What are the gigahertz peaked-spectrum radio sources?

O’Dea, C. P.; Baum, Stefi A.; Stanghellini, C.

doi:10.1086/170562

Cited by 255 publications

(295 citation statements)

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“…There is a third classification called FR-c galaxies. These galaxies have very compact radio continuum emission.Their radio morphologies suggest that they are compact versions of the classical FR-II's, although why they are so small has not yet been established: they may be either young FR-IIs or FR-IIs trapped in a dense environment (Fanti et al 1990;O'Dea et al 1991;Fanti & Fanti 1994). In the present sample, 69.2% are FR-I type galaxies, 19.2% are FR-II type galaxies, and 11.5% are FR-c type galaxies.…”

Section: Fanaroff and Riley Classificationmentioning

confidence: 99%

TANGO I: Interstellar medium in nearby radio galaxies

Flaquer¹,

Léon²,

Combes³

et al. 2010

A&A

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Context. Powerful radio-AGN are hosted by massive elliptical galaxies that are usually very poor in molecular gas. Nevertheless, gas is needed at their very center to feed the nuclear activity. Aims. We study the molecular gas properties (i.e., mass, kinematics, distribution, origin) of these objects, and compare them with results for other known samples. Methods. At the IRAM-30m telescope, we performed a survey of the CO(1-0) and CO(2-1) emission from the most powerful radio galaxies of the Local Universe, selected only on the basis of their radio continuum fluxes. Results. The main result of our survey is that the molecular gas content of these galaxies is very low compared to spiral or FIR-selected galaxies. The median value of the molecular gas mass, including detections and upper limits, is 2.2 × 10 8 M . When separated into FR-I and FR-II types, a difference in their H 2 masses is found. The median value of FR-I galaxies is about 1.9 × 10 8 M and higher for FR-II galaxies, at about 4.5 × 10 8 M . Which is probably entirely because of a Malmquist bias. Our results contrast with those of previous surveys, whose targets were mainly selected by means of their FIR emission, implying that we measure higher observed masses of molecular gas. Moreover, the shape of CO spectra suggest that a central molecular gas disk exists in 30% of these radio galaxies, a lower rate than in other active galaxy samples. Conclusions. We find a low level of molecular gas in our sample of radio-selected AGNs, indicating that galaxies do not need much molecular gas to host an AGN. The presence of a molecular gas disk in some galaxies and the wide range of molecular gas masses may be indicative of different origins for the gas, which we can not exclude at present (e.g., minor/major mergers, stellar mass loss, or accretion).

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Section: Fanaroff and Riley Classificationmentioning

confidence: 99%

TANGO I: Interstellar medium in nearby radio galaxies

Flaquer¹,

Léon²,

Combes³

et al. 2010

A&A

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“…It is plausible that densities in GPS sources are large enough that free-free absorption may play a role (O'Dea et al 1991;Stawarz et al 2008). The emission measure for free-free absorption at 5 GHz is (see, e.g., Osterbrock 1977):…”

Section: X-ray Emission Entirely Associated With Radio-emitting Regions?mentioning

confidence: 99%

The X-ray view of giga-hertz peaked spectrum radio galaxies

Tengstrand

Guainazzi

Siemiginowska

et al. 2009

A&A

100

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Context. This paper presents the X-ray properties of a flux-and volume-limited complete sample of 16 giga-hertz peaked spectrum (GPS) galaxies. Aims. This study addresses three basic questions in our understanding of the nature and evolution of GPS sources: a) What is the physical origin of the X-ray emission in GPS galaxies? b) Which physical system is associated with the X-ray obscuration? c) What is the "endpoint" of the evolution of compact radio sources? Methods. We discuss in this paper the results of the X-ray spectral analysis, and compare the X-ray properties of the sample sources with radio observables. Results. We obtain a 100% (94%) detection fraction in the 0.5-2 keV (0.5-10 keV) energy band. GPS galaxy X-ray spectra are typically highly obscured ( N GPS H = 3 × 10 22 cm −2 ; σ N H 0.5 dex). The X-ray column density is larger than the HI column density measured in the radio by a factor 10 to 100. GPS galaxies lie well on the extrapolation to high radio powers of the correlation between radio and X-ray luminosity known in low-luminosity FR I radio galaxies. On the other hand, GPS galaxies exhibit a comparable X-ray luminosity to FR II radio galaxies, notwithstanding their much larger radio luminosity. Conclusions. The X-ray to radio luminosity ratio distribution in our sample is consistent with the bulk of the high-energy emission being produced by the accretion disk, as well as with dynamical models of GPS evolution where X-rays are produced by Compton upscattering of ambient photons. Further support to the former scenario comes from the location of GPS galaxies in the X-ray to O[iii] luminosity ratio versus N H plane. We propose that GPS galaxies are young radio sources, which would reach their full maturity as classical FR II radio galaxies. However, column densities ∼ > 10 22 cm −2 could lead to a significant underestimate of dynamical age determinations based on the hotspot recession velocity measurements.

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“…O'Dea & Baum (1997) and Snellen et al (2000) suggested that the observed anti-correlation between νT and the linear size of GPS sources could be explained by SSA. However, Bicknell et al (1997) proposed an alternative model with FFA occurring in an ionized gas surrounding the radio emitting regions.…”

Section: Introductionmentioning

confidence: 99%

Multifrequency VLBA polarimetry of the high-redshift GPS quasar OQ172

Liu

Jiang

et al. 2017

Monthly Notices of the Royal Astronomical Society

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Multi-frequency Very Long Baseline Array (VLBA) polarimetry observation of the GHz-Peaked Spectrum (GPS) quasar OQ172 (J1445+0958) has been performed at 1.6, 2.2, 4.8, 8.3 and 15.3 GHz in 2005. Core-jet structures are detected in all bands with the jet strongly bent at about 3 mas from the core. The radio emission of the source is polarised at all five bands. We study the Faraday Rotation in the core and jet components at all five bands, and find good linear fits of Faraday Rotation in the core and jet components at 4.8 and 8.3 GHz. At these two frequencies, the Rotation Measure (RM) is ∼ 2000 rad m −2 in the core and ∼ 700 rad m −2 in the inner jet components and continues to decrease at the outer jet parts. We find that the depolarisation at 4.8 and 8.3 GHz might be caused by the internal medium in the source. We investigate consistency of the turnover spectra of VLBI components with the Synchrotron SelfAbsorption (SSA) and Free-Free Absorption (FFA) models. Although these two models can not be easily distinguished due to the lack of low-frequency data, the physical parameters can be constrained for each model. We find that the large width of the [OIII] 5007 line is likely caused by a jet interaction with a Narrow Line Region (NLR) medium. The jet bending, significant RM variations, Faraday depolarisation, spectral turnover, and broad line width of [OIII] 5007 could be closely related, likely caused by the same nucleus medium, presumably NLR.

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What are the gigahertz peaked-spectrum radio sources?

Cited by 255 publications

References 0 publications

TANGO I: Interstellar medium in nearby radio galaxies

TANGO I: Interstellar medium in nearby radio galaxies

The X-ray view of giga-hertz peaked spectrum radio galaxies

Multifrequency VLBA polarimetry of the high-redshift GPS quasar OQ172

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