Simulations of the WFIRST Supernova Survey and Forecasts of Cosmological Constraints

R. Hounsell, D. Scolnic, R. J. Foley, R. Kessler, V. Miranda, A. Avelino, R. C. Bohlin, A. V. Filippenko, J. Frieman, S. W. Jha, P. L. Kelly, R. P. Kirshner, K. Mandel, A. Rest, A. G. Riess, S. A. Rodney, L. Strolger

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The Wide Field InfraRed Survey Telescope (WFIRST) was the highest-ranked large space-based mission of the 2010 New Worlds, New Horizons decadal survey. It is now a NASA mission in formulation with a planned launch in the mid 2020s. A primary mission objective is to precisely constrain the nature of dark energy through multiple probes, including Type Ia supernovae (SN Ia). Here, we present the first realistic simulations of the WFIRST SN survey based on current hardware specifications and using open-source tools. We simulate SN light curves and spectra as viewed by the WFIRST wide-field channel (WFC) imager and integral field channel (IFC) spectrometer, respectively. We examine 11 survey strategies with different time allocations between the WFC and IFC, two of which are based upon the strategy described by the WFIRST Science Definition Team, which measures SN distances exclusively from IFC data. We propagate statistical and, crucially, systematic uncertainties to predict the Dark Energy Task Force figure of merit (FoM) for each strategy. Of the strategies investigated, we find the most successful to be WFC focused. However, further work in constraining systematics is required to fully optimize the use of the IFC. Even without improvements to other cosmological probes, the WFIRST SN survey has the potential to increase the FoM by more than an order of magnitude from the current values. Although the survey strategies presented here have not been fully optimized, these initial investigations are an important step in the development of the final hardware design and implementation of the WFIRST mission.

Original languageEnglish (US)
Article number23
JournalAstrophysical Journal
Issue number1
StatePublished - Nov 1 2018

Bibliographical note

Funding Information:
This manuscript is based upon work supported by the National Aeronautics and Space Administration (NASA) under contract No. NNG16PJ34C issued through the WFIRST Science Investigation Teams Program. It was also supported in part by the U.S. Department of Energy under contract DE-AC02-76CH03000. Analysis was done using the Midway-RCC computing cluster at the University of Chicago.

Funding Information:
R.H., D.S., and R.J.F. were supported in part by NASA grant 14-WPS14-0048. The UCSC group is supported in part by fellowships to R.J.F. from the Alfred P. Sloan Foundation and the David and Lucile Packard Foundation. D.S. and R.K. acknowledge support from the Kavli Institute for Cosmological Physics at the University of Chicago through National Science Foundation (NSF) grant PHY-1125897 and an endowment from the Kavli Foundation and its founder Fred Kavli. Hubble/ KICP Fellow D.S. is also supported by NASA through Hubble Fellowship grant HST-HF2-51383.001 awarded by the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. V.M. was supported in part by the Charles E. Kaufman Foundation, a supporting organization of the Pittsburgh Foundation. Supernova cosmology at the Harvard College Observatory is supported in part by the NSF through grants AST-1516854 and AST-1211196, and NASA grant NNX15AJ55G. R.P.K. and A.A.were supported in part by the RAISIN1 GO-13046 and RAISIN2 GO-14216 HST grants, which were administered by STScI. A.V.F. and P.L.K. received support from the Christopher R. Redlich Fund, the TABASGO Foundation, the Miller Institute for Basic Research in Science (U.C. Berkeley), and NASA/HST grants GO-14041 and GO-14199.


  • dark energy
  • space vehicles: instruments
  • supernovae: general
  • surveys
  • techniques: imaging spectroscopy

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