Dark bubbles around high-redshift radio-loud active galactic nucleus
Date Issued
2016
Author(s)
Abstract
At redshift larger than 3 there is a disagreement between the number of blazars (whose jet is pointing at us) and the number of expected parents (whose jet is pointing elsewhere). Now we strengthen this claim because (I) the number of blazars identified within the Sloan Digital Sky Survey (SDSS)+Faint Images of the Radio Sky at Twenty-cm (FIRST) survey footprint increased, demanding a more numerous parent population, and (II) the detected blazars have a radio flux large enough to be above the FIRST flux limit even if the jet is slightly misaligned. The foreseen number of these slightly misaligned jets, in principle detectable, is much larger than the radio-detected sources in the FIRST+SDSS survey (at redshift larger than 4). This argument is independent of the presence of an isotropic radio component, such as the hotspot or the radio lobe, and does not depend on the bulk Lorentz factor Γ. We propose a scenario that ascribes the lack of slightly misaligned sources to an overobscuration of the nucleus by a `bubble' of dust, possibly typical of the first high-redshift quasars.
Volume
461
Issue
1
Start page
L21
Issn Identifier
0035-8711
Ads BibCode
2016MNRAS.461L..21G
Rights
open.access
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