Sampling a large cosmic volume is critical to discovering a statistical sample of the rarest structures and to studying their redshift evolution. The proposed survey (91 deg2) will sample a total of ~0.24 Gpc3, and will discover ~15 Coma progenitors (Mtoday > 1015M⊙) and tens of the most extreme LABs (> 100 kpc) at each redshift, enabling comprehensive studies of these rare objects for the first time. Breaking the volume into multiple fields will 1) minimize strong cosmic variance expected for massive structures; and 2) best utilize deep broadband data.
The criteria for field selection included the availability of deep broad-band imaging and synergy with other experiments, as summarized in Table 1. Our observation would spread over all seasons except for April-June. While all fields will be imaged with LSST over a ten-year period, the four LSST Deep Drilling Fields will reach sufficient sensitivities (r ∼ 27) within the first year of operation; in the EDF-S, LSST is expected to reach 10-year depth within the first 3 years. Three of our survey fields already have sufficiently deep ugrizy imaging from Subaru SSP; this will increase to five in Year 1 of LSST (2023) and all seven fields in LSST Year 3. Figure 1. shows the locations of each survey feild.
Table 1: Summary of Target Fields and Broad-Band Availability Timeline
Figure 1: Location of each field.