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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



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ID: 448180.0, MPI für Astronomie / Publikationen_mpia
High-redshift obscured quasars: radio emission at sub-kiloparsec scales
Authors:Klöckner, H. R.; Martínez-Sansigre, A.; Rawlings, S.; Garrett, M. A.
Language:English
Date of Publication (YYYY-MM-DD):2009
Title of Journal:Monthly Notices of the Royal Astronomical Society
Journal Abbrev.:MNRAS
Volume:398
Start Page:176
End Page:188
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:The radio properties of 11 obscured `radio-intermediate' quasars at redshifts z >~ 2 have been investigated using the European Very-Long-Baseline-Interferometry Network (EVN) at 1.66 GHz. A sensitivity of ~25μJy per 17 × 14mas2beam was achieved, and in seven out of 11 sources unresolved radio emission was securely detected. The detected radio emission of each source accounts for ~30-100 per cent of the total source flux density. The physical extent of this emission is <~150pc, and the derived properties indicate that this emission originates from an active galactic nucleus (AGN). The missing flux density is difficult to account for by star formation alone, so radio components associated with jets of physical size >~150pcand <~40 kpc are likely to be present in most of the sources. Amongst the observed sample steep, flat, gigahertz-peaked and compact-steep spectrum sources are all present. Hence, as well as extended and compact jets, examples of beamed jets are also inferred, suggesting that in these sources, the obscuration must be due to dust in the host galaxy, rather than the torus invoked by the unified schemes. Comparing the total to core (<~150pc) radio luminosities of this sample with different types of AGN suggests that this sample of z >~ 2 radio-intermediate obscured quasars shows radio properties that are more similar to those of the high-radio-luminosity end of the low-redshift radio-quiet quasar population than those of Fanaroff-Riley type I (FRI) radio galaxies. This conclusion may reflect intrinsic differences, but could be strongly influenced by the increasing effect of inverse-Compton cooling of extended radio jets at high redshift.
Free Keywords:techniques: interferometric; galaxies: active; galaxies: nuclei; quasars: general; radio continuum: galaxies
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2009MNRAS.398..176K [ID No:1]
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