Informazioni sull’evento


Attenzione: a seguito delle disposizioni per il contenimento della diffusione del coronavirus, i seminari saranno in modalità online. Il link per il collegamento verrà reso disponibile nei giorni precedenti la data del seminario. Qui, invece, la playlist dei remote talks già messi in rete »

Astrophysics Talk

Exotic Quasars in the Early Universe

Bradford Snios (Smithsonian Astrophysical Observatory)

Tuesday 20/04/2021 @ 14:00, Sala IV piano Battiferro

Studies of high-redshift quasars provide new opportunities to investigate evolutionary properties of the Universe, and X-ray observations are uniquely adept at constraining these properties. In my talk, I report a recent analysis of Chandra X-ray observations of 15 young radio quasars at redshifts 4.5 < z < 5.0. The optical–X-ray power-law spectral index as well as the rest-frame radio-X-ray luminosities are derived for the quasar sample, and overall trends are discussed. From the multiwavelength analysis, several outliers within the sample are identified. In particular, I highlight the discovery of a heavily obscured quasar candidate in the early Universe at z=4.56. Based on the X-ray spectroscopic analysis, the source has an estimated obscuring column density in excess of 10**24 / cm**2, making it the fourth known Compton-thick quasar at z > 4.

Scarica le slides (pdf)