Extragalactic Astrophysics and Cosmology at Imperial College London
Lead Research Organisation:
Imperial College London
Department Name: Physics
Abstract
Our work in the Astrophysics Group at Imperial College London, in the broadest terms, is aimed at improving our understanding of the evolution of the Universe. The basic framework is the Big Bang model, the picture that the Universe began in a hot violent explosion several billion years ago. As the Universe expands it cools, and under the force of gravity matter segregates and condenses to form galaxies composed of stars. Our current picture of the Universe has changed dramatically in recent decades, both observationally and theoretically. The most important observational improvement has been the development of telescopes that map the sky over the complete range of wavelengths, both shorter than visual - gamma-ray, X-ray, ultraviolet - and longer than visual - infrared, microwave, radio. Two surprising results have emerged from these observations. First, there must be much more matter, dark matter, in the Universe than we can see, to explain the strong gravitational pull of galaxies. Second, the expansion of the Universe is accelerating, which we can only understand if empty space (the vacuum, nothing) possesses energy, dark energy. The aim of our work at Imperial College London, then, is to undertake observations and theoretical studies to develop this picture of the evolution of the Universe in more detail. We can order our research by wavelength, starting with X-rays. The shorter the wavelength of light, the higher the energy of photons, so X-rays can be used to study the most energetic processes in galaxies, particularly the accretion of matter onto black holes, and we are using the XMM-Newton satellite to explore these extreme environments. There is a very massive black hole, over a million times the mass of the Sun, at the centre of most galaxies, and a recent discovery has been that the mass of the black hole is proportional to the mass of the galaxy in which it lies. Our work using the Chandra satellite is aimed at understanding why this is and the implications for how galaxies form. At near-infrared wavelengths we are taking advantage of a new generation of large detectors to make a deep map of the sky, and are using this survey to search for distant quasars. The expansion of the Universe stretches (redshifts) the light from far away sources, so the most distant sources are the most redshifted. Light from the furthest quasars, from the time when they were first forming, is stretched to the near-infrared. By discovering the first quasars we can analyse their light to tell us about the conditions at that time, when the Universe was only 5% of its present age. Although stars emit most of their light near optical wavelengths, an important development in the 1980s and 1990s was the discovery that much of this light is hidden by the smoke from burning stars ('dust' to astronomers). The light is absorbed by dust and re-emitted at far-infrared wavelengths. About half of all starlight emerges at far-infrared wavelengths, so we need to study galaxies at these wavelengths to make a complete census of where and when the stars we see today formed. To this end over the next few years we will be analysing far-infrared maps made with the Herschel satellite, due to be launched in 2008. Finally, at microwave wavelengths we can see the furthest back in time, to the point when the Universe was so hot that matter was in the form of a plasma. In effect the entire sky looks like the surface of the sun, but that light has been redshifted by a factor of 1000, and stretched to microwave wavelengths. Analysis of the subtle variations in temperature of the microwave sky can provide a measurement of the amount of dark matter and dark energy. The launch of the Planck satellite in 2008 will provide the most detailed maps yet of the microwave sky. We will analyse the structure in these maps to obtain the most accurate measure of these cosmological parameters.
Publications
Mortlock D
(2009)
Discovery of a redshift 6.13 quasar in the UKIRT infrared deep sky survey
in Astronomy & Astrophysics
Smart R
(2010)
The distance to the cool T9 brown dwarf ULAS J003402.77-005206.7
in Astronomy and Astrophysics
Tauber J
(2010)
Planck pre-launch status: The optical system
in Astronomy and Astrophysics
Patel M
(2010)
The reanalysis of spectra of GRB 080913 to estimate the neutral fraction of the IGM at a redshift of 6.7
in Astronomy and Astrophysics
Wu J. H. P.
(2007)
Maxipol: Data analysis and results
in ASTROPHYSICAL JOURNAL
Johnson B. R.
(2007)
Maxipol: Cosmic microwave background polarimetry using a rotating half-wave plate
in ASTROPHYSICAL JOURNAL
De Troia G.
