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J/A+A/450/959       VLBA images of High Frequency Peakers       (Orienti+, 2006)

VLBA images of High Frequency Peakers. Orienti M., Dallacasa D., Tinti S., Stanghellini C. <Astron. Astrophys. 450, 959 (2006)> =2006A&A...450..959O
ADC_Keywords: Active gal. nuclei ; QSOs ; Radio sources Keywords: galaxies: active - galaxies: nuclei - radio continuum: galaxies - galaxies: quasar: general Abstract: We propose a morphological classification based on the parsec scale structure of fifty-one High Frequency Peakers (HFPs) from the "bright" HFP sample. VLBA images at two adjacent frequencies (chosen among 8.4, 15.3, 22.2 and 43.2GHz) have been used to investigate the morphological properties of the HFPs in the optically thin part of their spectrum. We confirm that there is quite a clear distinction between the pc-scale radio structure of galaxies and quasars: the 78% of the galaxies show a "Double/Triple" morphology, typical of Compact Symmetric Objects (CSOs), while the 87% of the quasars are characterised by Core-Jet or unresolved structure. This suggests that most HFP candidates identified with quasars are likely blazar objects in which a flaring self-absorbed component at the jet base was outshining the remainder of the source at the time of the selection based on the spectral shape. Among the sources classified as CSOs or candidates it is possible to find extremely young radio sources with ages of about 100 years or even less. Description: We present results from new multi-frequency VLBA of a sample of 51 High Frequency Peaker radio sources. Physical parameters like the total flux density, the spectral index, and the deconvolved angular sizes of major and minor axis, the position angle and the equipartition magnetic field of the sources have been estimated on the VLBA images. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 80 55 The VLBA flux density of candidates High Frequency Peaker table3.dat 72 34 The VLBA flux density of each component, for the sources with a CSO-like morphology table4.dat 72 12 The VLBA flux density of Core-Jet (CJ) source components
See also: J/A+A/363/887 : High frequency peakers. I. The bright sample (Dallacasa+, 2000) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 10 A10 --- Source Source name (J2000) (1) 14- 20 F7.5 --- z ? Redshift 23- 24 A2 --- Type [BL EF G Q] Optical type (2) 26- 30 I5 mJy S8A ?=- VLA 8.4GHz flux density 32- 36 I5 mJy S8B ?=- VLBA 8.4GHz flux density 39- 43 I5 mJy S15A ?=- VLA 15.3GHz flux density 46- 49 I4 mJy S15B ?=- VLBA 15.3GHz flux density 52- 55 I4 mJy S22A ?=- VLA 22.2GHz flux density 59- 62 I4 mJy S22B ?=- VLBA 22.2GHz flux density 64- 67 I4 mJy S43B ?=- VLBA 43.2GHz flux density 69- 72 F4.1 --- alpha ?=- Spectral index (G1) 74- 76 I3 mG Heq ?=- Equipartition magnetic field (G2) 78- 80 A3 --- Morph Morphological classification from VLBA images (3)
Note (1): The two sources J0111+3906 and J1751+0939 were not observed, since they are already plenty of information. The sources J0927+3902 and J1407+2827 have been observed only for an extremely short period of time, to verify the system performance. Note (2): Optical identification from Dallacasa et al. (2000, J/A+A/363/887), Dallacasa et al. (2002A&A...382...53D), Dallacasa et al. (2006, in preparation) (BL Lac, EmptyField, Galaxy or Quasar) Note (3): Morphological classification as follows: CJ = Core-Jet structure MR = Marginally Resolved Un = unresolved structure CSO = Compact Symmetric Objects
Byte-by-byte Description of file: table3.dat table4.dat
Bytes Format Units Label Explanations
1- 10 A10 --- Source Source name (J2000) 12- 13 A2 --- m_Source Component label 15- 17 I3 mJy S8B ? VLBA flux density at 8.4GHz 19- 21 I3 mJy S15B ? VLBA flux density at 15.3GHz 23- 26 I4 mJy S22B ? VLBA flux density at 22.2GHz 28- 31 I4 mJy S43B ? VLBA flux density at 43.2GHz 33- 36 F4.1 --- alpha ? Spectral index (G1) 38- 41 F4.2 mas thetamaj Deconvolved angular size of major axis (1) 44- 47 F4.2 mas thetamin Deconvolved angular size of minor axis (1) 49- 51 I3 deg PA ? Position angle of the major axis (1) 54- 56 I3 10-7T Heq Equipartition magnetic field (G2) 58- 62 F5.1 --- FreqMax ? Turnover frequency 64- 67 F4.1 mas LAS ? Angular distance between components 69- 71 I3 pc LLS ? Linear distance between components 72 A1 --- Note [*] *: For the sources with redshift unknown, we adopt z=1.00
Note (1): Deconvolved angular sizes of major and minor axis of the best-fitting Gaussian component and the position angle of the major axis as estimated on the most suitable images at the different frequencies, using JMFIT
Global notes: Note (G1): Spectral index between the two frequencies where VLBA images are available Note (G2): Equipartition magnetic field, we assume a spectral index of 0.7, expressed in mG
Acknowledgements: Monica Orienti, orienti(at)ira.cnr.it
(End) Patricia Vannier [CDS] 02-Feb-2006
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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