DESpec: Spectroscopic upgrade of the Dark Energy Survey

Lead Research Organisation: University of Portsmouth
Department Name: Institute of Cosmology and Gravitation


ark Energy is one of the biggest mysteries in the whole of science. Observations over the past decade strongly favour a 'concordance' model in which the Universe is flat and contains approximately 4% ordinary atomic matter, 21% Cold Dark Matter and 75% Dark Energy. The Dark Energy paradigm and its extensions pose fundamental questions about the origins of the Universe: is Dark Energy an actual ingredient, or should Einstein's gravity theory be modified?

We propose a new initiative, the Dark Energy Spectrometer (DESpec), a 4000-fibre instrument for the Blanco 4-meter telescope in Chile that would take advantage of the infrastructure recently built for the Dark Energy Camera to achieve excellent science at low cost Starting in 2017, when the Dark Energy Survey (DES) is completed, DESpec would obtain spectroscopic redshifts for ~10 million galaxies from DES+VISTA Hemisphere Survey (VHS) and thereby improve our measurement of Dark Energy. DESpec will also constrain neutrino masses, enable new techniques such as redshift-space distortions to constrain Dark Energy vs. Modified Gravity models, and enable powerful studies of galaxy evolution. UK involvement would allow for the design to be harmonized with the needs and leadership roles of the UK astronomy community. As with DES, the UK investment would be highly leveraged by partnership with the US and other foreign partners. The total DESpec instrument cost is estimated at $40M, similar to DECam. The request funding covers both instrumentation and and preparations for target selection and survey strategy. The work described below is fully coordinated with the work for BigBOSS:UK, another proposed spectroscopic instrument.

Planned Impact

The DESpec project will develop the skills of Post-docs and technical staff.

In particular, the work on simulations for target selection and survey strategy will be of use not only for DESpec, but also for a number of other planned spectroscopic surveys.

The Opto-Mechanical design and specification of the fibre imaging system will have broad implications for optical systems.


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Bolejko K (2013) Antilensing: the bright side of voids. in Physical review letters
Description Research at the ICG has helped understand the formation and evolution of the universe. This information is important to advance our understand of fundamental physics as well as being of great interest and fascination by the general public. In this grant, we explore the development of a new instrument, which was later merged with another design and recently selected by STFC for construction
Exploitation Route This work has directly lead to the selection of the Dark Energy Spectroscopic Instrument (DESI) by STFC for funding and construction in collaboration with US partners (DoE). This study helped secure UK leadership and involvement in key areas of the instrument design and science exploitation. UK are now leading two of the main components
Sectors Education,Manufacturing, including Industrial Biotechology
Description Research at the ICG has helped understand the formation and evolution of the universe. This information is important to advance our understand of fundamental physics as well as being of great interest and fascination by the general public.
First Year Of Impact 2014
Sector Education,Culture, Heritage, Museums and Collections
Impact Types Cultural,Societal
Description DES 
Organisation Dark Energy Survey (DES)
Country Global 
Sector Charity/Non Profit 
PI Contribution Scientific leadership and guidance, preparation of scientific simulations and preparations, organisation of meetings and events
Collaborator Contribution Access to proprietary data and scientific collaboration
Impact Scientific publications (see publication list)
Start Year 2006
Description DESI 
Organisation Lawrence Livermore National Laboratory
Country United States of America 
Sector Public 
PI Contribution The ICG (especially Will Percival) have been leading a UK team to work with the Dark Energy Spectroscopic Instrument (DESI) which is a merger of two previous projects, namely DESpec and BigBOSS.
Collaborator Contribution The UK team are helping with science design and exploitation, technical work on the fiber optics (durham) and optical corrector (UCL)
Impact DESI recently received STFC funding for the UK team to participate in the construction and running of this instrument
Start Year 2012
Description Stargazing at Portsmouth Historic Dockyard 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? Yes
Type Of Presentation Workshop Facilitator
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact 450 people attended a Stargazing Live partner event at Portsmouth Historic Dockyard, organised by the ICG. There were a variety of activities linked to our research and the opportunity for members of the public to ask our researchers questions which sparked discussion

Many members of the public who attended the event were not previously aware of the ICG or that cosmology research was being carried out in their home city.
Year(s) Of Engagement Activity 2013