(2007)
Searching for non-Gaussian signals in the BOOMERANG 2003 CMB maps
in ASTROPHYSICAL JOURNAL
Clements D
(2017)
An introduction to the Planck mission
in Contemporary Physics
Clements D
(2017)
Cosmic sculpture: a new way to visualise the cosmic microwave background
in European Journal of Physics
Zotti G
(2018)
Exploring cosmic origins with CORE: Extragalactic sources in cosmic microwave background maps
in Journal of Cosmology and Astroparticle Physics
André P
(2014)
PRISM (Polarized Radiation Imaging and Spectroscopy Mission): an extended white paper
in Journal of Cosmology and Astroparticle Physics
Juszkiewicz R
(2010)
Weakly nonlinear dynamics and the s 8 parameter
in Journal of Cosmology and Astroparticle Physics
Barron D
(2014)
The POLARBEAR Cosmic Microwave Background Polarization Experiment
in Journal of Low Temperature Physics
Marchetti L
(2015)
The HerMES submillimetre local and low-redshift luminosity functions
in Monthly Notices of the Royal Astronomical Society
Burningham B
(2010)
47 new T dwarfs from the UKIDSS Large Area Survey 47 T dwarfs
in Monthly Notices of the Royal Astronomical Society
Paykari P
(2013)
Sparsely sampling the sky: a Bayesian experimental design approach
in Monthly Notices of the Royal Astronomical Society
Greenslade J
(2020)
The nature of 500 micron risers I: SMA observations
in Monthly Notices of the Royal Astronomical Society
Hodgkin S
(2009)
The UKIRT wide field camera ZYJHK photometric system: calibration from 2MASS
in Monthly Notices of the Royal Astronomical Society
Mortlock D
(2009)
Photometric constraints on white dwarfs and the identification of extreme objects
in Monthly Notices of the Royal Astronomical Society
Greenslade J
(2018)
Candidate high-z protoclusters among the Planck compact sources, as revealed by Herschel-SPIRE
in Monthly Notices of the Royal Astronomical Society
Driver S
(2011)
Galaxy and Mass Assembly (GAMA): survey diagnostics and core data release GAMA
in Monthly Notices of the Royal Astronomical Society
Rowan-Robinson M
(2016)
The star formation rate density from z = 1 to 6
in Monthly Notices of the Royal Astronomical Society
Duivenvoorden S
(2019)
Have we seen all the galaxies that comprise the cosmic infrared background at 250 µm =? = 500 µm?
in Monthly Notices of the Royal Astronomical Society
Clements D
(2018)
HERUS: the far-IR/submm spectral energy distributions of local ULIRGs and photometric atlas
in Monthly Notices of the Royal Astronomical Society
Watson L
(2011)
A Bayesian analysis of the 27 highest energy cosmic rays detected by the Pierre Auger Observatory The highest energy cosmic rays
in Monthly Notices of the Royal Astronomical Society
Clements D
(2016)
H-ATLAS: a candidate high redshift cluster/protocluster of star-forming galaxies
in Monthly Notices of the Royal Astronomical Society
Rowan-Robinson M
(2015)
Cold galaxies
in Monthly Notices of the Royal Astronomical Society
Asboth V
(2016)
HerMES: a search for high-redshift dusty galaxies in the HerMES Large Mode Survey - catalogue, number counts and early results
in Monthly Notices of the Royal Astronomical Society
Henrion M
(2011)
A Bayesian approach to star-galaxy classification Bayesian star-galaxy classification
in Monthly Notices of the Royal Astronomical Society
Bolton J
(2011)
How neutral is the intergalactic medium surrounding the redshift z = 7.085 quasar ULAS J1120+0641?
in Monthly Notices of the Royal Astronomical Society: Letters
Heavens A
(2013)
Combining size and shape in weak lensing
in Monthly Notices of the Royal Astronomical Society: Letters
Mortlock DJ
(2011)
A luminous quasar at a redshift of z = 7.085.
in Nature
Jaffe A
(2013)
Physics: The time lord and fellow travellers
in Nature
Bowyer J
(2011)
Improved method for detecting local discontinuities in CMB data by finite differencing
in Physical Review D
Feeney S
(2011)
First observational tests of eternal inflation: Analysis methods and WMAP 7-year results
in Physical Review D
Feeney SM
(2011)
First observational tests of eternal inflation.
in Physical review letters
Mattila S
(2018)
A dust-enshrouded tidal disruption event with a resolved radio jet in a galaxy merger.
in Science (New York, N.Y.)
