paper

Photometric IGM tomography with Subaru/HSC: the large-scale structure of Ly emitters and IGM transmission in the COSMOS field at

arXiv:2301.00373 · doi:10.1093/mnras/stad1376

Abstract

We present a novel technique called "photometric IGM tomography" to map the intergalactic medium (IGM) at in the COSMOS field. It utilizes deep narrow-band (NB) imaging to photometrically detect faint Ly forest transmission in background galaxies across the Subaru/Hyper-Suprime Cam (HSC)'s field of view and locate Ly emitters (LAEs) in the same cosmic volume. Using ultra-deep HSC images and Bayesian spectral energy distribution fitting, we measure the Ly forest transmission at along a large number () of background galaxies selected from the DEIMOS10k spectroscopic catalogue at and the SILVERRUSH LAEs at . We photometrically measure the mean Ly forest transmission and achieve a result consistent with previous measurements based on quasar spectra. We also measure the angular LAE-Ly forest cross-correlation and Ly forest auto-correlation functions and place an observational constraint on the large-scale fluctuations of the IGM around LAEs at . Finally, we present the reconstructed 2D tomographic map of the IGM, co-spatial with the large-scale structure of LAEs, at a transverse resolution of across in the COSMOS field at . We discuss the observational requirements and the potential applications of this new technique for understanding the sources of reionization, quasar radiative history, and galaxy-IGM correlations across . Our results represent the first proof-of-concept of photometric IGM tomography, offering a new route to examining early galaxy evolution in the context of the large-scale cosmic web from the epoch of reionization to cosmic noon.

27 pages, 21 figures, accepted by MNRAS, full tables available as online supplementary material

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