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Research Activities
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My research covers a wide range of extragalactic
observational astronomy, including:
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Active Galactic Nuclei (AGN):
My interests lie in understanding the AGN phenomenon, and its
connection to the formation and evolution of normal
galaxies. This interest dates back to my PhD research, when I
used the Hubble Space Telescope to study the interactions
between powerful distant radio sources and both their host
galaxies and the surrounding gas, showing that the interactions
are particularly strong in young (small) radio galaxies. More
recently, I have been carrying out large statistical studies of
the host galaxies of AGN in the nearby Universe, using radio
galaxies in the 2dF Galaxy Redshift Survey and the Sloan
Digitised Sky Survey. Using these, I have shown that feedback
from radio-loud AGN can control the rate of growth of massive
elliptical galaxies.
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LOFAR:
LOFAR is a new
radio telescope under construction in the Netherlands and
around Europe, due to commence operations later in 2011. It
will open up a completely new low-frequency radio regime, as
well as offering the deepest large-sky area radio surveys prior
to the Square Kilometer Array. I assembled the UK's
Scientific
White Paper, and have recently taken over as PI of
LOFAR-UK, which is a
consortium of over 20 Universities coordinating the UK's
efforts in LOFAR. I am a member of the LOFAR International
Telescope Board, and a core member of the Key Science Project
carrying out deep Extragalactic Surveys with LOFAR. |
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HiZELS: the Hi-z
Emission Line Survey
Together with Ian Smail, I am co-leading the UKIRT large
Campaign Project HiZELS. This
project uses the wide-field near-infrared imaging capabilities
of the WFCAM telescope, together with narrow-band filters, to
select emission line galaxies across all of cosmic
time. Emission-line surveys are a particularly powerful method
for tracing the evolution of star formation (and to a lesser
extent AGN activity) as a function of cosmic epoch; sources are
identified on the strength of their emission line and thus
crudely represent a star-formation rate-selected sample, which
must lie in a narrow range in redshift. Hence, using a number
of narrow-band filters it is possible to apply a single
technique to target H-alpha emitters across a wide range of
redshifts, yielding large and representative samples at each
epoch and with a uniform selection function. Such samples are
ideal for tracing the evolution in the star-formation rate
density across the era of peak activity in galaxies, as well as
its distribution amongst the galaxy population. I am also involved in
future deep narrow-band surveys with VISTA, searching for Ly-alpha
emission line galaxies beyond redshift 7. |
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Clusters and groups
of galaxies:
I am involved in a number of studies of high-redshift clusters
of galaxies. I am carrying out searches for, and studies of,
clusters of galaxies around powerful radio sources at redshifts
above 1: these are some of the earliest clusters known in the
Universe. In addition I am part of the ESO Distant
Cluster Survey (EDisCS) consortium, which is carrying out a
detailed study of the evolution of cluster galaxies out to
redshifts of nearly one. |
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Extragalactic radio
source samples:
In order to investigate the properties and interactions of
radio sources, and the evolution of the space density of radio
sources with cosmic epoch, it is necessary to develop complete
and well-defined samples of radio sources. In the late 1990s I
developed the first spectroscopically complete sample of
powerful radio sources visible to southern hemisphere
telescopes. More recently, a long-running project has been to
develop the lower luminosity "CENSORS" radio source sample, in
order to investigate in detail the cosmic evoution of the radio
luminosity function. The faintest radio samples also allow
investigation of star-forming galaxies, and the far-IR radio
correlation.
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AGN in Clusters:
Over recent years I have been pioneering the study of low
luminosity AGN and starbursting galaxies in distant clusters of
galaxies, at radio, sub-mm and X-ray wavelengths, finding large
excesses of sources in many such clusters. We are now carrying out
a large statistical study of cluster AGN activity, based on Chandra
archive data. |
 | Other interests:
I also work on many other topics relating to cosmology
and to galaxy formation and evolution. Amongst other
activities, I am a member of the PanSTARRS deep
optical survey consortium, the SHADES and SCUBA-2
Cosmology Legacy Survey consortia for sub-mm studies,
the UltraVISTA survey team, the SERVS Spitzer
consortium, and the eMERLIN Extragalactic Survey team.
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