A DIRECT IMAGE OF THE INNER TORUS OF NGC-1068

Citation
Jf. Gallimore et al., A DIRECT IMAGE OF THE INNER TORUS OF NGC-1068, Astrophysics and space science, 248(1-2), 1997, pp. 253-260
Citations number
18
Categorie Soggetti
Astronomy & Astrophysics
ISSN journal
0004640X
Volume
248
Issue
1-2
Year of publication
1997
Pages
253 - 260
Database
ISI
SICI code
0004-640X(1997)248:1-2<253:ADIOTI>2.0.ZU;2-6
Abstract
We present the first VLBI observations of the compact source S1 in the radio jet of NGC 1068. Roughly 1 pc in length and 0.2 pc wide, S1 res olves into clumps aligned perpendicular to the local radio jet axis. T he radio continuum emission arises from a hot (T-e similar to 10(6) K) , dense (n(e) similar to 10(6) cm(-3)) plasma, and the source of the r adio emission is either thermal free-free emission or Thomson-reflecte d synchrotron emission. The clouds comprising S1 are opaque to soft X- radiation, and we therefore propose that S1 is the inner, ionized regi on, or 'hot zone,' of the obscuring medium surrounding the active nucl eus. The covering fraction of the hot zone is small, C-f less than or equal to 10%. Since the covering fraction of the dusty, obscuring medi um is probably much larger, the obscuring disk must either flare or wa rp outside of the hot zone. That the radio jet and hot zone axes are p erpendicular also suggests that the hot zone may be considered to trac e the outermost extent of the accretion disk.