Query : 2022A&A...668A.186S

2022A&A...668A.186S - Astronomy and Astrophysics, volume 668A, 186 (2022/12-1)

Extragalactic peaked-spectrum radio sources at low frequencies are young radio galaxies.


Abstract (from CDS):

We present a sample of 373 peaked-spectrum (PS) sources with spectral peaks around 150 MHz, selected using a subset of the two LOw Frequency ARray (LOFAR) all-sky surveys, the LOFAR Two Meter Sky Survey and the LOFAR LBA Sky Survey. These LOFAR surveys are the most sensitive low-frequency widefield surveys to date, allowing us to select low-luminosity peaked-spectrum sources. Our sample increases the number of known PS sources in our survey area by a factor 50. The 5 GHz luminosity distribution of our PS sample shows we sample the lowest luminosity PS sources to date by nearly an order of magnitude. Since high-frequency gigahertz-peaked spectrum sources and compact steep-spectrum sources are hypothesised to be the precursors to large radio galaxies, we investigate whether this is also the case for our sample of low-frequency PS sources. Using optical line emission criteria, we find that our PS sources are predominately high-excitation radio galaxies instead of low-excitation radio galaxies, corresponding to a quickly evolving population. We compute the radio source counts of our PS sample, and find they are scaled down by a factor of ≈40 compared to a general sample of radio-loud active galactic nuclei (AGN). This implies that the lifetimes of PS sources are 40 times shorter than large-scale radio galaxies if their luminosity functions are identical. To investigate this, we compute the first radio luminosity function for a homogeneously selected PS sample. We find that for 144 MHz luminosities ≳1025 W Hz–1, the PS luminosity function has the same shape as an unresolved radio-loud AGN population, but shifted down by a factor of ≈-pagination10. We interpret this as strong evidence that these high-luminosity PS sources evolve into large-scale radio-loud AGN. For local low-luminosity PS sources, there is a surplus of PS sources, which we hypothesise to be the addition of frustrated PS sources that do not evolve into large-scale AGN.

Abstract Copyright: © The Authors 2022

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

VizieR on-line data: <Available at CDS (J/A+A/668/A186): pscat.dat>

Status at CDS : Tables of objects will be appraised for possible ingestion in SIMBAD.

Simbad objects: 2

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Number of rows : 2
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 5C 2.183 QSO 11 10 36.32410039 +48 17 52.4497560   21.74 20.79     ~ 64 1
2 NGC 3894 SyG 11 48 50.35817663 +59 24 56.3822416   12.9   11.57   ~ 234 1

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