2013/09/12 by T. Sbarrato, G. Tagliaferri, G. Ghisellini +26 · 1 citation
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Blazar #Galaxy #Gamma ray #Gamma-ray bursts and supernovae #Physics #Red shift #Redshift #astro-ph.CO #astro-ph.HE
paper · pdf · doi:10.1088/0004-637x/777/2/147
10 pages, 3 figures, 3 tables. Accepted for publication in ApJ
arxiv created 2013/09/12 · openalex publication_date 2013/10/23 · arxiv updated 2015/06/17 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
B2 1023+25 is an extremely radio-loud quasar at z = 5.3 that was first identified as a likely high-redshift blazar candidate in the SDSS+FIRST quasar catalog. Here, we use the Nuclear Spectroscopic Telescope Array ( NuSTAR ) to investigate its non-thermal jet emission, whose high-energy component we detected in the hard X-ray energy band. The X-ray flux is (5–10 keV) and the photon spectral index is Γ X ≃ 1.3–1.6. Modeling the full spectral energy distribution, we find that the jet is oriented close to the line of sight, with a viewing angle of ∼3°, and has significant Doppler boosting, with a large bulk Lorentz factor ∼13, which confirms the identification of B2 1023+25 as a blazar. B2 1023+25 is the first object at redshift larger than 5 detected by NuSTAR , demonstrating the ability of NuSTAR to investigate the early X-ray universe and to study extremely active supermassive black holes located at very high redshift.