, and assuming a reasonable value of the bulk velocity of the jet ( = 10), we can also infer a space density of the entire radio-loud AGN population at z 6 with the same optical /UV absolute magnitude of 1.10+2:53 0:91 Gpc 3. Larger samples of blazars will be necessary to better constrain these estimates.
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页数：7
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