Integral field spectroscopy of two radio galaxies at z ˜ 2.3

Sánchez, S. F.; Humphrey, A.. Integral field spectroscopy of two radio galaxies at z ˜ 2.3. Astronomy and Astrophysics. 2009, Vol. Volume 495, Issue 2, 2009, pp.471-478, p. -2009.

Aims. In this article we study the morphology, kinematics and ionization
properties of the giant ionized gas nebulae surrounding two high
redshift radio galaxies, 4C 40.36 (z = 2.27) and 4C 48.48 (z = 2.34).
Methods: Integral field spectroscopy observations were taken using the
PPAK bundle of the PMAS spectrograph, mounted on the 3.5 m on the Calar
Alto Observatory, in order to cover a field-of-view of 64 arcsec ×
72 arcsec centered in each radio galaxy. The observations spanned 5
nights, using two different spectral resolutions (with FWHM ~ 4 Å
and ~8 Å respectively), covering the optical wavelength range from
~3700 Å to ~7100 Å, which corresponds to the rest-frame
ultraviolet range from ~1100 Å to ~2000 Å. Various emission
lines are detected within this wavelength range, including Lyα
(1216 Å), NV (1240 Å), CIV (1549 Å), HeII (1640
Å), OIII] (1663 Å) and CIII] (1909 Å). The dataset was
used to derive the spatial distribution of the flux intensity of each of
these lines and the gas kinematics. The properties of the emission lines
in the nuclear regions were studied in detail. Results: In agreement
with previous studies, we find that both objects are embedded in a large
ionized gas nebula, where Lyα emission is extended across ~100 kpc
or more. The CIV and HeII emission lines are also spatially extended.
The nebulae are generally aligned with the radio axis, although we
detect emission far from it. In 4C+48.48, there is a band of low
Lyα/CIV running perpendicular to the radio axis, at the location
of the active nucleus. This feature might be the observational signature
of an edge-on disk of neutral gas. The kinematics of both nebulae are
inconsistent with stable rotation, although they are not inconsistent
with infall or outflow.

Based on observations collected at the

Centro Astronḿico Hispano Alemán (CAHA) at Calar Alto,
operated jointly

by the Max-Planck Institut für Astronomie and the Instituto de
Astrofísica de Andalucía (CSIC).