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NuSTAR detection of the blazar B2 1023+25 at redshift 5.3
T. Sbarrato, G. Tagliaferri, G. Ghisellini +19
B2 1023+25 is an extremely radio-loud quasar at z=5.3 which was first identified as a likely high-redshift blazar candidate in the SDSS+FIRST quasar catalog. Here we use the Nuclea…
Blazar candidates beyond redshift 4 observed with GROND
T. Sbarrato, G. Ghisellini, M. Nardini +4
The search for extremely massive high redshift blazars is essential to put strong constraints on the supermassive black holes formation theories. Up to now, the few blazars known t…
High redshift Fermi blazars observed by GROND and Swift
G. Ghisellini, M. Nardini, G. Tagliaferri +7
We observed 5 gamma-ray loud blazars at redshift greater than 2 with the X-Ray Telescope (XRT) and the UltraViolet and Optical Telescope (UVOT) onboard the Swift satellite, and the…
SDSS J102623.61+254259.5: the second most distant blazar at z=5.3
T. Sbarrato, G. Ghisellini, M. Nardini +7
The radio-loud quasar SDSS J102623.61+254259.5, at a redshift z=5.3, is one of the most distant radio-loud objects. Since its radio flux exceeds 100 mJy at a few GHz, it is also on…
The long gamma-ray burst rate and the correlation with host galaxy properties
J. Elliott, J. Greiner, S. Khochfar +3
To answer questions on the start and duration of the epoch of reionisation, periods of galaxy mergers and properties of other cosmological encounters, the cosmic star formation his…
Super-solar Metal Abundances in Two Galaxies at z ~ 3.57 revealed by the GRB 090323 Afterglow Spectrum
S. Savaglio, A. Rau, J. Greiner +12
We report on the surprisingly high metallicity measured in two absorption systems at high redshift, detected in the Very Large Telescope spectrum of the afterglow of the gamma-ray…