CURRENT RESEARCH TOPICS
A selection of images to be used in two Astronomy Magazine articles are shown here. Any recent press release information will be found here. This page also includes links to a few other pretty pictures I've made along the way. A few useful rules for operating in this field are given on this page.
HiZELS
HiZELS is the first truly panoramic extragalactic narrow-band survey, roughly two-orders of magnitude larger than any similar previous study. The survey uses
the WFCAM instrument on the 3.8-m UK Infrared
Telescope (UKIRT) utilizing a set of existing
and custom-made narrow-band filters in the J, H and K-bands to detect
emission line galaxies at z = 1-9 over ~10 square degrees of extragalactic sky in the UKIDSS DXS survey regions. The survey
employs the H2(S1) narrow-band filter to target H-alpha emitting galaxies
at z=2.23. In addition, in anticipation of this survey, we have
purchased specially designed narrow-band filters targeting the [OII] emission line at
3727A and the [OIII] line at 5007A, in galaxies at the same redshift as the H-alpha
survey. Together these three sets of filters will enable
us to investigate the [OII] 3727, [OIII] 5007 and H-alpha emission from
galaxies at z=2.23, while the J- and H-band filters will deliver
identically-selected H-alpha samples at z=0.84 and 1.47 respectively. The
comparisons between the luminosity function, the clustering and
variation with environment of these H-alpha-selected samples across z=0.8-2.2 will yield unique constraints on the evolution of star-forming
galaxies. More speculatively, the J-band filter will be sensitive to
Ly-alpha emission from galaxies at z=8.90 and may detect a few such
sources if current theoretical predictions are correct. This survey has been allocated a total of 560 hours of time on UKIRT to date, of which 110 hours have been used for a pilot study covering 1.5 square degrees in the COSMOS and UKIDSS/UDS fields. Further details (including the membership of the collaboration) can be
found here.
SCUBA2 Cosmology Legacy Survey
The SCUBA2 Cosmology Legacy Survey (S2CLS) is a collaboration of ~100
scientists in the UK, Canada and the Netherlands. The survey will
exploit the immense increase in mapping speed, fidelity and sensitivity
of the new SCUBA2
submillimeter camera on the James Clerk Maxwell
Telescope in Hawaii. The goal of the survey is to provide the first
large samples of extragalactic sources selected in the 450- and 850-um
wavebands. These atmospheric windows allow us to access the redshifted
far-infrared emission from luminous but highly, high-redshift galaxies
and AGN - pin-pointing an intense era of activity in the early Universe
associated with the formation of massive galaxies and black holes. The
survey has a simple two-tier design, comprising a wide 850-um component
and a deeper 450um survey over a smaller region. The 850-um
observations will deliver 10,000's of submillimetre galaxies, allowing
the first detailed statistical study of the submillimetre galaxy
population. At the same time the survey will have the area coverage
needed to search for rare sub-classes of submillimetre galaxies
(e.g. transition objects) which may provide powerful insights into the
processes operating within these systems, such as starburst- and
AGN-powered feedback, and trace overdensities of submillimetre sources
which may pin-point the initial collapse of proto-clusters. The very
deep 450-um observations will enable us to resolve for the first time
the bulk of the extragalactic background light at 450um, as well as
providing precise positions sufficient to directly identify the
counterparts to these sources in other wavebands and assess the size of
the submillimetre-emitting regions. This single co-ordinated survey
programme will revolutionize our understanding of submillimetre
galaxies, and indeed galaxy formation in general, with enormous and
lasting legacy value, as well as providing a springboard for future
exploitation of Atacama Millimeter Array (ALMA), Herschel, LOFAR, James
Webb Space Telescope (JWST) and the Square Kilometer Array (SKA).
Further details can be
found here.
Past Projects: SCUBA and Star-formation in Distant Galaxies
This project is a collaboration
between myself, Rob Ivison,
Andrew Blain and Jean-Paul
Kneib. We used SCUBA,
the new sub-mm bolometer array on the 15-m JCMT on Mauna Kea
to make the first sub-mm maps of the distant Universe. These have been
used to study the star-formation properties of distant galaxies seen
through the cores of rich clusters. These galaxies are seen in the
sub-mm because the dust within them is reprocessing UV and optical
star-light and emitting large quantities of radiation in the sub-mm.
Thus sub-mm maps allow us to estimate the typical star-formation rate
in the distant Universe and hence search for the epoch of galaxy
formation. The first observations for this were taken in the late
summer of 1997 and the results from those are discussed in this paper. The final
survey covered a total area of 0.01 sq. degrees and we published
papers on the brightest source in our
sample, the constraints on the star-formation history of the Universe
from our sub-mm counts
(see also here), the
implications of our counts for observations with the next generation of
sub-mm and CMB experiments (here), and
the optical morphologies and colors of the faint sub-mm population
using HST data. Further papers
in this series deal with the sub-mm
counts from our complete survey, the detection in CO of the brightest sub-mm galaxy we have
identified, the sub-mm emission from central cluster galaxies, the redshift
distribution of galaxies selected in the sub-mm (from the optical and radio) and the discovery of
extremely red counterparts to a modest number of sub-mm sources.
A complete list of the publications arising from this project is given
on this page.
