AR 15810 (Archival Research)

Thu Jul 25 12:37:52 GMT 2024

Principal Investigator: Rogier Windhorst
PI Institution: Arizona State University
Investigators (xml)

Title: SKY-SURF: Panchromatic constraints on the Extragalactic Background Light and Zodical Light sources through all-sky foreground measurements
Cycle: 27

More than 95% of all photons in the HST Archive come from <5 AU. Yet, no precise panchromatic all-sky HST measurement of foregrounds exists. Project SKY-SURF will use HST's unique capability as absolute photometer to measure the absolute ~0.2-1.7 micron all-sky surface brightness (SB) from 57,302 ACS and WFC3 datasets in ~1100 fields. This Legacy dataset will constrain the diffuse UV-nearIR sky components: Zodiacal Light (ZL; inner solar system), Kuiper Belt Objects (KBOs; outer solar system), Diffuse Galactic Light (DGL), and Extragalactic Background Light (EBL). SKY-SURF will: (1) construct optimized panchromatic object catalogs, and an all-sky model of the (time-dependent) ZL, plus the DGL at ~10 deg resolution in the UV,U,B,V,r,i,z,Y,J,H filters free of discrete objects; (2) determine the integrated EBL to <3% by measuring panchromatic galaxy counts over 1100 HST fields, averaging over cosmic-variance effects on the EBL, as most of the EBL comes from 18-25 mag galaxies. We will use SKY-SURF's panchromatic ZL+DGL model to: (3) help recalibrate the direct EBL measurements to <4%; (4) assess how much DIFFUSE EBL can exist beyond the (extrapolated) discrete galaxy counts: Intra-galaxy Halo Light, Intra-Group Light, Intra-Cluster Light, etc.; (5) constrain the count-slope of very faint KBOs and grains in the outer solar system at R>28 mag, sampling their size-distribution from 1 km-0.1 mm; constrain the KBO flux-integral as a small excess on top of the Zodi foreground around Ecliptic latitude b_Ecl~0. (6) release to MAST panchromatic legacy products: optimized object catalogs, absolutely calibrated sky-SB data, and models of the ZL(t), DGL, and EBL.