This book is about the Dark Energy Survey, a cosmological experiment designed to investigate the physical nature of dark energy by measuring its effect on the expansion history of the universe and on the growth of large-scale structure. The survey saw first light in 2012, after a decade of planning, and completed observations in 2019. The collaboration designed and built a 570-megapixel camera and installed it on the four-metre Blanco telescope at the Cerro Tololo Inter-American Observatory in the Chilean Andes. The survey data yielded a three-dimensional map of over 300 million galaxies and a catalogue of thousands of supernovae. Analysis of the early data has confirmed remarkably accurately the model of cold dark matter and a cosmological constant. The survey has also offered new insights into galaxies, supernovae, stellar evolution, solar system objects and the nature of gravitational wave events.
A project of this scale required the long-term commitment of hundreds of scientists from institutions all over the world. The chapters in the first three sections of the book were either written by these scientists or based on interviews with them. These chapters explain, for a non-specialist reader, the science analysis involved. They also describe how the project was conceived, and chronicle some of the many and diverse challenges involved in advancing our understanding of the universe. The final section is trans-disciplinary, including inputs from a philosopher, an anthropologist, visual artists and a poet. Scientific collaborations are human endeavours and the book aims to convey a sense of the wider context within which science comes about.
This book is addressed to scientists, decision makers, social scientists and engineers, as well as to anyone with an interest in contemporary cosmology and astrophysics.
Author(s): Ofer Lahav, Lucy Calder, Julian Mayers
Publisher: World Scientific Publishing
Year: 2020
Language: English
Pages: 444
City: London
Half Title Page
Title Page
Copyright Page
Contents
Foreword
Preface
Acknowledgements
Chapter -1: Introduction to the Dark Energy Survey Project and Science: What Have We Learned So Far?
−1.1 What is dark energy?
−1.2 The Dark Energy Survey
−1.3 The context of dark energy observations
−1.4 Four probes of dark energy
−1.5 DES joint galaxy clustering and weak lensing: Year 1 cosmology results
−1.6 DES-SN Year 3 cosmology results
−1.7 Non-dark energy results
−1.8 Josh Frieman and Ofer Lahav reflect on DES
References
Part I: Building the Dark Energy Survey
Chapter 1: Early Days of the Dark Energy Survey
1.1 Planning a future for the Blanco Telescope
1.2 An instrument partner for the Blanco
1.2.1 Think what we could do with a camera like that!
1.3 The Dark Energy Survey collaboration comes together, 2003 to 2004
1.3.1 Preliminary allocation of responsibilities
1.3.2 Visit to KPNO
1.3.3 Announcement of Opportunity
1.3.4 DES workshop at Fermilab
1.3.5 Presenting DES to the Program Advisory Committee
1.4 The NOAO proposal for DES
1.4.1 Temple review
1.4.2 Blanco Instrumentation Review Panel review
1.4.3 Memorandum of Understanding
1.5 Presenting DES to the scientific advisory committees
1.6 Building the DES collaboration
1.6.1 The United Kingdom joins the DES collaboration
1.6.2 Spain joins the DES collaboration
1.6.3 The wider DES collaboration
1.7 The DOE–NSF proposal for DES
1.8 Funding DES
Chapter 2: The Dark Energy Camera
2.1 DECam (Brenna Flaugher, Fermilab)
2.1.1 Rising from the ashes: 2003 to 2008
2.1.2 Staying afloat: 2008 to 2010
2.1.3 Wrapping it up: 2010 to 2012
2.2 The Optical Corrector (Peter Doel, UCL)
Reference
Chapter 3: Installation and First Light
3.1 Installation and First Light (Tim Abbott, Cerro Tololo Inter-American Observatory)
3.2 The path to First Light (H. Thomas Diehl, Fermilab)
3.2.1 Preparations off the Blanco Telescope
3.2.2 Preparations on the Blanco Telescope
3.3 First Light! (Alistair Walker, CTIO)
Chapter 4: Commissioning t he Dark Energy Camera on the Blanco Telescope
4.1 Commissioning
4.2 The days and nights following First Light
4.3 Donuts at DECam
4.4 The transition to SV
Chapter 5: The Dark Energy Survey Early Observations and Science Verification
5.1 Getting in gear
5.2 The SV plan
5.3 The ‘eyeball squad’
5.4 Early SV phase
5.5 The SV phase is extended
5.6 SV results and accomplishments
5.7 The impact of SV data
Reference
Chapter 6: DES as a Big Data Machine Part I: The Dark Energy Survey Data Management System
