ChandraandXMM‐NewtonObservations of a Sample of Low‐Redshift FR I and FR II Radio Galaxy Nuclei

Evans, D. A.; Worrall, D. M.; Hardcastle, M. J.; Kraft, Ralph; Birkinshaw, Mark

doi:10.1086/500658

Cited by 187 publications

(278 citation statements)

References 69 publications

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“…Such a value is much larger than column densities measured in a control sample of FR I radio galaxies, but still less than column densities covering accretion-related X-ray spectral components in FR II radio galaxies (Balmaverde et al 2006;Belsole et al 2006;Evans et al 2006). -The X-ray column density measured in almost all GPS galaxies is larger than the HI column density measured in the radio by a factor 10 to 100.…”

Section: Discussionmentioning

confidence: 61%

“…Interestingly, the fraction of Compton-thick AGN in the GPS sample (0.12 ± 0.09, if PKS1607+26 is considered) is comparable to fractions observed in radio-quiet AGN (Heckman et al 2005). Conversely, only one Compton-thick AGN has been detected in large-scale radio galaxies (Erlund et al 2008), although FR II exhibit typically spectral components with very large obscuration (Belsole et al 2006;Evans et al 2006). …”

Section: The X-ray Obscuring Environmentmentioning

confidence: 66%

“…The control sample has been built from results recently published in the literature. It is based on observations of z < 1 radio galaxies taken by ASCA (Sambruna et al 1999), BeppoSAX , XMM-Newton and Chandra (FR I: Donato et al 2004;Evans et al 2006;Balmaverde et al 2006, FR II: Belsole et al 2006Evans et al 2006;Hardcastle et al 2006). Only one measurement per source has been retained in the control sample, based on the latest published result.…”

Section: Comparison With Control Samples Of "Normal" Radio Galaxiesmentioning

confidence: 99%

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

Tengstrand

Guainazzi

Siemiginowska

et al. 2009

A&A

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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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Section: Discussionmentioning

confidence: 61%

Section: The X-ray Obscuring Environmentmentioning

confidence: 66%

Section: Comparison With Control Samples Of "Normal" Radio Galaxiesmentioning

confidence: 99%

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

Tengstrand

Guainazzi

Siemiginowska

et al. 2009

A&A

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100

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“…In the past decade it has been demonstrated that a panchromatic, X-ray to radio, observational approach is key to develop a consensus on galaxy formation and evolution (e.g., Dickinson et al 2003;Scoville et al 2007;Driver et al 2009Driver et al , 2011Koekemoer et al 2011;Grogin et al 2011). In this context, the radio regime offers an indispensable window toward star formation and supermassive black hole properties of galaxies as radio A&A 602, A1 (2017) continuum emission i) provides a dust-unbiased star formation tracer at high angular resolution (e.g., Condon 1992;Haarsma et al 2000;Seymour et al 2008;Smolčić et al 2009b;Karim et al 2011); and ii) directly probes those active galactic nuclei (AGN) that are hosted by the most massive quiescent galaxies and deemed crucial for massive galaxy formation (e.g., Croton et al 2006;Bower et al 2006;Best et al 2006;Evans et al 2006;Hardcastle et al 2007;Smolčić et al 2009aSmolčić et al , 2015Smolčić 2009;Smolčić & Riechers 2011).…”

