<i>K</i>-band polarimetry of seven high-redshift radio galaxies

Leyshon, Gareth; Eales, Stephen Anthony

doi:10.1046/j.1365-8711.1998.29511145.x

Cited by 17 publications

(30 citation statements)

References 21 publications

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“…Although radio-quiet obscured quasars have not been studied in detail to assess the AGN light contribution to the rest-frame near-infrared emission, some work has been performed on high-redshift radio galaxies. Leyshon & Eales (1998) and Leyshon et al (1999) show that the majority high-redshift radio galaxies have only weak polarization in the near-infrared, indicating little scattered light at those wavelengths. Seymour et al (2007) and de Breuck et al (2010) studied high-redshift radio galaxies with Spitzer and demonstrated the practicality of separating the AGN and stellar emission in such objects by modeling the AGN emission and fitting a simple stellar SED, in a similar manner to the fitting done in this paper.…”

Section: Stellar Luminositiesmentioning

confidence: 99%

THE STELLAR, MOLECULAR GAS, AND DUST CONTENT OF THE HOST GALAXIES OF TWOz∼ 2.8 DUST-OBSCURED QUASARS

Lacy

Petric

Martínez‐Sansigre

et al. 2011

The Astronomical Journal

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We present optical through radio observations of the host galaxies of two dust-obscured, luminous quasars selected in the mid-infrared, at z = 2.62 and z = 2.99, including a search for CO emission. Our limits on the CO luminosities are consistent with these objects having masses of molecular gas 10 10 M , several times less than those of luminous submillimeter-detected galaxies at comparable redshifts. Their near-infrared spectral energy distributions, however, imply that these galaxies have high stellar masses (∼10 11 -10 12 M ). The relatively small reservoirs of molecular gas and low dust masses are consistent with them being relatively mature systems at high-z.

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Section: Stellar Luminositiesmentioning

confidence: 99%

THE STELLAR, MOLECULAR GAS, AND DUST CONTENT OF THE HOST GALAXIES OF TWOz∼ 2.8 DUST-OBSCURED QUASARS

Lacy

Petric

Martínez‐Sansigre

et al. 2011

The Astronomical Journal

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“…This continuum polarization rises toward the blue, reaching P % 15% for the northern component. Observations with the UK Infrared Telescope by Leyshon & Eales (1998) show …”

Section: C 356mentioning

confidence: 99%

Radio Galaxies atz= 1.1 to 3.8: Adaptive Optics Imaging and ArchivalHubble Space TelescopeData

Steinbring

Crampton

Hutchings

2002

ApJ

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We have undertaken a program of high-resolution imaging of high-redshift radio galaxies (HzRGs), using adaptive optics on the Canada-France-Hawaii Telescope. We report on deep imaging in J, H, and K bands of six HzRGs in the redshift range 1.1 to 3.8. At these redshifts, near-infrared bandpasses sample the rest-frame visible galactic light. The radio galaxy is resolved in all the fields and is generally elongated along the axis of the radio lobes. These images are compared with archival Hubble Space Telescope Wide-Field Planetary Camera 2 optical observations of the same fields and show that the HzRG morphology in rest-frame ultraviolet and visible light is generally very similar: a string of bright compact knots. Furthermore, this samplealthough very small-suggests that the colors of the knots are consistent with light from young stellar populations. If that is the case, a plausible explanation is that these objects are being assembled by mergers at high redshift.

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“…Recent discussions of these possibilities can be found in Eales et al (1997), Best, Longair & Röttgering (1998) and Roche, Eales & Rawlings (1998). Although there is direct observational evidence from near‐infrared polarimetry (Leyshon & Eales 1998) that scattered light makes only a small (few per cent) contribution to the near‐infrared luminosity of radio galaxies even when it makes a very significant contribution in the ultraviolet and optical, it has not yet been conclusively shown that reddened quasar light is also a negligible component. As illustrated by Fig.…”

Section: Introductionmentioning

confidence: 99%

Thermal-infrared imaging of 3C radio galaxies at z 1

Simpson

Rawlings

Lacy

1999

Monthly Notices of the Royal Astronomical Society

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We present the results of a programme of thermal‐infrared imaging of 19 z∼ 1 radio galaxies from the 3CR and 3CRR (LRL) samples. We detect emission at L′ (3.8 μm) from four objects; in each case the emission is unresolved at 1‐arcsec resolution. 15 radio galaxies remain undetected to sensitive limits of L′≈ 15.5. Using these data in tandem with archived HST data and near‐infrared spectroscopy, we show that three of the detected ‘radio galaxies’ (3C 22, 3C 41 and 3C 65) harbour quasars reddened by AV≲ 5 mag. Correcting for this reddening, 3C 22 and 3C 41 are very similar to coeval 3C quasars, whilst 3C 65 seems unusually underluminous. The fourth radio galaxy detection (3C 265) is a more highly obscured (AV∼ 15) but otherwise typical quasar, which previously has been evident only in scattered light. We determine the fraction of dust‐reddened quasars at z∼ 1 to be 28−13+25 per cent at 90 per cent confidence. On the assumption that the undetected radio galaxies harbour quasars similar to those in 3C 22, 3C 41 and 3C 265 (as seems reasonable, given their similar narrow emission line luminosities) we deduce extinctions of AV≳: 15 towards their nuclei. The contributions of reddened quasar nuclei to the total K‐band light range from ∼0 per cent for the non‐detections, through ∼10 per cent for 3C 265 to ∼80 per cent for 3C 22 and 3C 41. Correcting for these effects does not remove the previously reported differences between the K magnitudes of 3C and 6C radio galaxies, so contamination by reddened quasar nuclei is not a serious problem for drawing cosmological conclusions from the K–z relation for radio galaxies. We discuss these results in the context of the ‘receding torus’ model which predicts a small fraction of lightly reddened quasars in samples of high‐radio‐luminosity sources. We also examine the likely future importance of thermal‐infrared imaging in the study of distant powerful radio sources.

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K-band polarimetry of seven high-redshift radio galaxies

Cited by 17 publications

References 21 publications

THE STELLAR, MOLECULAR GAS, AND DUST CONTENT OF THE HOST GALAXIES OF TWOz∼ 2.8 DUST-OBSCURED QUASARS

THE STELLAR, MOLECULAR GAS, AND DUST CONTENT OF THE HOST GALAXIES OF TWOz∼ 2.8 DUST-OBSCURED QUASARS

Radio Galaxies atz= 1.1 to 3.8: Adaptive Optics Imaging and ArchivalHubble Space TelescopeData

Thermal-infrared imaging of 3C radio galaxies at z 1

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