Radio properties of Compact Steep Spectrum and GHz‐Peaked Spectrum radio sources

Orienti, M.

doi:10.1002/asna.201512257

Cited by 68 publications

(61 citation statements)

References 85 publications

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“…These sources are believed to be young AGN (e.g. O'Dea 1998;Conway 2002;Murgia et al 2002;Murgia 2003;Orienti 2016) and make up more than a quarter of the sources in our unbiased sub-sample. Of the 10 peaked-spectrum sources in the sample, sufficient spectral coverage is available to determine the observed turnover frequency of seven of them to within ∼ 1 GHz (Section 4).…”

Section: Discussionmentioning

confidence: 99%

“…Compact steep-spectrum (CSS), MPS, gigahertz peakedspectrum (GPS) and high-frequency peaked (HFP) sources are all AGN that show spectral turnovers in their synchrotron spectra, that are believed to be produced by synchrotron self-absorption. GPS, MPS and CSS sources together make up between 15 and 30 per cent of the sources in flux density limited catalogues (O'Dea 1998;Orienti 2016). The observed turnover (or peak) frequencies (νo) of the CSS, MPS, GPS and HFP sources are νo < 0.5 GHz, νo < 1 GHz, 1 < νo < 5 GHz and νo > 5 GHz (O'Dea 1998;Dallacasa et al 2000;Coppejans et al 2015), respectively.…”

Section: Introductionmentioning

confidence: 98%

“…The observed turnover (or peak) frequencies (νo) of the CSS, MPS, GPS and HFP sources are νo < 0.5 GHz, νo < 1 GHz, 1 < νo < 5 GHz and νo > 5 GHz (O'Dea 1998;Dallacasa et al 2000;Coppejans et al 2015), respectively. These sources are believed to be young (rather than confined) AGN, some of which will likely evolve into FR I and FR II radio galaxies (Begelman 1996;O'Dea 1998;Snellen et al 2000;Conway 2002; De Vries et al 2002;Murgia et al 2002;Murgia 2003;Fanti 2009;An & Baan 2012;Orienti 2016). For the nearby (z ∼ 1) CSS, MPS, GPS and HFP sources, an empirical relation exists between the rest-frame turnover frequencies (νr, where νr = νo(1 + z)) and the linear sizes of the sources (O'Dea 1998; Snellen et al 2000;Orienti & Dallacasa 2014).…”

Section: Introductionmentioning

confidence: 99%

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Radio spectra of bright compact sources at z>4.5

Coppejans

Velzen

Intema

et al. 2017

Mon. Not. R. Astron. Soc.

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High-redshift quasars are important to study galaxy and active galactic nuclei (AGN) evolution, test cosmological models, and study supermassive black hole growth. Optical searches for high-redshift sources have been very successful, but radio searches are not hampered by dust obscuration and should be more effective at finding sources at even higher redshifts. Identifying high-redshift sources based on radio data is, however, not trivial. Here we report on new multi-frequency Giant Metrewave Radio Telescope (GMRT) observations of eight z > 4.5 sources previously studied at high angular resolution with very long baseline interferometry (VLBI). Combining these observations with those from the literature, we construct broad-band radio spectra of all 30 z > 4.5 sources that have been observed with VLBI. In the sample we found flat, steep and peaked spectra in approximately equal proportions. Despite several selection effects, we conclude that the z > 4.5 VLBI (and likely also non-VLBI) sources have diverse spectra and that only about a quarter of the sources in the sample have flat spectra. Previously, the majority of high-redshift radio sources were identified based on their ultra-steep spectra (USS). Recently a new method has been proposed to identify these objects based on their megahertz-peaked spectra (MPS). Neither method would have identified more than 18 per cent of the high-redshift sources in this sample. More effective methods are necessary to reliably identify complete samples of high-redshift sources based on radio data.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Radio spectra of bright compact sources at z>4.5

Coppejans

Velzen

Intema

et al. 2017

Mon. Not. R. Astron. Soc.