Past Projects: Lensing and the Nature of Distant Galaxies
These projects rely on the dependence of the shear induced
in all background galaxies seen through a rich cluster on both
the mass in the lensing cluster and the galaxy's distance. Using deep
HST imaging we can construct a detailed model of the mass distribution
within the cluster and hence use this to predict the redshifts of large samples of
background field galaxies. The method is purely geometrical and only
requires that we can measure the shape of the distant galaxy, it thus
can be successfully applied to galaxies > 10× fainter than
conventional techniques. We have already applied this technique to the
rich cluster A2218 and confirmed our predicted redshifts using
spectroscopic observations of the brighter arclets. Jean-Paul
Kneib, Harald Ebeling, Graham Smith and I are
expanding this analysis with Cycle 8 time to a provide the first
statistically reliable sample of around a dozen luminous X-ray clusters
at z~0.2 all imaged with WFPC2 (based on the Magic-24 sample).
In addition to the HST observations, this sample is also being observed in
the X-ray with XMM and imaged in the optical over 0.5 degree fields
with the CFH12k camera on CFHT. We have also scheduled
time on LRIS/Keck-I and LDSS2/WHT to obtain spectroscopic observations
of the brighter lensed features and the cluster galaxies. These
will be used to compare and contrast the properties of these
clusters and their galaxy populations with those
of the substantially lower-richness
clusters also being studied with HST by the group in Durham.
Past Projects: The Evolution of Galaxies as a Function of Environment
The first part of this program relates to
the fundamental plane of galaxies at z=0.2. This is a Durham-based
project with Richard Bower
and Michael Balogh. We've upgraded the capabilities of the LDSS-2
spectrograph on the 4.2-m WHT, La Palma (now moved to
the Magellan 6.5-m in Chile), to enable us to use it to
obtain intermediate resolution spectroscopy of large samples of
galaxies in z~0.2 clusters. The next observing run for this program was in October
1998 and used the charge-shuffling mode of the
newly refurbished LDSS++ on the 3.9-m AAT to observe
a small sample of galaxies in a cluster at z=0.31. We hope to expand
these observations to compile a sample of galaxies at z=0.3 similar
to our z~0.2 catalog.The second aspect of this program is a similarly detailed study of galaxies in low-density environments at z~0.2 using X-ray selected poor clusters and groups. The core science is based on a sample of nine clusters for which deep imaging with HST obtained during Cycle 8. This compliments the second phase of the MORPHS project which is also using HST to look at the properties of galaxies in the low-density outskirts of very rich clusters. We hope to use the variation of galaxy properties, both star-forming and passive, between the low-density groups and the higher-density clusters to search for the physical mechanisms responsible for the rapid evolution of the galaxy populations within clusters. An extension of this project to a sample at z=0.5 is underway.
Past Projects: MORPHS
This project aimed at understanding
the evolution of galaxies in high density environments (rich clusters)
over the last 5-8 Gyrs. We combine deep Hubble Space Telescope WFPC2 pointings
of the clusters to determine galaxy morphology with multi-object
spectroscopy of the same galaxies taken with the 5.1-m Hale, 4.2-m WHT,
3.9-m AAT and 3.6-m NTT telescopes. A spectroscopic catalog of
roughly 700 galaxies in the 10 clusters is also available. The
project has now moved to its second phase where we are extending our
study into the outskirts of the clusters to tie the evolution in the
cluster and field populations together. We are also using narrow-band
imaging to investigate the distribution of emission-line galaxies
within the clusters, medium resolution spectroscopy of the
early-type galaxies to search for traces of past star-formation and deep
radio maps to uncover evidence for dusty starburst galaxies. The main
collaborators involved in this work are: Warrick
Couch, Alan
Dressler, Richard
Ellis, Gus
Oemler, Bianca Poggianti and myself. The complete catalogs of objects detected in
our WFPC2 images, as well as information on the morphologies of a
brighter subset are available from here,
while the spectral catalog for these clusters is on this page Images of a few of the clusters are shown
here. A number of the
papers produced by this group are already published.
Past Projects: CIRCuS and the LCO/2dF Rich Cluster Study
Moving to even lower redshifts,
this is a long term project to study a statistically reliable sample of
the richest clusters in the southern hemisphere in a redshift slice
between z=0.07-0.15. The project has completed wide-field
(2×2 degree) B and R imaging from the 40" telescope at Las Campanas Observatory
(Chile) of over 20 clusters, totalling over 70 square degrees of sky.
These images are being used to select galaxies for subsequent
spectroscopic follow-up with the 400-fibre 2dF multi-object spectrograph on
the 3.9m AAT in Australia. Our aim is to obtain spectra for roughly
20,000 galaxies in the 20 clusters providing an unprecedented view of
the dynamics of rich clusters and their galaxy populations. Our first
allocation of 2dF time was in May 1998 and we obtained high-quality
spectroscopy of 2,000 galaxies in three of our clusters. The
collaborators in this program are Warrick
Couch, Alastair Edge, Eileen O'Hely,
Kevin Pimbblet,
Ann Zabludoff and me. A true color image of the central regions of
one of our clusters is shown here.
Past Projects: Bits-n-Bobs
A few spin-off projects (some using data taken for other purposes by other people and some using data taken by other people for the same purpose). To save trees my to-do list is here.``A Catalogue of Morphologies for Dwarf Galaxies in the Coma Cluster'', Smail, I., Lucey, J.R., Davies, R.L., de Jong, R., Smith, R.J., 20xx, in imagination.
And I hope you've noticed that I'm quite definitely not doing anything on intra-cluster light... although I can advise on this topic.
Ian Smail, Ian.Smail [at] durham.ac.uk