Further evidence for synchrotron self‐absorption from the CORALZ sample of young radio‐loud AGN

Vries, Nathan de; Snellen, I. A. G.; Schilizzi, R. T.; Mack, K.‐H.

doi:10.1002/asna.200811159

Cited by 12 publications

(10 citation statements)

References 19 publications

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“…Analytical models with the radio emission from the compact radio sources propagating through their host galaxies provide a reasonable path for compact radio sources evolving into CSS and large-scale radio sources (e.g., Begelman 1999;Snellen et al 2000;Maciel & Alexander 2014), which is in agreement with current observations (e.g., An & Baan 2012). The global relationship between radio spectral turnover frequency and the source linear size could be reproduced under the SSA assumption (e.g., Snellen et al 2000;de Vries et al 2009;Jeyakumar 2016). In addition, the magnetic field strength calculated from the turnover, assuming it is produced by SSA for young radio sources, was found to be consistent with the magnetic field calculated under the assumption that the radio emission is in a near equipartition of energy between the radiating particles and the magnetic field (e.g., O'Dea 1998; Orienti & Dallacasa 2008).…”

Section: Introductionsupporting

confidence: 81%

The radio spectral turnover of radio-loud quasars at $z>5$

Shao,

Wagg,

Wang

et al. 2021

Preprint

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We present Karl G. Jansky Very Large Array (VLA) S-(2-4 GHz), C-(4-8 GHz), and X-band (8-12 GHz) continuum observations toward seven radio-loud quasars at z > 5. This sample has previously been found to exhibit spectral peaks at observed-frame frequencies above ∼1 GHz. We also present upgraded Giant Metrewave Radio Telescope (uGMRT) band-2 (200 MHz), band-3 (400 MHz), and band-4 (650 MHz) radio continuum observations toward eight radio-loud quasars at z > 5, selected from our previous GMRT survey, in order to sample their low-frequency synchrotron emission. Combined with archival radio continuum observations, all ten targets show evidence for spectral turnover. The turnover frequencies are ∼1-50 GHz in the rest frame, making these targets gigahertzpeaked-spectrum (GPS) or high-frequency-peaker (HFP) candidates. For the nine well-constrained targets with observations on both sides of the spectral turnover, we fit the entire radio spectrum with absorption models associated with synchrotron self-absorption and free-free absorption (FFA). Our results show that FFA in an external inhomogeneous medium can accurately describe the observed spectra for all nine targets, which may indicate an FFA origin for the radio spectral turnover in our sample. As for the complex spectrum of J114657.79+403708.6 at z = 5.00 with two spectral peaks, it may be caused by multiple components (i.e., core-jet) and FFA by the high-density medium in the nuclear region. However, we cannot rule out the spectral turnover origin of variability. Based on our radio spectral modeling, we calculate the radio loudness R 2500 Å for our sample, which ranges from 12 +1 −1 to 674 +61 −51 .

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Section: Introductionsupporting

confidence: 81%

The radio spectral turnover of radio-loud quasars at $z>5$

Shao,

Wagg,

Wang

et al. 2021

Preprint

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“…Since SSA (by default in these objects) appears to be enough, I think it is unnecessary to add a generalized second absorption mechanism (see also de Vries et al 2009). …”

Section: (Top)mentioning

confidence: 99%

Radio properties of CSSs and GPSs

Fanti¹

2009

Astron Nachr

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“…They are morphologically similar to classical double radio sources, but with size scales of <1 kpc (Phillips & Mutel 1982;Wilkinson et al 1994). The radio emission typically peaks near frequencies of a few GHz, which can be explained in most CSOs by synchrotron self-absorption in the galaxies (de Vries et al 2009a(de Vries et al , 2009b. Kinematic ages of the radio jets show that they are extremely young, with ages of 4000 yr (Owsianik & Conway 1998;Gugliucci et al 2005).…”

Section: Introductionmentioning

confidence: 99%

SPITZERMID-INFRARED SPECTROSCOPY OF COMPACT SYMMETRIC OBJECTS: WHAT POWERS RADIO-LOUD ACTIVE GALACTIC NUCLEI?

Willett

Stocke

Darling

et al. 2010

ApJ

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We present low-and high-resolution mid-infrared (mid-IR) spectra and photometry for eight compact symmetric objects (CSOs) taken with the Infrared Spectrograph on the Spitzer Space Telescope. The hosts of these young, powerful radio galaxies show significant diversity in their mid-IR spectra. This includes multiple atomic fine-structure lines, H 2 gas, polycyclic aromatic hydrocarbon (PAH) emission, warm dust from T = 50 to 150 K, and silicate features in both emission and absorption. There is no evidence in the mid-IR of a single template for CSO hosts, but 5/8 galaxies show similar moderate levels of star formation (<10 M yr −1 from PAH emission) and silicate dust in a clumpy torus. The total amount of extinction ranges from A V ∼ 10 to 30, and the high-ionization [Ne v] 14.3 and 24.3 μm transitions are not detected for any galaxy in the sample. Almost all CSOs show contributions both from star formation and active galactic nuclei (AGNs), suggesting that they occupy a continuum between pure starbursts and AGNs. This is consistent with the hypothesis that radio galaxies are created following a galactic merger; the timing of the radio activity onset means that contributions to the IR luminosity from both merger-induced star formation and the central AGN are likely. Bondi accretion is capable of powering the radio jets for almost all CSOs in the sample; the lack of [Ne v] emission suggests an advection-dominated accretion flow mode as a possible candidate. Merging black holes (BHs) with M BH > 10 8 M likely exist in all of the CSOs in the sample; however, there is no direct evidence from these data that BH spin energy is being tapped as an alternative mode for powering the radio jets.

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Further evidence for synchrotron self‐absorption from the CORALZ sample of young radio‐loud AGN

Cited by 12 publications

References 19 publications

The radio spectral turnover of radio-loud quasars at $z>5$

The radio spectral turnover of radio-loud quasars at $z>5$

Radio properties of CSSs and GPSs

SPITZERMID-INFRARED SPECTROSCOPY OF COMPACT SYMMETRIC OBJECTS: WHAT POWERS RADIO-LOUD ACTIVE GALACTIC NUCLEI?

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