Angular BAO Forecasts for the IBIS Medium-Band Survey

Abstract

Ongoing and near-future spectroscopic surveys, such as DESI, DESI-II and Spec-S5, rely on imaging-based selections to construct uniform, three-dimensional tracers of large-scale structure. While spectroscopic data from these surveys constrain the baryonic acoustic oscillation (BAO) feature with high precision, the imaging surveys used for target selection can provide useful information on the angular diameter distance $D_A(z)$. In this work we explore the feasibility of angular BAO measurements for the Intermediate-Band Imaging Survey (IBIS) using recent constraints on clustering from a pilot survey spanning $2.2<z<3.5$. Through Fisher forecasts, we find that a 5000 deg$^2$ survey of LAEs with realistic bias, a tracer density of $2\times 10^{-4}$ (h/Mpc)$^3$ and interloper fraction $f_{\rm int}=10\%$ can constrain the BAO dilation parameter $\alpha$ at $z_{\rm eff}=2.8$ with a precision of 2.6\%, with dependence on the sample properties that is consistent with shot noise-dominated measurements. We then explore medium-band survey specifications for the planned Stage-V Spectroscopic Instrument (Spec-S5) and beyond, demonstrating the potential for precise high-redshift BAO measurements. Our forecasts motivate early measurements of BAO from these imaging surveys, which may inform later spectroscopic analyses.