2008A&A...487..885O


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.17CET20:16:45

2008A&A...487..885O - Astronomy and Astrophysics, volume 487, 885-894 (2008/9-1)

Are young radio sources in equipartition?.

ORIENTI M. and DALLACASA D.

Abstract (from CDS):

The knowledge of physical conditions in young radio sources is important for defining the framework of models describing radio source evolution. We investigate whether young radio sources are in equipartition (i.e. minimum energy) conditions by comparing the equipartition magnetic fields of 5 High Frequency Peakers (HFP) with values directly inferred from the spectral peak assumed to be produced by synchrotron self absorption. Multi-frequency VLBA observations of 5 HFPs were carried out in both the optically thick and thin part of the spectrum to determine the spectral shape and angular size of the components for which individual radio spectra were obtained. We find that the magnetic fields measured using observations agree well with those obtained by assuming equipartition, which implies that these sources are in minimum energy condition and the turnover in their spectra is due probably to SSA. In two source components, we found that the peak of the spectrum is caused by absorption of a thermal plasma instead of being due to SSA. The magnetic fields found in the various components range from 10 to 100 mG. In the presence of such high magnetic fields, electron populations with rather low γ emit in the GHz-regime. In one source, we detect low-surface brightness extended emission at low frequency located ∼30 mas (∼50 pc) from the main source. This feature may be related to either an earlier episode of radio activity or a discontinuous start of the radio activity (sputtering). By comparing our data with previous VLBA observations, we estimate the hotspot advance speed to be in the range 0.1-0.7c and kinematic ages of a few hundred years.

Abstract Copyright:

Journal keyword(s): galaxies: active - radio continuum: general - magnetic fields - radiation mechanisms: non-thermal

Simbad objects: 12

goto Full paper

goto View the reference in ADS

Number of rows : 12

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 ICRF J000319.3+212944 Sy2 00 03 19.35003510 +21 29 44.5075377   21.005 20.580 19.650   ~ 38 1
2 QSO B0002+0507 QSO 00 05 20.2154590 +05 24 10.802383   16.56 16.21 16.26   ~ 168 1
3 QSO B0108+388 Bla 01 11 37.31680 +39 06 28.1039     22 22.000   ~ 231 1
4 ICRF J042805.8+325952 QSO 04 28 05.80872626 +32 59 52.0437647       21.39   ~ 35 0
5 7C 055201.39+394824.00 QSO 05 55 30.80561150 +39 48 49.1649664     18.0 17.5   ~ 458 2
6 QSO B0646+600 QSO 06 50 31.25435513 +60 01 44.5558800   18.9 18.6 19.65   ~ 101 1
7 ICRF J092703.0+390220 Sy1 09 27 03.0139516273 +39 02 20.847968628   17.17 17.00 16.486   ~ 920 1
8 QSO B1404+286 BLL 14 07 00.3933203928 +28 27 14.695133019   16.13 15.35 10.29   ~ 657 2
9 2MASSI J1459584+333701 Sy1 14 59 58.4360595961 +33 37 01.776493680   16.89 16.70 16.5   ~ 46 0
10 ICRF J151141.2+051809 Sy1 15 11 41.26654675 +05 18 09.2597600   18.49 17.80 13.95   ~ 77 0
11 QSO B1848+283 QSO 18 50 27.5896910962 +28 25 13.154274911   17.1 17 17.16   ~ 69 1
12 QSO B1946+708 Bla 19 45 53.51992731 +70 55 48.7321708   18.726 16.70 17.199   ~ 124 2

    Equat.    Gal    SGal    Ecl

To bookmark this query, right click on this link: simbad:objects in 2008A&A...487..885O and select 'bookmark this link' or equivalent in the popup menu


2019.11.17-20:16:45

© Université de Strasbourg/CNRS

    • Contact