TY  - JOUR
EP  - 756
IS  - 1
AV  - public
SN  - 0035-8711
TI  - Polycyclic aromatic hydrocarbon emission in powerful high-redshift radio galaxies
KW  - Galaxies: active
KW  -  galaxies: high-redshift
KW  -  galaxies: nuclei
KW  -  quasars: general
KW  -  galaxies: star formation
KW  -  ACTIVE GALACTIC NUCLEI
KW  -  ULTRALUMINOUS INFRARED GALAXIES
KW  -  SPITZER-SPACE-TELESCOPE
KW  -  STAR-FORMING GALAXIES
KW  -  MOLECULAR-HYDROGEN EMISSION
KW  -  SUPERMASSIVE BLACK-HOLES
KW  -  M SILICATE ABSORPTION
KW  -  EXTENDED IONIZED-GAS
KW  -  DEEP FIELD-SOUTH
KW  -  AGN DUSTY TORI
N1  - This version is the version of record. For information on re-use, please refer to the publisher?s terms and conditions.
ID  - discovery1387398
UR  - http://dx.doi.org/10.1093/mnras/sts368
N2  - We present the mid-infrared (IR) spectra of seven of the most powerful radio-galaxies known
to exist at 1.5 < z < 2.6. The radio emission of these sources is dominated by the AGN with
500 MHz luminosities in the range 1027.8?1029.1 W Hz?1. The AGN signature is clearly evident
in the mid-IR spectra; however, we also detect polycyclic aromatic hydrocarbon emission,
indicative of prodigious star formation at a rate of up to ?1000 M yr?1. Interestingly, we
observe no significant correlation between AGN power and star formation in the host galaxy.
We also find most of these radio galaxies to have weak 9.7 µm silicate absorption features
(?9.7 µm < 0.8) which implies that their mid-IR obscuration is predominantly due to the dusty
torus that surrounds the central engine, rather than the host galaxy. The tori are likely to have
an inhomogeneous distribution with the obscuring structure consisting of individual clouds.
We estimate that these radio galaxies have already formed the bulk of their stellar mass and
appear to lie at a stage in their evolution where the obscured AGN dominates the energy output
of the system but star formation is also prevalent.
Y1  - 2013/02/01/
A1  - Rawlings, JI
A1  - Seymour, N
A1  - Page, MJ
A1  - De Breuck, C
A1  - Stern, D
A1  - Symeonidis, M
A1  - Appleton, PN
A1  - Dey, A
A1  - Dickinson, M
A1  - Huynh, M
A1  - Le Floc'h, E
A1  - Lehnert, M
A1  - Mullaney, JR
A1  - Nesvadba, N
A1  - Ogle, P
A1  - Sajina, A
A1  - Vernet, J
A1  - Zirm, A
JF  - Monthly Notices of the Royal Astronomical Society
PB  - OXFORD UNIV PRESS
SP  - 744
VL  - 429
ER  -