The nature of the near-infrared core source in 3C 433

Gutierrez, Eliana Battaggia; Tadhunter, C. N.; Axon, D. J.; Batcheldor, D.; Young, S.; Packham, C.; Sparks, W. B.

doi:10.1111/j.1365-2966.2009.15417.x

Cited by 7 publications

(16 citation statements)

References 45 publications

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“…It is worth mentioning that the correction for starlight for 3C 192 is the largest in the sample (P int = 60P). The estimated dichroic extinction for 3C 433 (see Ramírez et al 2009) and 3C 405 (Tadhunter et al 2000) fits very well with the mean of the other extinction estimations. For the rest of the sources, the dichroic efficiency must be at the upper limit deduced for stars in the Milky Way, regardless of how the level of extinction is estimated.…”

Section: Dichroic Extinctionsupporting

confidence: 77%

“…Studies at the K-band of the nuclear polarization of Centaurus A and Cygnus A show high core polarizations of 9 ± 1 and 28 ± 1 per cent, respectively, with the electric vector (E-vector) position angle (PA) aligned perpendicular to the radio jet (Bailey et al 1986;Tadhunter et al 2000). A similar configuration is found in 3C 223.1 and 3C 433 at 2.2 and 2.05 µm, respectively: polarization E-vectors perpendicular to the radio jet axis, in addition to dust lanes orientated perpendicular to the radio jets (Antonucci & Barvainis 1990;Ramírez et al 2009). This is consistent with a dichroic 1 or scattering origin for the polarization, since such mechanisms can produce polarization PAs that are perpendicular to the radio jet orientation.…”

mentioning

confidence: 77%

“…Our detailed study of 3C 433 (Ramírez et al 2009) suggested that the near-IR polarization of the core (8.6 ± 1.0 per cent) is produced by highly efficient dichroic extinction (A V ≈ 15 mag). Moreover, the polarized core in Cygnus A (28 ± 1 per cent; Tadhunter et al 2000), could also be explained in terms of in a similar fashion.…”

mentioning

confidence: 85%

“…The spacing of the chop in the Y direction was 31.5 to 35.5 arcsec, and the dither spacing in the X direction was 0.9 arcsec. A total on-galaxy integration time of 1024 s (4 dithers of 256 s each: ∼0.5 orbits in total) for each POL-L filters was achieved, with the exception of the relatively bright source 3C 433, for which shorter exposure times and more dithers were used in order to avoid saturation (4 dithers of 16 s each, and 12 dithers of 64 s each, for each POL-L filters; more details in Ramírez et al 2009). Similar off-galaxy background exposures were used to facilitate accurate background subtraction without compromising the signal-to-noise ratio in the nuclear regions of the galaxies.…”

Section: S a M P L E A N D O B S E Rvat I O N Smentioning

confidence: 99%

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Near-infrared Hubble Space Telescope polarimetry of a complete sample of narrow-line radio galaxies

Gutierrez¹,

Tadhunter²,

Axon³

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We present an analysis of 2.05 µm Hubble Space Telescope polarimetric data for a sample of 13 nearby Fanaroff-Riley type II (FRII) 3CR radio sources (0.03 < z < 0.11) that are classified as narrow-line radio galaxies (NLRG) at optical wavelengths. We find that the compact cores of the NLRG in our sample are intrinsically highly polarized in the near-infrared (near-IR) (6 < P 2.05 µm < 60 per cent), with the electric vector (E-vector) perpendicular to the radio axis in 54 per cent of the sources. The levels of extinction required to produce near-IR polarization by the dichroic extinction mechanism are consistent with the measured values recently reported in Ramírez et al., provided that this mechanism has its maximum efficiency. This consistency suggests that the nuclear polarization could be due to dichroic extinction. In this case, toroidal magnetic fields that are highly coherent would be required in the circumnuclear tori to align the elongated dust grains responsible for the dichroic extinction. However, it is not entirely possible to rule out other polarization mechanisms (e.g. scattering, synchrotron emission) with our observations at only one near-IR wavelength. Therefore, further polarimetry observations at mid-IR and radio wavelengths will be required to test whether all the near-IR polarization is due to dichroic extinction.

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Section: Dichroic Extinctionsupporting

confidence: 77%

mentioning

confidence: 77%

mentioning

confidence: 85%

Section: S a M P L E A N D O B S E Rvat I O N Smentioning

confidence: 99%

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Near-infrared Hubble Space Telescope polarimetry of a complete sample of narrow-line radio galaxies

Gutierrez¹,

Tadhunter²,

Axon³

et al. 2014

Monthly Notices of the Royal Astronomical Society

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“…While for the other classes of 3CR galaxies the nuclear sources are directly associated with the AGN (and thus effectively point-like at our resolution), for HIGs our results suggest that they are in general dominated by scattered light, a spatially resolved component. This is confirmed by several observations of imaging polarimetry and spectropolarimetry of radio galaxies (e.g., Tadhunter et al 2000;Ramirez et al 2009). We then re-modeled the observed NIR brightness profiles taking into account the possibility that the central HIG sources are actually resolved and can be described by a Gaussian light distribution.…”

Section: Fr Ii: High-ionization Galaxies (Higs)supporting

confidence: 65%

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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Radio AGN in the local universe: unification, triggering and evolution

Tadhunter

2016

Astron Astrophys Rev

138

148

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Associated with one of the most important forms of active galactic nucleus (AGN) feedback, and showing a strong preference for giant elliptical host galaxies, radio AGN (L_1.4GHz > 10^24 W Hz^-1) are a key sub-class of the overall AGN population. Here I review our current state of understanding of the population of radio AGN at low and intermediate redshifts (z < 0.7), concentrating on their AGN and host galaxy properties, and covering three interlocking themes: the classification of radio AGN and its interpretation; the triggering and fuelling of the jet and AGN activity; and the evolution of the host galaxies. I show that much of the observed diversity in the AGN properties of radio AGN can be explained in terms of a combination of orientation/anisotropy, mass accretion rate, and variability effects. The detailed morphologies of the host galaxies are consistent with the triggering of strong-line radio galaxies (SLRG) in galaxy mergers. However, the star formation properties and cool ISM contents suggest that the triggering mergers are relatively minor in terms of their gas masses in most cases, and would not lead to major growth of the supermassive black holes and stellar bulges; therefore, apart from a minority (<20%) that show evidence for higher star formation rates and more massive cool ISM reservoirs, the SLRG represent late-time re-triggering of activity in mature giant elliptical galaxies. In contrast, the host and environmental properties of weak-line radio galaxies (WLRG) with Fanaroff-Riley class I (FRI) radio morphologies are consistent with more gradual fuelling of the activity via gas accretion at low rates onto the supermassive black holes.Comment: Accepted for publication in Astronomy & Astrophysics Review, 67 pages, 17 figure

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The nature of the near-infrared core source in 3C 433

Cited by 7 publications

References 45 publications

Near-infrared Hubble Space Telescope polarimetry of a complete sample of narrow-line radio galaxies

Near-infrared Hubble Space Telescope polarimetry of a complete sample of narrow-line radio galaxies

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

Radio AGN in the local universe: unification, triggering and evolution

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