2000MNRAS.317....9W

We present near-infrared spectra of seven radio-loud quasars with a median redshift of 2.1, five of which were previously known to have Lyα nebulae. Extended [Oiii] λ5007 and Hα emission are evident around six objects, at the level of a few times 10^–16erg.cm^–2.arcsec^–2.s^–1 within ≃2arcsec of the nucleus (≡16kpc in the adopted cosmology). Nuclear [Oii] λ3727 is detected in three of the five quasars studied at this wavelength and clearly extended in one of them.

The extended [Oiii] tends to be brighter on the side of the nucleus with the stronger, jet-like radio emission, indicating at least that the extranuclear gas is distributed anisotropically. It is also typically redshifted by several hundred km.s^–1 from the nuclear [Oiii], perhaps because of the latter being blueshifted from the host galaxy's systemic velocity. Alternatively, the velocity shifts could be due to infall (which is suggested by linewidths ∼1000km.s^–1 FWHM) in combination with a suitable dust geometry. Lyα/Hα ratios well below the case B value suggest that some dust is present.

Photoionization modelling of the [Oiii]/[Oii] ratios in the extended gas suggests that its pressure is around or less than a few times 10⁷cm^–3.K; any confining intracluster medium is thus likely to host a strong cooling flow. A comparison with lower redshift work suggests that there has been little evolution in the nuclear emission-line properties of radio-loud quasars between redshifts 1 and 2.