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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…
The metallicity and dust content of a redshift 5 gamma-ray burst host galaxy
M. Sparre, O. E. Hartoog, T. Krühler +26
Observations of the afterglows of long gamma-ray bursts (GRBs) allow the study of star-forming galaxies across most of cosmic history. Here we present observations of GRB 111008A f…
Molecular Hydrogen in the Damped Lyman-alpha System towards GRB 120815A at z=2.36
T. Krühler, C. Ledoux, J. P. U. Fynbo +32
We present the discovery of molecular hydrogen (H_2), including the presence of vibrationally-excited H_2^* in the optical spectrum of the afterglow of GRB 120815A at z=2.36 obtain…
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…