Spectroscopy of 7 Radio-Loud QSOs at 2<z<6: Giant Lyman-alpha Nebulae Accreting onto Host Galaxies

Abstract

We performed long-slit optical spectroscopy (GTC-OSIRIS) of 6 radio-loud QSOs at redshifts $2<z<3$, known to have giant ($\sim 50$-100 kpc) Lyman-$\alpha$ emitting nebulae, and detect extended Lyman-$\alpha$ emission for 4, with surface brightness $\sim 10^{-16}$ ergs $\mathrm{c}{\mathrm{m}}^{-2}{\mathrm{s}}^{-1}\mathrm{arcse}{\mathrm{c}}^{-2}$ and line width FWHM 400-1100 (mean 863) km ${\mathrm{s}}^{-1}$. We also observed the $z\simeq 5.9$ radio-loud QSO, SDSS J2228+0110, and find evidence of a $\ge 10$ kpc extended Lyman-$\alpha$ emission nebula, a new discovery for this high-redshift object. Spatially-resolved kinematics of the 5 nebulae are examined by fitting the Lyman-$\alpha$ wavelength at a series of positions along the slit. We found the line-of-sight velocity $\Delta (v)$ profiles to be relatively flat. However, 3 of the nebulae appear systematically redshifted by 250-460 km ${\mathrm{s}}^{-1}$ relative to the Lyman-$\alpha$ line of the QSO (with no offset for the other two), which we argue is evidence for infall. One of these (Q0805+046) had a small ($\sim 100$ km ${\mathrm{s}}^{-1}$) velocity shift across its diameter and a steep gradient at the centre. Differences in line-of-sight kinematics between these 5 giant nebulae and similar nebulae associated with high-redshift radio galaxies (which can show steep velocity gradients) may be due to an orientation effect, which brings infall/outflow rather than rotation into greater prominence for the sources observed `on-axis' as QSOs.

16 pages, 15 figures, accepted for publication in MNRAS

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Cited by in corpus (10)

• Inspiraling Halo Accretion Mapped in Lyman-$\alpha$ Emission around a $z\sim 3$ Quasar
• The REQUIEM Survey I: A Search for Extended Ly-Alpha Nebular Emission Around 31 z>5.7 Quasars
• Mapping the Lyman-Alpha Emission Around a z~6.6 QSO with MUSE: Extended Emission and a Companion at Close Separation
• Deciphering Lyman $\alpha$ blob 1 with deep MUSE observations
• Where is the fuzz? Undetected Lyman alpha nebulae around QSOs at z~2.3
• Cold Mode Gas Accretion on Two Galaxy Groups at z$\sim$2
• Spatially resolved Lyman-$\alpha$ emission around radio bright quasars
• A survey of Ly$\alpha$ emission around Damped Ly$\alpha$ absorbers at $z\approx 2$ with the Keck Cosmic Web Imager
• The host galaxies of radio-loud quasars at z>5 with ALMA
• The Decoupled Kinematics of high-z QSO Host Galaxies and their Lya halos