6.1 What is the Dark Energy Survey Data Management?
6.2 Early DESDM
6.3 Intermediate development of DESDM
6.3.1 Splitting up the pipelines
6.3.2 A stronger storage solution
6.3.3 Realistic test data for the community pipeline
6.3.4 Taming hostile codes
6.4 DESDM at present and looking to the future
Chapter 7: DES as a Big Data Machine Part II: Source Extractor and the Dark Energy Survey Science Portal
7.1 Analyzing large data sets: The Dark Energy Survey Science Portal solution (Luiz da Costa and Angelo Fausti)
7.1.1 Monitoring the quality of the raw data with Quick Reduce
7.1.2 Exploration of DES processed data
7.1.3 End-to-end processing
7.2 SExtractor and image analysis (Emmanuel Bertin)
7.2.1 SExtractor
7.2.2 Image stacking
7.2.3 Moving to multi-exposure image analysis
7.2.4 Improving deblending and the road ahead
References
Chapter 8: The Dark Energy Survey Strategy and Calibration
8.1 Constituent surveys within the Dark Energy Survey
8.2 Wide survey
8.2.1 Depth, exposures and image quality
8.2.2 Hexes and tilings
8.2.3 Footprint
8.2.4 Quality cuts
8.3 Time-domain survey
8.4 Schedule
8.5 Tactics
8.6 Photometric calibration
Part II: Dark Energy Science
Chapter 9: Type Ia Supernovae
9.1 Introduction to supernovae
9.1.1 Types of SN
9.1.2 Superluminous SN
9.2 Cosmology from SN
9.3 Strategy for SN observing with DECam
9.3.1 SN simulations
9.3.2 SN pipeline
9.4 Spectroscopic follow-up of SN
9.5 Year 3 unblinding
References
Chapter 10: Large-Scale Structure of the Universe
10.1 Introduction
10.2 Large-scale structure of the universe
10.3 Baryon acoustic oscillations
10.4 Measuring large-scale structure
10.5 Large-scale structure in DES
10.6 Baryon acoustic oscillations in DES
10.7 Looking to the future
References
Chapter 11: Weak Gravitational Lensing
11.1 Introduction
11.2 Weak gravitational lensing
11.3 Weak lensing and dark energy
11.4 Three regimes of weak lensing
11.5 Systematic uncertainties
11.6 From observations to cosmology
11.7 Weak lensing in DES
11.8 DES Year 1 weak lensing catalogues
11.9 DES Year 1 weak lensing mass map
11.10 Looking to the future
References
Chapter 12: Galaxy Clusters
12.1 Galaxy clusters
12.2 Cosmology from galaxy clusters
12.3 Galaxy clusters in DES
12.4 Measuring cluster mass
12.4.1 X-ray emission
12.4.2 The Sunyaev-Zel’dovich effect
12.5 Clusters beyond cosmology
Reference
Chapter 13: Theory and Combined Probes
13.1 From data to knowledge
13.2 Introducing the 3 × 2pt correlation function
13.2.1 Galaxy clustering
13.2.2 Galaxy–galaxy lensing
13.2.3 Cosmic shear
13.2.4 Three is the magic number – 3 × 2pt
13.3 Models, parameters and nuisance
13.4 Covariance
13.4.1 Enter the matrix
13.4.2 Two heads are better than one
13.5 Blinding
13.6 DESY1 3 × 2pt results
13.7 Beyond 3 × 2pt
13.8 Coming soon
References
Chapter 14: Spectroscopic Redshifts
14.1 Spectroscopic redshift
14.2 Spectroscopic redshifts in DES
14.3 OzDES
Chapter 15: Photometric Redshifts
15.1 Measuring photometric redshifts
15.2 Validating photometric redshifts
15.2.1 Validation from COSMOS
15.2.2 Validation from cross-correlation
15.3 Future work
References
Chapter 16: Simulating the Dark Energy Survey
16.1 Introduction to simulations
16.2 N-body
16.3 Simulations in DES – Of MICE and Buzzards
