The Nuclei of Radio Galaxies in the Ultraviolet: The Signature of Different Emission Processes

Chiaberge, M.; Macchetto, F.; Sparks, W. B.; Capetti, A.; Allen, M. G.; Martel, A. R.

doi:10.1086/339846

Cited by 69 publications

(98 citation statements)

References 25 publications

(40 reference statements)

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“…While the first case is rather obvious, the second situation 5 indicates that the gas responsible for the X-ray absorption shares the flattened distribution of the dust, inducing a dependence of N H on the viewing angle. Note that evidence of a dependence of absorption on orientation in FR I nuclei was 5 This behaviour is also shared by the radio-galaxy B2 0055+30, with a large column density N H ∼ 7 × 10 22 cm −2 (Donato et al 2004) associated to a highly inclined disk in the HST image (Capetti et al 2000a). already found by Chiaberge et al (2002) from the comparison of the optical and UV images of radio-galaxies.…”

Section: The X-ray Absorbing Medium In Fr I Nucleisupporting

confidence: 51%

The Chandra view of the 3C/FR I sample of low luminosity radio-galaxies

Balmaverde¹,

Capetti²,

Grandi³

2006

A&A

124

110

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We present results from Chandra observations of the 3C/FR I sample of low luminosity radio-galaxies. We detected a power-law nuclear component in 12 objects out of the 18 with available data. In 4 galaxies we detected nuclear X-ray absorption at a level of N H ∼ (0.2−6) × 10 22 cm −2 . X-ray absorbed sources are associated with the presence of highly inclined dusty disks (or dust filaments projected onto the nuclei) seen in the HST images. This suggests the existence of a flattened X-ray absorber, but of much lower optical depth than in classical obscuring tori. We thus have an unobstructed view toward most FR I nuclei, while absorption plays only a marginal role in the remaining objects. Three pieces of evidence support a jet origin for the X-ray cores: i) the presence of strong correlations between the nuclear luminosities in the radio, optical, and X-ray bands, extending over 4 orders of magnitude and having a much smaller dispersion (∼0.3 dex) when compared to similar trends found for other classes of AGNs, all of which points to a common origin for the emission in the three bands; ii) the close similarity of the broad-band spectral indices with the sub-class of BL Lac objects sharing the same range of extended radio-luminosity, in accord with the FR I/BL Lacs unified model; iii) the presence of a common luminosity evolution of spectral indices in both FR I and BL Lacs. The low luminosities of the X-ray nuclei, regardless of their origin, strengthens the interpretation of low efficiency accretion in low luminosity radio-galaxies.

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Section: The X-ray Absorbing Medium In Fr I Nucleisupporting

confidence: 51%

The Chandra view of the 3C/FR I sample of low luminosity radio-galaxies

Balmaverde¹,

Capetti²,

Grandi³

2006

A&A

124

110

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“…Thus, the most likely explanation for the scatter is that the variability of the nuclei plays a fundamental role, while the effect of absorption is less significant. Indeed, this is supported by the variability observed for the nuclear flux of 3C 317 (Chiaberge et al 2002b) and of 3C 274 (Tsvetanov et al 1998;Perlman et al 2003). Conversely, the presence of dust appears to play a role in dimming the nuclear flux on the UV (Chiaberge et al 2002b).…”

Section: Fr I Galaxiesmentioning

confidence: 81%

THE 1.6 μm NEAR-INFRARED NUCLEI OF 3C RADIO GALAXIES: JETS, THERMAL EMISSION, OR SCATTERED LIGHT?

Baldi¹,

Chiaberge²,

Capetti³

et al. 2010

ApJ

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Using HST NICMOS 2 observations we have measured 1.6 μm near-infrared nuclear luminosities of 100 3CR radio galaxies with z < 0.3, by modeling and subtracting the extended emission from the host galaxy. We performed a multiwavelength statistical analysis (including optical and radio data) of the properties of the nuclei following classification of the objects into FR I and FR II, and low-ionization galaxies (LIGs), high-ionization galaxies (HIGs), and broad-line objects (BLOs) using the radio morphology and optical spectra, respectively. The correlations among near-infrared, optical, and radio nuclear luminosity support the idea that the nearinfrared nuclear emission of FR Is has a non-thermal origin. Despite the difference in radio morphology, the multiwavelength properties of FR II LIG nuclei are statistically indistinguishable from those of FR Is, an indication of a common structure of the central engine. All BLOs show an unresolved near-infrared nucleus and a large near-infrared excess with respect to FR II LIGs and FR Is of equal radio core luminosity. This requires the presence of an additional (and dominant) component other than the non-thermal light. Considering the shape of their spectral energy distribution, we ascribe the origin of their near-infrared light to hot circumnuclear dust. A near-infrared excess is also found in HIGs, but their nuclei are substantially fainter than those of BLO. This result indicates that substantial obscuration along the line of sight to the nuclei is still present at 1.6 μm. Nonetheless, HIG nuclei cannot simply be explained in terms of dust obscuration: a significant contribution from light reflected in a circumnuclear scattering region is needed to account for their multiwavelength properties.

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“…The published results, corrected for Galactic extinction are plotted in Figure 2 (Chiaberge et al 1999(Chiaberge et al , 2002Prieto et al 2016). The data is non-simultaneous and is distributed from 1995 -2003.…”

Section: Constraining the Broadband Spectrummentioning

confidence: 99%

A Jet Source of Event Horizon Telescope Correlated Flux in M87

Punsly

2017

ApJ

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Event Horizon Telescope (EHT) observations at 230 GHz are combined with Very Long Baseline Interferometry (VLBI) observations at 86 GHz and high resolution Hubble Space Telescope optical observations in order to constrain the broadband spectrum of the emission from the base of the jet in M87. The recent VLBI observations of Hada et al provide much stricter limits on the 86 GHz luminosity and component acceleration in the jet base than was available to previous modelers. They reveal an almost hollow jet on sub-mas scales. Thus, tubular models of the jet base emanating from the innermost accretion disk are considered within the region responsible for the EHT correlated flux. There is substantial synchrotron self absorbed opacity at 86 GHz. A parametric analysis indicates that the jet dimensions and power depend strongly on the 86 GHz flux density and the black hole spin, but weakly on other parameters such as jet speed, 230 GHz flux density and optical flux. The entire power budget of the M87 jet, 10 44 ergs/sec, can be accommodated by the tubular jet. No invisible, powerful spine is required. Even though this analysis never employs the resolution of the EHT, the spectral shape implies a dimension transverse to the jet direction of 12-21 µas (∼24-27 µas) for 0.99 > a/M > 0.95 (a/M ∼ 0.7), where M is the mass and a is the angular momentum per unit mass of the central black hole.

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The Nuclei of Radio Galaxies in the Ultraviolet: The Signature of Different Emission Processes

Cited by 69 publications

References 25 publications

The Chandra view of the 3C/FR I sample of low luminosity radio-galaxies

The Chandra view of the 3C/FR I sample of low luminosity radio-galaxies

THE 1.6 μm NEAR-INFRARED NUCLEI OF 3C RADIO GALAXIES: JETS, THERMAL EMISSION, OR SCATTERED LIGHT?

A Jet Source of Event Horizon Telescope Correlated Flux in M87

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