THE SUBARCSECOND RADIO STRUCTURE IN NGC-1068 .1. OBSERVATIONS AND RESULTS

Citation
Jf. Gallimore et al., THE SUBARCSECOND RADIO STRUCTURE IN NGC-1068 .1. OBSERVATIONS AND RESULTS, The Astrophysical journal, 458(1), 1996, pp. 136-148
Citations number
43
Categorie Soggetti
Astronomy & Astrophysics
Journal title
ISSN journal
0004637X
Volume
458
Issue
1
Year of publication
1996
Part
1
Pages
136 - 148
Database
ISI
SICI code
0004-637X(1996)458:1<136:TSRSIN>2.0.ZU;2-N
Abstract
We present the results of new and archival multifrequency MERLIN and V LA observations of the hybrid starburst/Seyfert galaxy NGC 1068, with emphasis on the subarcsecond radio ''triple'' and its associated synch rotron-emitting jet. These results include measurements of the radio c ontinuum spectrum and trajectory of the radio jet, the sizes and minim um energy properties of the compact features, and linear polarization at 22 GHz. Between v = 1.4 and 22 GHz the northeastern and central com ponents (NE and C) have steep spectra: a = -1.04 +/- 0.05 and -0.67 +/ - 0.04, respectively (S-nu proportional to nu(2)). The spectrum of the subarcsecond jet flattens locally at components NE and C, implying ei ther compression or reacceleration. The southern component (S) has a v ery flat spectrum, a = -0.08 +/- 0.05 between 1.4 and 22 GHz. The brig htness temperatures of the compact features making up component S (sub components S1 and S2) are low, T-b similar to 3 x 10(5) K at 5 GHz.The radio jet bends abruptly at component C from an initial P.A. similar to 12 degrees to P.A. similar to 30 degrees. Contrary to the findings of Ulvestad, Neff, & Wilson (1987), we find no evidence for a gradual, C-shaped bending of the radio jet. The minimum pressures of the compa ct features are comparable to those of the surrounding narrow-line reg ion. We report similar to 4-5 sigma detections of linear polarization in the directions of components NE and S. The polarization is detected at 22 GHz with 0''.25 resolution, but not in the more sensitive 15 GH z data with 0''.13 resolution. This result indicates that there may be substantial Faraday depolarization toward or within the subarcsecond radio structure.