The Evolution of Mass and Light

Lead Research Organisation: University of Nottingham
Department Name: Sch of Physics & Astronomy

Abstract

The fellowship programme is centred upon the Herschel Satellite's two largest imaging surveys. Using these, the programme will investigate two fundamental but poorly understood aspects of galaxy evolution. Herschel operates in an unexplored region of the electromagnetic spectrum (0.1-0.5 mm) where an incredible 50% of the Universe's radiation is emitted. The sources that dominate at these wavelengths are young dust enshrouded star forming galaxies that typically evade detection in the optical. A tantalisingly small fraction of these galaxies have been seen at other wavelengths from the ground comprising only a very bright distant subset. These rare galaxies are merely the tip of the iceberg, not representative of the whole population. Frustratingly, little is known about the evolution of these distant systems and their relationship with local galaxies because the underlying population bridging the huge void has not been detected. This is a vital missing piece of the galaxy formation puzzle that has proven a significant obstacle. Herschel is satisfying a long awaited demand for a sensitive, high resolution facility to rapidly survey the sky in the sub-millimetre and finally detect a significant proportion of this elusive population.

The first part of the programme exploits the fact that the sub-millimetre is extraordinarily well suited to detecting gravitational lenses. The Herschel survey data will contain around 500 new strong lens systems out to a distance looking back over two thirds of the Universe's age. The first milestone is to identify and characterise galaxies acting as lenses to produce the largest and most distant sample to date. Secondly, applying a powerful reconstruction technique developed by the author to the lenses to measure mass profiles, the morphology of the baryons and the dark matter will be measured (in some cases separately) to investigate their evolution over the last 70% of the Universe's history. This is an exceptional opportunity to constrain models of structure formation in a way that has not been feasible until now.

Lensing also magnifies the flux of background objects above the detection threshold. Therefore, in addition to studying the evolution of the lenses themselves, the sample will be used to probe the population of dusty sources fainter than the survey sensitivity. Furthermore, using the aforementioned reconstruction technique, highly magnified undistorted surface brightness maps of each source will be computed to analyse in detail the morphology of the faint (and therefore generally more distant) dusty sources. Finally, the lens sample will place the most restrictive lensing limits on the cosmological model to date in a way that is complementary to other methods.

The second part of the fellowship programme will apply a new method for optimally measuring the evolution in luminosity of the hundreds of thousands of new Herschel sources detected. This will be combined with the framework established over several years by the author to finally provide a definitive study of the link between local systems and the dusty star forming galaxies that prevailed when the Universe was only 40% of its current age. Specifically, this involves measuring the growth of stellar mass and evolution of star formation in sub-millimetre galaxies (using another new method developed for reconstructing star formation histories) and measuring their transformation into other galaxy types as they evolve.

In terms of scale and viability of the programme, the Herschel data account for an impressive 1500 hours of observations over 700 square degrees of sky. This reflects a large investment from the UK astronomical community and one which must be justified by maximising scientific exploitation and impact.

Publications


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Agius N (2015) H-ATLAS/GAMA and HeViCS - dusty early-type galaxies in different environments in Monthly Notices of the Royal Astronomical Society
Bourne N. (2016) The Herschel-ATLAS Data Release 1 - II. Multi-wavelength counterparts to submillimetre sources in Monthly Notices of the Royal Astronomical Society
Clark C (2015) Herschel-ATLAS: the surprising diversity of dust-selected galaxies in the local submillimetre Universe in Monthly Notices of the Royal Astronomical Society
De Geyter G (2015) Dust energy balance study of two edge-on spiral galaxies in the Herschel-ATLAS survey in Monthly Notices of the Royal Astronomical Society
Eales S (2015) H-ATLAS/GAMA: quantifying the morphological evolution of the galaxy population using cosmic calorimetry in Monthly Notices of the Royal Astronomical Society
Fuller C. (2016) H-ATLAS: the far-infrared properties of galaxies in and around the Coma cluster in Monthly Notices of the Royal Astronomical Society
 
Description We have developed a new technique that works in Fourier space for reconstructing images of a gravitationally lensed source. This is aimed specifically at the analysis of data produced by the new ALMA interferometric array. This method has now been applied successfully to a new sample of strong gravitational lenses imaged with ALMA. The results are in the process of being published and shed new light on the star formation processes in galaxies in the early universe.
Exploitation Route Publication of our method will allow other users to adopt the same approach. Many groups around the world are now using this method.
Sectors Other
 
Description The lensed image reconstruction algorithm used in the fellowship turns out to be immediately applicable to the reconstruction of MRI images. This has therefore motivated collaboration with the MRI group here at the University of Nottingham to better explore potential gains in MRI imaging. This work is ongoing.
First Year Of Impact 2015
Sector Healthcare
Impact Types Societal
 
Title Herschel ATLAS 1st data release 
Description This is the data release made by the Herschel ATLAS consotium. The data have undergone extensive processing, testing, and characterisation. The specific contribution to this dataset made in this award is the assignment of optical counterparts to the sub-millimetre sources detected in the H-ATLAS survey 1st data release. 
Type Of Material Database/Collection of data 
Year Produced 2016 
Provided To Others? Yes  
Impact This is a large and unique dataset which has been made publically available. The legacy value of the dataset is very high and as such it will be used in many different areas of astronomy. 
URL http://www.h-atlas.org
 
