2019A&A...628A..56K


Query : 2019A&A...628A..56K

2019A&A...628A..56K - Astronomy and Astrophysics, volume 628A, 56-56 (2019/8-1)

Extragalactic megahertz-peaked spectrum radio sources at milliarcsecond scales.

KEIM M.A., CALLINGHAM J.R. and ROTTGERING H.J.A.

Abstract (from CDS):

Extragalactic peaked-spectrum radio sources are thought to be the progenitors of larger, radio-loud active galactic nuclei (AGN). Synchrotron self-absorption (SSA) has often been identified as the cause of their spectral peak. The identification of new megahertz-peaked spectrum sources from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey provides an opportunity to test how radio sources with spectral peaks below 1GHz fit within this evolutionary picture. We observed six peaked-spectrum sources selected from the GLEAM survey, three that have spectral characteristics which violate SSA and three that have spectral peaks below 230 MHz, with the Very Long Baseline Array at 1.55 and 4.96GHz. We present milliarcsecond resolution images of each source and constrain their morphology, linear size, luminosity, and magnetic field strength. Of the sources that are resolved by our study, the sources that violate SSA appear to be compact doubles, while the sources with peak frequencies below 230 MHz have core-jet features. We find that all of our sources are smaller than expected from SSA by factors of ≥20. We also find that component magnetic field strengths calculated from SSA are likely inaccurate, differing by factors of ≥5 from equipartition estimates. The calculated equipartition magnetic field strengths more closely resemble estimates from previously studied gigahertz-peaked spectrum sources. Exploring a model of the interaction between jets and the interstellar medium, we demonstrate that free-free absorption (FFA) can accurately describe the linear sizes and peak frequencies of our sources. Our findings support the theory that there is a fraction of peaked-spectrum sources whose spectral peaks are best modeled by FFA, implying our understanding of the early stages of radio AGN is incomplete.

Abstract Copyright: © ESO 2019

Journal keyword(s): galaxies: active - galaxies: evolution - radio continuum: galaxies

VizieR on-line data: <Available at CDS (J/A+A/628/A56): list.dat fits/*>

Status at CDS : All or part of tables of objects will not be ingested in SIMBAD.

Simbad objects: 17

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Number of rows : 17
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 PKS 0008-42 Rad 00 10 52.51972 -41 53 10.7911   22.0       ~ 65 1
2 4C -03.07 QSO 02 28 53.2112655818 -03 37 37.125617755   17.03 16.96 16.8   ~ 146 1
3 ACO 362 ClG 02 31 42.20 -04 52 53.1           ~ 37 0
4 GLEAM J023159-043352 Rad 02 31 59.745 -04 33 52.56           ~ 1 0
5 2MASS J02351685-0100512 EmG 02 35 16.810 -01 00 51.72           ~ 4 1
6 WISEA J023516.81-010051.5 MIR 02 35 16.8117 -01 00 51.595           ~ 1 0
7 QSO B0237-027 QSO 02 39 45.47226775 -02 34 40.9144020   19.5 21 19.04   ~ 114 1
8 6dFGS gJ033023.1-074053 BLL 03 30 23.1152907951 -07 40 52.555566492   19.13   18.18   ~ 3 0
9 VCS5 J0335-0709 Rad 03 35 57.0551203 -07 09 55.851893           ~ 7 0
10 3C 186 QSO 07 44 17.4723761217 +37 53 17.249506697   17.5 18.14 17.2   ~ 291 1
11 ICRF J150721.7+123629 QSO 15 07 21.7580949 +12 36 29.076399           ~ 12 1
12 4C 14.58 Rad 15 09 15.6 +14 06 14   17.5       ~ 8 1
13 ICRF J152122.5+042030 BiC 15 21 22.5436020 +04 20 30.136860   15.6 16     ~ 51 1
14 4C 03.33 AG? 15 25 48.9544 +03 08 26.177           ~ 27 1
15 NVSS J154852+132056 Rad 15 48 52.7 +13 20 56           ~ 2 2
16 QSO B1551+130 QSO 15 53 32.6979155757 +12 56 51.714849889   18.05 17.65 17.1   ~ 134 1
17 QSO B2134+0028 QSO 21 36 38.5862648232 +00 41 54.210724774   17.30 17.08 17.02   ~ 533 2

    Equat.    Gal    SGal    Ecl

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2021.07.25-15:10:44

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