Direct Optimal Mapping for 21cm Cosmology: A Demonstration with the Hydrogen Epoch of Reionization Array

Motivated by the desire for wide-field images with well-defined statistical properties for 21cm cosmology, we implement an optimal mapping pipeline that computes a maximum likelihood estimator for the sky using the interferometric measurement equation. We demonstrate this direct optimal mapping with data from the Hydrogen Epoch of Reionization (HERA) Phase I observations. After validating the pipeline with simulated data, we develop a maximum likelihood figure-of-merit for comparing four sky models at 166MHz with a bandwidth of 100kHz. The HERA data agree with the GLEAM catalogs to <10%. After subtracting the GLEAM point sources, the HERA data discriminate between the different continuum sky models, providing most support for the model from Byrne et al. 2021. We report the computation cost for mapping the HERA Phase I data and project the computation for the HERA 320-antenna data, both are feasible with a modern server. The algorithm is broadly applicable to other interferometers, and is valid for wide-field and non-coplanar arrays.

Reference:
Direct Optimal Mapping for 21cm Cosmology: A Demonstration with the Hydrogen Epoch of Reionization Array, Zhilei XuJacqueline N. HewittKai-Feng ChenHongguen KimJoshua S. DillonNicholas S. KernMiguel F. MoralesBryna J. HazeltonRuby ByrneNicolas FagnoniEloy de Lera AcedoZara AbdurashidovaTyrone AdamsJames E. AguirrePaul AlexanderZaki S. AliRushelle BaartmanYanga BalfourAdam P. BeardsleyGianni BernardiTashalee S. BillingsJudd D. BowmanRichard F. BradleyPhilip BullJacob BurbaSteven CareyChris L. CarilliCarina ChengDavid R. DeBoerMatt DexterNico EksteenJohn ElyAaron Ewall-WiceRandall FritzSteven R. FurlanettoKingsley Gale-SidesBrian GlendenningDeepthi GorthiBradley GreigJasper GrobbelaarZiyaad HaldayJack HickishDaniel C. JacobsAustin JuliusMacCalvin KarisebJoshua KerriganPiyanat KittiwisitSaul A. KohnMatthew KolopanisAdam LanmanPaul La PlanteAdrian LiuAnita LootsYin-zhe MaDavid Harold Edward MacMahonLourence MalanCresshim MalgasKeith MalgasBradley MareroZachary E. MartinotAndrei MesingerMathakane MolewaTshegofalang MosianeSteven G. MurrayAbraham R. NebenBojan NikolicHans NuwegeldAaron R. ParsonsNipanjana PatraSamantha PieterseJonathan C. PoberNima Razavi-GhodsJames RobnettKathryn RosiePeter SimsCraig SmithHilton SwartsNithyanandan ThyagarajanPieter Van Van WyngaardenPeter K. G. WilliamsHaoxuan Zheng, submitted to ApJ, arXiv:2204.06021