OpenUniverse2024: A shared, simulated view of the sky for the next generation of cosmological surveys (2501.05632v2)

Abstract: The OpenUniverse2024 simulation suite is a cross-collaboration effort to produce matched simulated imaging for multiple surveys as they would observe a common simulated sky. Both the simulated data and associated tools used to produce it are intended to uniquely enable a wide range of studies to maximize the science potential of the next generation of cosmological surveys. We have produced simulated imaging for approximately 70 deg$^2$ of the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) Wide-Fast-Deep survey and the Nancy Grace Roman Space Telescope High-Latitude Wide-Area Survey, as well as overlapping versions of the ELAIS-S1 Deep-Drilling Field for LSST and the High-Latitude Time-Domain Survey for Roman. OpenUniverse2024 includes i) an early version of the updated extragalactic model called Diffsky, which substantially improves the realism of optical and infrared photometry of objects, compared to previous versions of these models; ii) updated transient models that extend through the wavelength range probed by Roman and Rubin; and iii) improved survey, telescope, and instrument realism based on up-to-date survey plans and known properties of the instruments. It is built on a new and updated suite of simulation tools that improves the ease of consistently simulating multiple observatories viewing the same sky. The approximately 400 TB of synthetic survey imaging and simulated universe catalogs are publicly available, and we preview some scientific uses of the simulations.

• The paper introduces the OpenUniverse2024 simulation suite, producing 70 deg² of realistic imaging data for LSST and Roman survey strategies.
• It employs sophisticated extragalactic models and detailed transient event simulations to improve optical and infrared photometry accuracy.
• The simulations enable joint calibration and pipeline development that reduce systematic uncertainties and boost transient detection efficiency.

OpenUniverse2024: A Simulated Framework for Cosmological Surveys

The paper "OpenUniverse2024: A Shared, Simulated View of the Sky for the Next Generation of Cosmological Surveys" introduces the OpenUniverse2024 simulation suite. This suite represents a collaborative effort across multiple astronomical collaborations, aimed at producing simulated imaging data harmonized with upcoming cosmological surveys. The paper provides a detailed description of how these simulations support future survey missions, with an emphasis on the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) and the Nancy Grace Roman Space Telescope.

Simulation Framework and Components

OpenUniverse2024 is ambitious in its scope, simulating approximately 70 deg² for both the LSST Wide-Fast-Deep survey and the Roman High-Latitude Wide-Area Survey, as well as deep-drilling fields for both observatories. The suite integrates multiple components to produce realistic simulation data:

1. Extragalactic Models: Utilizing an improved extragalactic model called Diffsky, the simulations present an enhanced realism in the optical and infrared photometry of objects. The use of advanced galaxy modeling techniques, including the GalSampler approach, has allowed for high-fidelity SED generation crucial for survey preparations.
2. Transient Phenomena: The list of simulated transients includes diverse supernova types, tidal disruption events, and kilonovae. SED extensions to cover infrared wavelengths ensure that the simulations remain relevant for Roman's survey capabilities, particularly in the time-domain applications.
3. Realism Enhancements: The simulations incorporate up-to-date survey plans and detailed instrument modelings, addressing several limitations of earlier simulation efforts by improving factors such as survey cadence, PSF modeling, and observing conditions.

Survey Design and Scientific Implications

The paper outlines the structured simulation of specific survey components:

• Wide-Fast-Deep & Deep-Drilling Fields: For LSST, a detailed simulation reflecting a rolling cadence strategy was implemented. This strategy aids in mitigating systematic uncertainties and maximizing transient detection capabilities.
• High-Latitude and Time-Domain Surveys: The Roman surveys were simulated with meticulous attention to the spatial setups and instrument configurations, tailored towards both wide-area surveys and time-domain investigations.

The simulations serve crucial roles in several aspects:

• Joint Calibration & Analysis: Overlapping observational data from LSST and Roman are shown to offer complementary insights that mitigate survey systematics, such as photo-z inference improvements and accurate deblending.
• Pipeline Development: The simulations drive the development of pipelines, particularly in transient detection and photometry, supporting early preparations and testing before actual survey operations commence.

The data products from OpenUniverse2024, including truth catalog tables and simulated images, are publicly accessible, facilitating widespread use and verification by the astronomical community.

Future Directions and Observational Synergy

While OpenUniverse2024 provides significant advancements in simulated survey data, the paper acknowledges current limitations and known issues, such as the precision of galaxy SEDs and technical challenges in transient modeling. Looking ahead, the integration of Euclid VIS survey data and further refinement of simulation parameters remain priorities. The collaborative nature of this project underlines the growing trend towards multi-survey synergy, highlighting the collective scientific gains from shared astronomical endeavors.

In conclusion, OpenUniverse2024 sets a foundational framework poised to transform how upcoming cosmological surveys will be executed and analyzed, fostering an environment of joint scientific discovery across various next-generation observatories.