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“…The compact inverted-spectrum AGN core is similar to gigahertz-peaked spectrum sources (GPSs) that exhibit a peak in their radio spectra between 1 and 5 GHz and an inverted-shape spectrum at lower frequencies (Fanti 2009). GPSs are interpreted as radio AGNs in early phases of their evolution; therefore, compact inverted-spectrum radio cores of TDRGs may be considered as an indication of recent AGN activity (Randall et al 2011;Orienti 2016). Indeed, some DDRGs are known to show a mildly inverted spectrum of the core (Machalski et al 2010).…”

Section: Radio Morphologymentioning

confidence: 99%

J1216+0709: A Radio Galaxy With Three Episodes of Agn Jet Activity

Singh

Ishwara‐Chandra

Kharb

et al. 2016

ApJ

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We report the discovery of a "triple-double radio galaxy," J1216+0709, detected in deep low-frequency Giant Metrewave Radio Telescope (GMRT) observations. J1216+0709 is only the third radio galaxy, after B0925+420 and Speca, with three pairs of lobes resulting from three different episodes of active galactic nucleus (AGN) jet activity. The 610 MHz GMRT image clearly displays an inner pair of lobes, a nearly coaxial middle pair of lobes, and a pair of outer lobes that is bent with respect to the axis of the inner pair of lobes. The total end-to-end projected sizes of the inner, middle, and outer lobes are 40″ (∼95 kpc), 1 65 (∼235 kpc), and 5 7 (∼814 kpc), respectively. Unlike the outer pair of lobes, both the inner and middle pairs of lobes exhibit asymmetries in arm lengths and flux densities, but in the opposite sense, i.e., the eastern sides are farther and also brighter than the western sides, thus, suggesting the possibility of the jet being intrinsically asymmetric rather than due to a relativistic beaming effect. The host galaxy is a bright elliptical (m r ∼ 16.56) with M SMBH ∼ 3.9 × 10 9 M e and a star formation rate of ∼ -+ 4.66 1.61 4.65 M e yr −1 . The host galaxy resides in a small group of three galaxies (m r 17.77) and is possibly going through an interaction with faint dwarf galaxies in the neighborhood, which may have triggered the recent episodes of AGN activity.

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“…The initial stage of the radio source growth is represented by compact symmetric objects (CSOs) with sub-kiloparsec-scale structures, symmetric radio morphologies, total radio emission dominated by the mini-lobes, and kinematical ages smaller than a few thousand years (review by Orienti 2016). CSOs belong to the spectral class of gigahertz-peaked spectrum (GPS) radio galaxies, characterized by a stable, convex radio spectrum peaking at GHz frequencies (see O'Dea 1998 for a review).…”

Section: Introductionmentioning

confidence: 99%

First Detection in Gamma-Rays of a Young Radio Galaxy: Fermi-Lat Observations of the Compact Symmetric Object PKS 1718−649

Migliori

Siemiginowska

Sobolewska

et al. 2016

ApJL

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We report the γ-ray detection of a young radio galaxy, PKS 1718−649, belonging to the class of compact symmetric objects (CSOs), with the Large Area Telescope (LAT) on board the Fermi satellite. The third Fermi Gamma-ray LAT catalog (3FGL) includes an unassociated γ-ray source, 3FGL J1728.0−6446, located close to PKS 1718−649. Using the latest Pass 8 calibration, we confirm that the best-fit 1σ position of the γ-ray source is compatible with the radio location of PKS 1718−649. Cross-matching of the γ-ray source position with the positions of blazar sources from several catalogs yields negative results. Thus, we conclude that PKS 1718−649 is the most likely counterpart to the unassociated LAT source. We obtain a detection test statistics TS ∼ 36 (>5σ) with a best-fit photon spectral index Γ = 2.9 ± 0.3 and a 0.1-100 GeV photon flux density F 0.1−100 GeV = (11.5 ± 0.3) × 10 −9 ph cm −2 s −1 . We argue that the linear size (∼2 pc), the kinematic age (∼100 years), and the source distance (z = 0.014) make PKS 1718−649 an ideal candidate for γ-ray detection in the framework of the model proposing that the most compact and the youngest CSOs can efficiently produce GeV radiation via inverseCompton scattering of the ambient photon fields by the radio lobe non-thermal electrons. Thus, our detection of the source in γ-rays establishes young radio galaxies as a distinct class of extragalactic high-energy emitters and yields a unique insight on the physical conditions in compact radio lobes interacting with the interstellar medium of the host galaxy.

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Radio properties of Compact Steep Spectrum and GHz‐Peaked Spectrum radio sources

Cited by 68 publications

References 85 publications

Radio spectra of bright compact sources at z>4.5

Radio spectra of bright compact sources at z>4.5

J1216+0709: A Radio Galaxy With Three Episodes of Agn Jet Activity

First Detection in Gamma-Rays of a Young Radio Galaxy: Fermi-Lat Observations of the Compact Symmetric Object PKS 1718−649

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