Section: Introductionmentioning

confidence: 99%

The VLA-COSMOS 3 GHz Large Project: Continuum data and source catalog release

Smolčić

Novak

Bondì

et al. 2017

A&A

285

361

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We present the VLA-COSMOS 3 GHz Large Project based on 384 h of observations with the Karl G. Jansky Very Large Array (VLA) at 3 GHz (10 cm) toward the two square degree Cosmic Evolution Survey (COSMOS) field. The final mosaic reaches a median rms of 2.3 µJy beam −1 over the two square degrees at an angular resolution of 0.75 . To fully account for the spectral shape and resolution variations across the broad (2 GHz) band, we image all data with a multiscale, multifrequency synthesis algorithm. We present a catalog of 10 830 radio sources down to 5σ, out of which 67 are combined from multiple components. Comparing the positions of our 3 GHz sources with those from the Very Long Baseline Array (VLBA)-COSMOS survey, we estimate that the astrometry is accurate to 0.01 at the bright end (signal-to-noise ratio, S /N 3 GHz > 20). Survival analysis on our data combined with the VLA-COSMOS 1.4 GHz Joint Project catalog yields an expected median radio spectral index of α = −0.7. We compute completeness corrections via Monte Carlo simulations to derive the corrected 3 GHz source counts. Our counts are in agreement with previously derived 3 GHz counts based on single-pointing (0.087 square degrees) VLA data. In summary, the VLA-COSMOS 3 GHz Large Project simultaneously provides the largest and deepest radio continuum survey at high (0.75 ) angular resolution to date, bridging the gap between last-generation and next-generation surveys.

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“…Because this accretion process is radiatively inefficient, halo-fed radio galaxies often lack the luminous emission lines, X-ray emission and infrared torus emission generally associated with AGN (e.g. Laing et al 1994;Evans et al 2006;Whysong & Antonucci 2004). Therefore, they have been referred to as "radio-mode" or "low-excitation" radio galaxies (LERGs).…”

Section: Introductionmentioning

confidence: 99%

The triggering probability of radio-loud AGN

Janssen

Röttgering

Best

et al. 2012

A&A

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Low luminosity radio-loud active galactic nuclei (AGN) are generally found in massive red elliptical galaxies, where they are thought to be powered through gas accretion from their surrounding hot halos in a radiatively inefficient manner. These AGN are often referred to as "low-excitation" radio galaxies (LERGs). When radio-loud AGN are found in galaxies with a young stellar population and active star formation, they are usually high-power radiatively-efficient radio AGN ("high-excitation", HERG). Using a sample of low-redshift radio galaxies identified within the Sloan Digital Sky Survey (SDSS), we determine the fraction of galaxies that host a radio-loud AGN, f RL , as a function of host galaxy stellar mass, M * , star formation rate, color (defined by the 4000 Å break strength), radio luminosity and excitation state (HERG/LERG). We find the following: 1. LERGs are predominantly found in red galaxies. 2. The radio-loud AGN fraction of LERGs hosted by galaxies of any color follows a f LE RL ∝ M 2.5 * power law. 3. The fraction of red galaxies hosting a LERG decreases strongly for increasing radio luminosity. For massive blue galaxies this is not the case. 4. The fraction of green galaxies hosting a LERG is lower than that of either red or blue galaxies, at all radio luminosities. 5. The radio-loud AGN fraction of HERGs hosted by galaxies of any color follows a f LE RL ∝ M 1.5 * power law. 6. HERGs have a strong preference to be hosted by green or blue galaxies. 7. The fraction of galaxies hosting a HERG shows only a weak dependence on radio luminosity cut. 8. For both HERGs and LERGs, the hosting probability of blue galaxies shows a strong dependence on star formation rate. This is not observed in galaxies of a different color. Our interpretation of these results is that the presence of cold gas in a LERG enhances the probability that its SMBH becomes a luminous radio-loud AGN compared to the typical "model" LERG in a red elliptical galaxy. If enough cold gas can be transported to the SMBH a HERG can be created. However, the presence of cold gas does not automatically imply a HERG will be created. We speculate that feedback of the enhanced AGN activity in blue galaxies is responsible for the reduced probability of green galaxies to host a LERG.

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ChandraandXMM‐NewtonObservations of a Sample of Low‐Redshift FR I and FR II Radio Galaxy Nuclei

Cited by 187 publications

References 69 publications

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

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

The VLA-COSMOS 3 GHz Large Project: Continuum data and source catalog release

The triggering probability of radio-loud AGN

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