Deep spectroscopy of the FUV-optical emission lines from a sample of radio galaxies at z~2.5: metallicity and ionization

Abstract

We present long-slit NIR spectra, obtained using the ISAAC instrument at the Very Large Telescope, for nine radio galaxies at z~2.5. One-dimensional spectra have been extracted and cross calibrated with optical spectra from the literature to produce line spectra spanning a rest wavelength of ~1200-7000 A. We have also produced a composite of the rest-frame UV-optical line fluxes of powerful, z~2.5 radio galaxies. We have investigated the relative strengths of Ly-alpha, H-beta, H-alpha, HeII 1640 and HeII 4687, and we find that Av can vary significantly from object to object. In addition, we identify new line ratios to calculate electron temperature: [NeV] 1575/[NeV] 3426, [NeIV] 1602/[NeIV] 2423, OIII] 1663/[OIII] 5008 and [OII] 2471/[OII]3728. We model the emission line spectra and conclude they are best explained by AGN-photoionization with the ionization parameter U varying between objects. Single slab photoionization models are unable to reproduce the high- and the low-ionization lines simultaneously: this may be alleviated either by combining two or more single slab photoionization models with different U, or by using mixed-medium models such as those of Binette, Wilson & Storchi-Bergmann (1996). On the basis of NV/NIV] and NIV]/CIV we argue that shocks make a fractional contribution to the ionization of the EELR. We find that in the EELR of z~2 radio galaxies the N/H abundance ratio is close to its solar value. We conclude that N/H and metallicity do not vary by more than a factor of two in our sample. This is consistent with the idea that massive ellipticals are assembled very early in the history of the universe, and then evolve relatively passively up to the present day.

Accepted for publication by MNRAS

References in corpus (4)

• The Massive Hosts of Radio Galaxies Across Cosmic Time
• Ly-alpha excess in high redshift radio galaxies: a signature of star formation
• Jet-gas interactions in z~2.5 radio galaxies: evolution of the ultraviolet line and continuum emission with radio morphology
• An extreme rotation measure in the high-redshift radio galaxy PKS B0529-549

Cited by in corpus (37)

• Evidence for powerful AGN winds at high redshift: Dynamics of galactic outflows in radio galaxies during the "Quasar Era"
• The large and small scale properties of the intergalactic gas in the Slug Ly-alpha nebula revealed by MUSE HeII emission observations
• Inspiraling Halo Accretion Mapped in Lyman-$\alpha$ Emission around a $z\sim 3$ Quasar
• Rapidly growing black holes and host galaxies in the distant Universe from the Herschel Radio Galaxy Evolution Project
• The SINFONI survey of powerful radio galaxies at z~2: Jet-driven AGN feedback during the Quasar Era
• Obscured AGN at 1.5 < z < 3.0 from the zCOSMOS-deep Survey I. Properties of the emitting gas in the Narrow Line Region
• A Deep Narrowband Imaging Search for CIV and He II Emission from Ly$\alpha$ Blobs
• Optical and mid-infrared line emission in nearby Seyfert galaxies
• The 700 ks Chandra Spiderweb Field II: Evidence for inverse-Compton and thermal diffuse emission in the Spiderweb galaxy
• The peculiar emission line spectra of core-Extremely Red BOSS Quasars at $z\sim$2-3: orientation and/or evolution?
• Evidence for Very Massive Stars in extremely UV-bright star-forming galaxies at $z\sim 2.2-3.6$
• The interstellar medium and feedback in the progenitors of the compact passive galaxies at z~2
• A 100 kpc nebula associated with the "Teacup" fading quasar
• Emission line activity in type 2 quasars from the Sloan Digital Sky Survey
• Probing the AGN Unification Model at redshift z $\sim$ 3 with MUSE observations of giant Ly$\alpha$ nebulae
• Quenching by gas compression and consumption: A case study of a massive radio galaxy at z = 2.57
• The extent of ionization in simulations of radio-loud AGNs impacting kpc gas discs
• Feeding the spider with carbon -- [CII] emission from the circum galactic medium and active galactic nucleus
• The MUSE 3D view of feedback in a high-metallicity radio galaxy at z = 2.9
• Mapping the "invisible" circumgalactic medium around a z $\sim$ 4.5 radio galaxy with MUSE
• MUSE unravels the ionisation and origin of metal enriched absorbers in the gas halo of a z = 2.92 radio galaxy
• Scrutiny of a very young, metal-poor star-forming Lyα-emitter at z ~ 3.7
• Ionization and feedback in Ly$\alpha$ halos around two radio galaxies at z$\sim$2.5
• Stellar feedback in a clumpy galaxy at $z\sim$ 3.4
• Constraints on the densities and temperature of Seyfert 2 NLR
• Extreme CII emission in type 2 quasars at z~2.5: a signature of kappa-distributed electron energies?
• OV] $\lambda \lambda$1213.8,1218.3 emission from extended nebulae around quasars: contamination of Ly$\alpha$ and a new diagnostic for AGN activity in Ly$\alpha$-emitters
• Multi-line assessment of narrow-line regions in $z\sim$ 3 radio galaxies
• Electron Energy Distributions in the Extended Gas Nebulae associated with High-z AGN: Maxwell-Boltzmann vs. kappa distributions
• Integral Field Spectroscopy of two radio galaxies at z~2.3
• Spatially extended absorption around the z=2.63 radio galaxy MRC 2025-218: outflow or infall?
• UV and optical emission lines from the z=2.6 radio galaxy 0828+193: spatially resolved measurements
• A candidate quadruple AGN system at $z\sim 3$
• Witnessing the transformation of a quasar host galaxy at z=1.6
• Carbon-loud SDSS BOSS QSO2s at z > 2: High density gas or secondary production of Carbon?
• Exploring the gaseous halos of z>3 radio galaxies with UVES and JWST/NIRSpec
• Modelling observable signatures of jet-ISM interaction: thermal emission and gas kinematics