A programme of Astrophysics, Cosmology and Technology in Cardiff 2013-2016

Lead Research Organisation: Cardiff University
Department Name: School of Physics and Astronomy

Abstract

We propose a programme of Astrophysics, Cosmology and Technology development for Astrophysics and Cosmology, to investigate star and planet formation in our own and other galaxies, how galaxies form and evolve, and how the Universe we see around us today originated in the big bang. We will use our world-leading position in exploitation of the Herschel satellite galactic and extragalactic surveys, along with complemeantary observations with other facilities and theoretical modelling. We will also develop new sophisticated yet robust statistical methods for exploiting the large datasets emerging from the Planck satellite and other large cosmological surveys. We will continue to develop the world's most sensitive detectors for very long infrared wavelengths, along with associated optical components utilising 'metamaterials' the class of materials designed and manufactured by human beings to have the properties best suited to their task, rather than relying on naturally occurring minerals and plastics. Both of these areas of technology development have potential wide applications outside of Astronomy, in areas such as security scanners and bio-medical imaging for example. The technologies used for imaging can also be extended to undertake spectroscopy, and we propose a programme to develop the capability to obtain a spectrum of every point in a large area image of the sky, which is essential for understanding how far away the objects found in deep surveys are, but also what the conditions in the gas that make up these objects are.

Planned Impact

The technology programme proposed here will have extensive impact outside of astronomy. Firstly in other academic subject areas such as Earth-observing where the technology is used to look downwards or sideways through the atmosphere rather than upwards, but also in bio-medical imaging, where the Far-infrared wavelength range has many spectral features, and is currently being used in collaboration with the School of Optometry in Cardiff to assess corneal damage, for example. Secondly we also plan to exploit the technology commercially, through the spinout company QMCI (www.terahertz.co.uk) which operates from within the School, with broad applications from fast plasma diagnostic systems in use in Fusion experiments, through laboratory spectroscopy across a wide range of chemistry and materials applications, through to security imaging. We also plan a very strong Outreach programme across both the technology developments and the observational and theoretical astrophysics and cosmology programme, following on from the skills developed during the very successful Herschel/Planck outreach programme, with web-based and standard media information releases, but also tied in with Open days, school visits, and going out into schools and colleges to give presentations and host workshops. This work is closely aligned also with the in-house science communication company Science Made Simple.

Publications

10 25 50
 
Description (a) Extragalactic
We used the most comprehensive study of high redshift sub millimetre galaxies (Rowlands et al 2014) to study dust origins and evolution at redshifts 2-6. We first show that dust produced only by low-intermediate-mass stars falls a factor 240 short of the observed dust masses of SMGs. We then find that unlike suggested in the literature, that the amount of dust production in early galaxies does not depend on the star formation history assumed.

In Mattsson et al (2014) we argue that our nearest neighbour M31 helps build a case for cosmic dust in galaxies being the result of substantial interstellar grain growth, while the net dust production from stars may in fact be rather small. We provide the tightest constraints on dust sources in galaxies thanks to the exquisite resolution from Herschel.

We demonstrated the first unambiguous detection of a massive dust reservoir (including the first detection of a noble gas compound) in the Crab Nebula in ApJ & Science (Gomez et al 2012, Barlow et al 2013) and discovered that dust does not form in Type Ia explosions (Gomez et al 2012). Our Herschel results finding large quantities of dust in supernovae was listed as one of the highlights of the mission in Nature (2013:495:151); this refers mostly to our work, and demonstrates its impact. This also led to a News & Views feature by Gomez (Gomez et al 2014).

Herschel's ability to detect dust at all temperatures revealed a surprising population of gas- and dust-rich galaxies with blue stellar populations (Clark et al 2015). These galaxies (the first local sample selected on the basis of dust mass) contain a significant fraction of dust in the local universe, but only a tiny fraction of the stars. They have unusually low molecular gas fractions ( H2/HI~20%), comparing the predicted HI with measured (unresolved) masses from the literature suggests ratios of only 1-8% and molecular-to-dust mass ratios of 5-15: an order of magnitude lower than observed in "normal" spirals. Their blue colours combined with cold dust temperatures (~15K) may also suggest a difference in the properties of the grains, since grains with higher dust emissivity would come into equilibrium with the stellar radiation field at lower temperatures.

(b) star-formation

(i) Statistical arguments suggesting that low-mass prestellar
cores spawn 4 or 5 stars with a high efficiency (i.e. a large
fraction of the core mass ends up in stars) -- rather than 1
or 2 with relatively low efficiency, as is commonly presumed.

(ii) Simulations of molecular clouds being blown apart by HII
regions, demonstrating that although star formation is
accelerated (relative to what would have happened without
the HII regions), there is actually less star formation, and the
typical stellar masses are lower.

(iii) Procedures for converting the observed properties of an
ensemble of prestellar cores into the distributions regulating
their intrinsic 3D density and velocity fields -- a very thorny
inverse problem.

(iv) Simulations of core collapse and fragmentation showing
that the low-mass end of the IMF requires that their intrinsic
turbulence have a large solenoidal component, and that
radiative feedback be episodic.

(v) New parametrisation of the IMF.

(vi) Semi-analytic theory of the origin of the column-density
PDF in a star-forming cloud.

(vii) Demonstration that -- contrary to the accepted wisdom
-- the majority of Sun-like stars is not single.

(viii) Simulations and semi-analytic theory of the global
collapse and local fragmentation of filaments, showing that
fragmentation is likely to occur while the filament is still
assembling, that the dispersion relation giving the most
likely spacing is significantly different from that normally
used (which assumes that the filament is already assembled); and that the spacing gives an estimate of the time for which the core has been assembling.