Leggett S
(2009)
THE PHYSICAL PROPERTIES OF FOUR ~600 K T DWARFS
in The Astrophysical Journal
Oteo I
(2018)
An Extreme Protocluster of Luminous Dusty Starbursts in the Early Universe
in The Astrophysical Journal
Timmons N
(2016)
MULTI-WAVELENGTH LENS RECONSTRUCTION OF A PLANCK AND HERSCHEL-DETECTED STAR-BURSTING GALAXY
in The Astrophysical Journal
Leggett S
(2010)
MID-INFRARED PHOTOMETRY OF COLD BROWN DWARFS: DIVERSITY IN AGE, MASS, AND METALLICITY
in The Astrophysical Journal
Cantalupo C
(2010)
MADmap: A MASSIVELY PARALLEL MAXIMUM LIKELIHOOD COSMIC MICROWAVE BACKGROUND MAP-MAKER
in The Astrophysical Journal Supplement Series
{Ashdown}, M. And {Aumont}, J. And {Baccigalupi}, C. And {Banday}, A. And {Basak}, S. And {Bernard}, J.-P. And {Betoule}, M. And {Bouchet}, F. And {Castex}, G. And {Clements}, D. And {Da Silva}, A. And {De Zotti}, G. And {Delabrouille}, J. And {Dickinson}, C. And {Dodu}, F. And {Dolag}, K. And {Elsner}, F. And {Fauvet}, L. And {Fay}, G. And {Giardino}, G. And {Gonzalez-Nuevo}, J. And {le Jeune}, M. And {Leach}, S. And {Lesgourgues}, J. And {Liguori}, M. And {Macias}, J. And {Massardi}, M. And {
(2012)
PSM: Planck Sky Model
| Description | understanding of the Universe. computational tools |
| Sector | Education,Other |
| Impact Types | Cultural Societal |
| Description | Planck |
| Organisation | European Space Agency |
| Country | France |
| Sector | Public |
| PI Contribution | We are a data processing centre for the HFI Instrument on the Planck Satellite, responsible for determination of focal-plane and beam-shape parameter estimation. We also contribute heavily to various science products. |
| Collaborator Contribution | This is a huge EU project. |
| Impact | Lots of papers. Planck data products. |
| Description | Big Bang Fair |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | Yes |
| Type Of Presentation | Workshop Facilitator |
| Geographic Reach | International |
| Primary Audience | Schools |
| Results and Impact | It's an exhibition - does not match any of the types of presentation listed. It is aimed at all school ages and adults as well, but I'm not allowed to select such a mixture. Over 30000 attended this year |
| Year(s) Of Engagement Activity | 2009,2010,2012,2013 |
| Description | Planck 2011 |
| Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
| Part Of Official Scheme? | No |
| Type Of Presentation | Keynote/Invited Speaker |
| Geographic Reach | International |
| Primary Audience | Public/other audiences |
| Results and Impact | BBC World News channel segment N/A |
| Year(s) Of Engagement Activity | 2011 |
| Description | Royal Society Summer EXHIBITION |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | Yes |
| Type Of Presentation | Keynote/Invited Speaker |
| Geographic Reach | International |
| Primary Audience | Public/other audiences |
| Results and Impact | Audience type is *alll* of the above Resulted in media appearances. >10000 at actual show, >100000 accessed website. |
| Year(s) Of Engagement Activity | Pre-2006,2009,2012,2013 |