WFIRST Deep Fields Anton Koekemoer (STScI) on behalf of the WFIRST Deep Field WG http://wfirst.wikispaces.com/deep+field
Overall scope / charter Explore WFIRST extragalactic deep field considerations: various science cases (incl SNe, galaxies, AGN, LSS) observational constraints (Zodi, extinction, schedulability) tie-in with other facilities (LSST, Euclid, PFS, ELTs, other) WG includes representation from each of the WFIRST science teams that could require extragalactic deep fields: SNe (incl members from both Foley & Perlmutter SITs) Galaxies, AGN (incl members from EXPO, Cosmic dawn SITs) cosmology/lss (incl members from Dore SIT, also HLS) also Euclid, LSST representation (Capak, Rhodes, Newman) Discussions & telecons since Mar 2016
SNe considerations Work from both SN SITs (Ryan Foley SIT, and Alex Kim + David Rubin on behalf of Perlmutter SIT) over the past year achieve broad consensus on the following preferences: low E(B-V) ~ 0.05 mag (or less if possible) CVZ preferable (note: SN losses in non-cvz can't be easily recovered just with longer scheduling windows because of visibility cutoffs; would instead imply more epochs extending beyond current scope of nominal mission lifetime) low Zodi preferable to avoid shallower detection limits Whether or not IFC is used: impacts role of ancillary data from other facilities/instruments, in considering whether to split fields between CVZ-S vs N
SN fields and reddening in CVZ Map of E(B-V) < 0.05 in WFIRST CVZ (from Ryan Foley) green is E(B-V)~0.05, white is E(B-V)~0 Requiring LSST would exclude any regions > dec +40
SNe: impact of non-cvz locations Calculations by David Rubin showing significant SNe losses due to visibility constraints for several non-cvz fields (some of these also have Zodi levels ~3-6x higher than CVZ)
EXPO (GO) and related science Generally two categories of "deep field" for other science "Medium deep" eg ~10 sq deg: would benefit significantly from spatial overlap with SN fields, in fact probably requiring this to achieve the science balance of filters/depths aims at significant depth increase across several bands, beyond what is required for SNe spatial overlap could also enable substantial overlapping grism program, opening interesting new scientific parameter space Ultra deep, eg ~1 sq deg or less (just ~1-2 pointings): relatively little benefit from overlap with shallower SN field location likely driven more by existing fields with ancillary data
Example GO deep field areas from LSST summary: EXPO team may continue discussions with LSST about additional deep drilling fields with WFIRST synergy
Conclusions to date: For SN science, CVZ remains the best choice: Zodi, E(B-V), and schedulability all work against non-cvz Currently considering pros/cons of CVZ-S vs N (impacted by IFC descope, also availability of other facilities/instruments) Non-SN science (incl galaxies, AGN, and LSS) can be broadly accommodated by two types of "deep field": "medium" deep field, similar size to SN field (eg ~10 sg deg) benefit most from being on top of SN field; may include grism "ultra deep" field, smaller size (eg ~1 sq deg) can be more easily decoupled from SN fields and placed elsewhere, with ancillary data important (incl non-cvz fields, eg CDFS etc) Ancillary facilities play significant role in all cases
Next Steps Consolidate recommendations into whitepaper / report Discussion points moving forward, SN and non-sn science: CVZ-S location in the HLS with LSST overlap CVZ-N location with PFS accessibility non-cvz "equatorial" fields with good ancillary data Expand discussion to broader community (LSST, Euclid, etc) explore new LSST deep drilling field (eg CVZ-S?)? PFS-like spectroscopy in the south? LSST-like (and/or more Subaru imaging) in the north? Anyone welcome to join Deep Field WG and participate in further discussion (http://wfirst.wikispaces.com/deep+field)