(ix) Simulations of cloud/cloud collisions indicating that
slow collisions result in the formation of a hub-and-spoke
system of filaments and thereby a single concentrated massive cluster with a broad mass function and a few very massive stars; whereas fast collisions result in the formation of a spiders web of filaments and thereby a distributed ensemble of sub-clusters with a narrower mass function and no very massive stars.

(x) Simulations of the formation of bipolar HII regions
following cloud/cloud collisions.

(xi) The PPMAP algorithm, which allows the user to
extract much more information than standard
procedures from multi-wavelength observations of dust
continuum emission (from Herschel and/or other instruments) -- specifically, integrated AND temperature-differential column-density maps, hence better estimates of mass. This in turn allows the user to dig out very low-luminosity, otherwise invisible, sources embedded in molecular clouds.

(xii) An analytic paper deriving a temperature-independent column-density threshold for star formation which predicts rather accurately the characteristic scales in star formation, in particular the mass at the peak of the IMF.

(c) Detectors
The Cardiff kinetic Inductance group is now considered one of the world leaders in this field and as a result has led to many fruitful collaborations with international partners. During our previous program of research we have made many advances as well as improving capability within the UK in this field. Key Achievements during the last consolidated grant period include:
1)The first measurement of generation-recombination noise in Aluminium LEKID devices,
2)Measurements of the electron phonon relaxation time in TiN superconducting films,
3)Demonstration of a strained silicon cold electron bolometer using Schottky contacts,
4) Demonstration of the effects of anomalous response and power dependence on the effective optical efficiency of LEKIDs fabricated from TiN,
5) Developed a microwave theory to explain and mitigate cross-coupling between superconducting resonators.,
5) Successful demonstration of an on-chip spectrometer,
6) Demonstrated the feasibility of a Horn coupled LEKID based instrument suitable for high background and commercial application.,
7)Developed a full 350 GHz wide field of view Kinetic Inductance camera capable of imaging terrestrial objects.,
8) Measured the optical performance of ultra-sensitive TES detectors,
9) Assisted in the development and testing of the mm wave detectors for NIKA and NIKA,
10) Measured the photon noise and spectral response of a Hilbert Fractal based LEKID.
Exploitation Route The Herschel data is a huge legacy for the astronomical communities across the world.

The technologies developed under this grant are already being used in other astronomical experiments both ground based and in space, as well as in other applications such as laboratory spectroscopy, fusion plasma diagnostics, security screening.

The outreach programme based around Herschel in particular has had significnat impact, e.g. being used in the BBC "Stargazing Live" programmes as well as by ESA in their publicity material, reaching millions of people and inspriing young people to work in science.
Sectors Aerospace, Defence and Marine,Energy,Culture, Heritage, Museums and Collections,Security and Diplomacy

 
Description The Herschel science results have been used exensively by our own outreach proigramme, but also very extensively by ESA in their own publicity material, including being included on the BBC Stargazing LIve programme wiht over 2 million viewers and on and Sky at NIght. The THz optics components and superconducting detectors have been utlised in current and upcoming ground and space based instruments for astronomy and Earth Observing. But also other applications including laboratory spectroscopy, fusion plasma diagnostics, and passive imaging including security scanning. The commercial applications usually through the co-located spinout company QMCI. Establishment of the new spin out company Sequestim is based on research developed on this award.
First Year Of Impact 2017
Sector Aerospace, Defence and Marine,Energy,Culture, Heritage, Museums and Collections,Security and Diplomacy
Impact Types Cultural,Economic

 
Description ERC Consolidator Grant
Amount € 1,800,000 (EUR)
Organisation European Research Council (ERC) 
Sector Public
Country Belgium
Start 09/2015 
End 09/2020
 
Title Chemev model 
Description Openly available code for calculating chemical evolution of galaxies 
Type Of Material Improvements to research infrastructure 
Year Produced 2016 
Provided To Others? Yes  
Impact NA - too soon 
URL https://github.com/zemogle/chemevol
 
Title Herschel ATLAS database 
Description The Herschel ATLAS was the largest (in area) extragalactic survey carried out with the Herschel Space Observatory. As a result of STFC support, we have now released all the images and catalogues of submm and optical sources obtained with this survey. The survey covered 660 square degrees and detected ~500,000 sources. 
Type Of Material Database/Collection of data 
Year Produced 2016 
Provided To Others? Yes  
Impact It is being used by the worldwide astronomical community and is unlikely to be superceded as a fundamental catalogue of the submm universe for at least 20 years. 
URL http://www.h-atlas.org
 
Company Name QMC Instruments Ltd 
Description QMC Instruments Ltd develops instrumentation for the detection and processing of electromagnetic radiation at wavelengths ranging from microwaves to the near infrared. Products include a long-established range of cryogenic detectors and associated components and instruments.   The development of this technology comes from the activity of the Cardiff University Astronomy Instrumentation Group, funded through successive STFC consolidated/rolling grants. 
Impact QMCI products are used in diverse applications such as atmospheric remote sensing, astronomy, semiconductor materials characterisation, hot plasma fusion diagnostics and electron spin resonance (ESR) spectroscopy. This has societal as well as economic benefit to the UK.
Website http://www.terahertz.co.uk/qmc-instruments-ltd
 
Description Research Network 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Invited talk for EPSRC Teranet meeting. Discussion of status and activities in UK THz community.
Year(s) Of Engagement Activity 2017
URL http://gtr.rcuk.ac.uk/projects?ref=EP/M00306X/1