The Dark Energy Survey: more than dark energy - an overview (1601.00329v3)

Abstract: This overview article describes the legacy prospect and discovery potential of the Dark Energy Survey (DES) beyond cosmological studies, illustrating it with examples from the DES early data. DES is using a wide-field camera (DECam) on the 4m Blanco Telescope in Chile to image 5000 sq deg of the sky in five filters (grizY). By its completion the survey is expected to have generated a catalogue of 300 million galaxies with photometric redshifts and 100 million stars. In addition, a time-domain survey search over 27 sq deg is expected to yield a sample of thousands of Type Ia supernovae and other transients. The main goals of DES are to characterise dark energy and dark matter, and to test alternative models of gravity; these goals will be pursued by studying large scale structure, cluster counts, weak gravitational lensing and Type Ia supernovae. However, DES also provides a rich data set which allows us to study many other aspects of astrophysics. In this paper we focus on additional science with DES, emphasizing areas where the survey makes a difference with respect to other current surveys. The paper illustrates, using early data (from `Science Verification', and from the first, second and third seasons of observations), what DES can tell us about the solar system, the Milky Way, galaxy evolution, quasars, and other topics. In addition, we show that if the cosmological model is assumed to be Lambda+ Cold Dark Matter (LCDM) then important astrophysics can be deduced from the primary DES probes. Highlights from DES early data include the discovery of 34 Trans Neptunian Objects, 17 dwarf satellites of the Milky Way, one published z > 6 quasar (and more confirmed) and two published superluminous supernovae (and more confirmed).

• The paper details DES’s multifaceted achievements by using wide-field imaging to constrain dark energy models and reveal unexpected astrophysical phenomena.
• It employs innovative photometric redshift techniques with data from the DECam on the Blanco Telescope to map cosmic structures across 5000 square degrees.
• The findings tighten cosmological parameters and expand knowledge of dark matter, dwarf galaxies, TNOs, and high-redshift quasars with significant empirical data.

Overview of the Dark Energy Survey: Beyond Dark Energy Studies

The paper "The Dark Energy Survey: More than Dark Energy - An Overview" provides a comprehensive evaluation of the Dark Energy Survey (DES) and its multifaceted scientific contributions beyond its primary focus on dark energy. Conducted with the DECam camera on the 4m Blanco Telescope at the Cerro Tololo Inter-American Observatory in Chile, DES aims to cover 5000 square degrees of the Southern sky in five optical filters. This endeavor has opened pathways not only in cosmology but also in addressing a variety of astrophysical questions.

Scientific Objectives and Discoveries

Cosmological Probes and Beyond

While the central Cosmological objective of DES is to constrain dark energy models by analyzing the distribution and growth of cosmic structures, the data encompass a rich volume of information utilized for studies in different astrophysical domains. The large-scale structure, cluster counts, weak lensing, and Type Ia supernovae surveys yield insights for understanding dark matter and testing alternative gravity models.

Solar System and Extragalactic Discoveries

• Trans-Neptunian Objects (TNOs): Early data from DES led to the discovery of 34 TNOs, providing an extraordinary window into the Solar System's distant dynamics. The survey's depth makes it particularly effective in uncovering high-inclination solar objects.
• Dwarf Galaxies: DES has contributed to the discovery of 17 new dwarf satellite galaxies of the Milky Way, enhancing knowledge of Galactic structure and the broader Local Group.
• Galaxy Evolution: The survey captures data across a range of redshifts, supporting the paper of galaxy evolution, environments, intrinsic alignments, and other properties. DES can effectively map the correlation between mass and morphological transformation over cosmic time scales.
• High-Redshift Galaxies and Quasars: In the field of high-redshift astrophysics, the survey has identified quasars at redshift $z > 6$, adding valuable data points for understanding early universe conditions and reionization processes.

Methodology and Analytical Techniques

A salient feature of DES is its ability to concurrently explore multiple cosmic phenomena via a single dataset, thanks to its breadth and depth. The survey employs photometric redshifts to create quasi-three-dimensional maps crucial for cosmological model testing. Additionally, innovative data processing and image analysis tools set a new standard in leveraging observational data across various scales.

Theoretical and Practical Implications

The wide-ranging discoveries by DES have profound cosmological and astrophysical implications:

• Cosmological Models: DES data provide robust empirical evidence to tighten constraints on parameters defining dark energy and dark matter distribution.
• Dark Matter and Dark Energy Insights: Through precise measurements of galaxy clustering and weak lensing, the survey aids in unraveling the underlying nature of dark matter and energy.
• Astrophysical Research: Beyond cosmology, DES data empower research in solar system dynamics, galaxy evolution, quasars' role in cosmic reionization, and intracluster light properties.

Future Prospects

The anticipated outcomes from the complete DES will be significant, with expectations to:

• Discover 50+ TNOs and substantially enhance the census of extragalactic and Galactic structures.
• Extend the catalog of high-redshift quasars and strong lensing systems, providing new opportunities for gravitational studies and spectroscopy.
• Bolster collaborations that integrate multi-wavelength data to further enrich the survey's legacy.

In summary, DES exemplifies how a cosmology-driven survey extends its utility across a spectrum of scientific inquiries. It is a precursor to even more comprehensive future surveys like LSST and Euclid, establishing groundwork in data acquisition, processing, and analysis that will benefit the broader astrophysical community.