Description Herschel ATLAS - Cardiff 
Organisation Cardiff University
Department School of Physics and Astronomy
Country United Kingdom of Great Britain & Northern Ireland (UK) 
Sector Academic/University 
PI Contribution Scientific Research Collaboration
Collaborator Contribution Scientific Research Collaboration
Impact Scientific Research Collaboration
Start Year 2009
 
Description LSST Dark Energy Science Collaboration 
Organisation Stanford University
Country United States of America 
Sector Academic/University 
PI Contribution This is a new collaboration. I have been granted 'LSST Affiliate PI status' for three years until 2020, coinciding with the end of this fellowship. The collaboration has been initiated on the understanding that I will bring new techniques to solve the problem of finding strong gravitational lens systems in the vast image data that the new LSST telescope will produce. I also plan to help work towards an automated pipeline for modelling these new systems, to vastly increase our knowledge of galaxy structure, dark matter content in galaxies and how these evolve as the Universe ages.
Collaborator Contribution This is a collaboration involving hundreds of partners spread across the world. The LSST is a new telescope which will produce optical imaging of large areas of the sky. The images will be analysed by many different 'science collaborations' with many different aims, each falling under the umbrella of the LSST consortium.
Impact None yet - collaboration has just started.
Start Year 2017
 
Description LSST Dark Energy Science Collaboration 
Organisation University of Oxford
Country United Kingdom of Great Britain & Northern Ireland (UK) 
Sector Academic/University 
PI Contribution This is a new collaboration. I have been granted 'LSST Affiliate PI status' for three years until 2020, coinciding with the end of this fellowship. The collaboration has been initiated on the understanding that I will bring new techniques to solve the problem of finding strong gravitational lens systems in the vast image data that the new LSST telescope will produce. I also plan to help work towards an automated pipeline for modelling these new systems, to vastly increase our knowledge of galaxy structure, dark matter content in galaxies and how these evolve as the Universe ages.
Collaborator Contribution This is a collaboration involving hundreds of partners spread across the world. The LSST is a new telescope which will produce optical imaging of large areas of the sky. The images will be analysed by many different 'science collaborations' with many different aims, each falling under the umbrella of the LSST consortium.
Impact None yet - collaboration has just started.
Start Year 2017
 
Description UKIRT Hemisphere Survey 
Organisation Royal Observatory Edinburgh
Country United Kingdom of Great Britain & Northern Ireland (UK) 
Sector Public 
PI Contribution I am the project scientist.
Collaborator Contribution Data reduction, data processing, online archiving, data quality control.
Impact Data release expected mid 2016.
Start Year 2006
 
Description UKIRT Hemisphere Survey 
Organisation University of Arizona
Department Space - Department of Physics
Country United States of America 
Sector Academic/University 
PI Contribution I am the project scientist.
Collaborator Contribution Data reduction, data processing, online archiving, data quality control.
Impact Data release expected mid 2016.
Start Year 2006
 
Description UKIRT Hemisphere Survey 
Organisation University of Cambridge
Department Institute of Astronomy
Country United Kingdom of Great Britain & Northern Ireland (UK) 
Sector Academic/University 
PI Contribution I am the project scientist.
Collaborator Contribution Data reduction, data processing, online archiving, data quality control.
Impact Data release expected mid 2016.
Start Year 2006
 
Description UKIRT Hemisphere Survey 
Organisation University of Hawaii
Department Institute for Astronomy
Country United States of America 
Sector Academic/University 
PI Contribution I am the project scientist.
Collaborator Contribution Data reduction, data processing, online archiving, data quality control.
Impact Data release expected mid 2016.
Start Year 2006
 
Description UKIRT Hemisphere Survey 
Organisation University of Hertfordshire
Department School of Physics and Astronomy
Country United Kingdom of Great Britain & Northern Ireland (UK) 
Sector Academic/University 
PI Contribution I am the project scientist.
Collaborator Contribution Data reduction, data processing, online archiving, data quality control.
Impact Data release expected mid 2016.
Start Year 2006
 
Title Adaptive semi-linear inversion 
Description This is a new algorithm, now published, which is used to reconstructed the gravitationally lensed image of a background source. The agorithm supercedes older methodolgies which have associated problems and biases. 
Type Of Technology New/Improved Technique/Technology 
Year Produced 2015 
Impact We are aware that several research groups around the world have adopted our new algorithm. 
 
Description Astronomical society talks 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Type Of Presentation Keynote/Invited Speaker
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Multiple talks to Astronomical and other Scientific Societies


Public Engagement
Year(s) Of Engagement Activity 2010,2011,2012,2013,2014
 
Description Public talks 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact This entry represents multiple talks given to the general public on astronomical themes. These include events held during university open days, specific outreach events like 'Pint of Science' and 'Skeptics in the pub' and the Nottingham public lecture series.
Year(s) Of Engagement Activity 2014,2015,2016
 
Description School visits 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact This single entry represents several tens of duplicated events across local schools in the Nottingham region. Events usually entail giving a powerpoint presentation.


Inspiring the younger generation of potential scientists
Year(s) Of Engagement Activity 2011,2012,2013,2014,2015