Blazar candidates beyond redshift 4 observed by Swift

Abstract

We have selected SDSS J222032.50+002537.5 and SDSS J142048.01+120545.9 as best blazar candidates out of a complete sample of extremely radio-loud quasars at z>4, with highly massive black holes. We observed them and a third serendipitous candidate with similar features (PMN J2134-0419) in the X-rays with the Swift/XRT telescope, to confirm their blazar nature. We observed strong and hard X-ray fluxes (i.e. ${\alpha }_X<0.6$, where $F(\nu )\propto {\nu }^{-{\alpha }_X}$ in the 0.3-10keV observed energy range, ~1-40keV rest frame) in all three cases. This allowed us to classify our candidates as real blazars, being characterized by large Lorentz factors (~13) and very small viewing angles (~3deg). All three sources have black hole masses exceeding 10^9Msun and their classification provides intriguing constraints on supermassive black hole formation and evolution models. We confirm our earlier suggestion that there are different formation epochs of extremely massive black holes hosted in jetted (z~4) and non-jetted systems (z~2.5).

8 pages, 6 figures, published on MNRAS

References in corpus (4)

• A Catalog of Quasar Properties from SDSS DR7
• An Observational Determination of the Bolometric Quasar Luminosity Function
• GROND - a 7-channel imager
• The Spectral Energy Distribution of the High-Z Blazar Q0906+693

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• The evolution of the heaviest super-massive black-holes in jetted AGNs
• BASS XXXIII: Swift-BAT blazars and their jets through cosmic time
• VLBI observations of four radio quasars at $z>4$: blazars or not?
• The central engine of the highest redshift blazar
• The Impact of the CMB on the Evolution of high-z Blazars
• A small radio galaxy at z=4.026
• Extended X-ray emission from the z=4.26 radio galaxy 4C 63.20
• Central Engine and Spectral Energy Distribution Properties of High Redshift Gamma Ray Blazars
• Superluminal Motion and Jet Parameters in the Gamma-ray-Emitting Narrow-Line Seyfert 1 Galaxy TXS 1206+549
• Radio properties of high-redshift galaxies at $z\ge 1$