16.3.1 BUZZARD
16.3.2 MICE (Pablo Fosalba)
16.3.3 HALOGEN – BAO mocks
16.3.4 BALROG (Brian Yanny and Yuanyuan Zhang)
16.4 Using the galaxy catalogue simulations
References
Part III: Non-Dark Energy Science
Chapter 17: Galaxy Evolution
17.1 The Dark Energy Survey – A goldmine for galaxy evolution studies
17.2 Luminosity and stellar mass function
17.3 Galaxy environment
17.4 Evolution of galaxy properties in clusters
17.5 Galaxy biasing
17.6 Galaxy structure and morphology
17.7 Galaxy intrinsic alignments
17.8 Galaxies in the early universe
References
Chapter 18: Quasars
18.1 Inescapable
18.2 Evolution of quasars
18.3 Enter DES
18.4 The plan
18.5 Reverberation mapping
18.6 Using OzDES
18.7 Discovery
18.8 Future
References
Chapter 19: Strong Gravitational Lensing
19.1 Strong gravitational lensing
19.2 What can we learn from strong gravitational lensing?
19.3 Strong lensing in DES
19.3.1 Identifying strong lenses
19.3.2 Science!
References
Chapter 20: Stellar, Milky Way and Local Group Science
20.1 The Milky Way
20.1.1 Brown dwarfs in the galactic disc
20.1.2 Red dwarfs
20.1.3 White dwarfs
20.1.4 Galactic open clusters
20.1.5 Variable stars
20.1.6 Galactic stellar streams
20.2 The Local Group
20.2.1 Local Group globular clusters
20.2.2 Stellar structure at the outskirts of the LMC
20.2.3 Milky Way satellite dwarf galaxies
References
Chapter 21: Solar System Science
21.1 Introduction
21.2 Near-Earth asteroid of DOOM!
21.3 The working group begins
21.4 A treasure trove of transients
21.5 Finding ‘DeeDee’
21.6 Planet Nine from outer space
21.7 Going nuts about Caju
21.8 Looking back
References
Chapter 22: Optical Follow-ups to Gravitational Wave Events
22.1 A long time ago...
22.2 Gravitational waves 101
22.3 Putting the Dark Energy Survey GW team together
22.3.1 Developing the strategy
22.4 GW150914 – This is not a rehearsal
22.5 GW170817 – Discovery
22.5.1 Multi-messenger astrophysics
22.6 Standard siren?
22.7 Looking forward – Reflecting back
References
Part IV: Reflections and Outlook
Chapter 23: An Anthropology Angle: Credit and Uncertainty in the Dark Energy Survey
23.1 Introduction
23.2 Background literature
23.3 Credit and uncertainty: Science and infrastructure
23.4 Uncertainty and credit: Scientific knowledge and social relationships
23.5 Credit and certainty: Truth and mythology
23.6 Conclusion
References
Chapter 24: A Philosopher’s Look at the Dark Energy Survey: Reflections on the Use of the Bayes Factor in Cosmology
24.1 Introduction
24.2 DES Y1 results
24.3 On the Bayes factor
24.3.1 Context-dependence of standards of evidence along the Jeffreys scale
24.3.2 Relative versus absolute evidential measures
24.3.3 Dimensionality and nested models
24.3.4 Simplifications and sensitivity to priors
24.3.5 The Bartlett paradox and wide priors
24.3.6 The Bayes factor as Occam’s razor?
24.4 Philosophical coda
Acknowledgements
References
Chapter 25: Artists’ Reflections
Chapter 26: At the Edge of the Abyss: A Poem for the Dark Energy Survey
Chapter 27: The Dark Energy Survey and the Future of Dark Energy
27.1 Past
27.2 Present
27.3 Future
References
Appendix A: The US Department of Energy Approval Process
Appendix B: The Dark Energy Survey Collaboration Meeting Group Photos
Index
