The PAU survey: Ly α intensity mapping forecast. Issue 3 (8th December 2020)

• Record Type: Journal Article
• Authors: Renard, Pablo; Gaztanaga, Enrique; Croft, Rupert; Cabayol, Laura; Carretero, Jorge; Eriksen, Martin; Fernandez, Enrique; García-Bellido, Juan; Miquel, Ramon; Padilla, Cristobal; Sanchez, Eusebio; Tallada-Crespí, Pau
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 501:Issue 3(2021)
• Page Start: 3883
• Page End: 3899
• Publication Date: 2020-12-08
• Subjects: large-scale structure of Universe -- cosmology: observations; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa3783
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: In this work, we explore the application of intensity mapping to detect extended Ly α emission from the IGM via cross-correlation of PAUS images with Ly α forest data from eBOSS and DESI. Seven narrow-band (FWHM = 13 nm) PAUS filters have been considered, ranging from 455 to 515 nm in steps of 10 nm, which allows the observation of Ly α emission in a range 2.7 < z < 3.3. The cross-correlation is simulated first in an area of 100 deg 2 (PAUS projected coverage), and second in two hypothetical scenarios: a deeper PAUS (complete up to i AB < 24 instead of i AB < 23, observation time ×6), and an extended PAUS coverage of 225 deg 2 (observation time ×2.25). A hydrodynamic simulation of size 400 Mpc h −1 is used to simulate both extended Ly α emission and absorption, while the foregrounds in PAUS images have been simulated using a lightcone mock catalogue. Using an optimistic estimation of uncorrelated PAUS noise, the total probability of a non-spurious detection is estimated to be 1.8 per cent and 4.5 per cent for PAUS-eBOSS and PAUS-DESI, from a run of 1000 simulated cross-correlations with different realisations of instrumental noise and quasar positions. The hypothetical PAUS scenarios increase this probability to 15.3 per cent (deeper PAUS) and 9.0 per cent (extended PAUS). With realistic correlated noise directly measured from PAUS images, these probabilities become negligible. Despite these negative results, some evidences suggest that this methodology may be more suitable to broad-band surveys.