Abstract
ABSTRACT We search for the baryon acoustic oscillations in the projected cross-correlation function binned into transverse comoving radius between the SDSS-IV DR16 eBOSS quasars and a dense photometric sample of galaxies selected from the DESI Legacy Imaging Surveys. We estimate the density of the photometric sample of galaxies in this redshift range to be about 2900 deg−2, which is deeper than the official DESI emission line galaxy selection, and the density of the spectroscopic sample is about 20 deg−2. In order to mitigate the systematics related to the use of different imaging surveys close to the detection limit, we use a neural network approach that accounts for complex dependences between the imaging attributes and the observed galaxy density. We find that we are limited by the depth of the imaging surveys that affects the density and purity of the photometric sample and its overlap in redshift with the quasar sample, which thus affects the performance of the method. When cross-correlating the photometric galaxies with quasars in the range 0.6 ≤ z ≤ 1.2, the cross-correlation function can provide better constraints on the comoving angular distance DM (6 per cent precision) compared to the constraint on the spherically averaged distance DV (9 per cent precision) obtained from the autocorrelation. Although not yet competitive, this technique will benefit from the arrival of deeper photometric data from upcoming surveys that will enable it to go beyond the current limitations we have identified in this work.
Highlights
The baryon acoustic oscillations (BAO) feature (Cole et al 2005; Eisenstein et al 2005) in the clustering of galaxies left by the baryon– photon plasma that propagated as sound waves until decoupling in the early Universe has emerged as a very robust way of measuring cosmic distances across time
We measure the monopole of the autocorrelation function of eBOSS DR16 quasars in the Northern Galactic cap (NGC)-Beijing-Arizona Sky Survey (BASS)/Mayall z-band Legacy Survey (MzLS) and Southern Galactic cap (SGC)-Dark Energy Camera Legacy Survey (DECaLS) regions separately and for the two redshift ranges we consider
We have used a sample of SDSS-IV eBOSS quasars between 0.6 ≤ z ≤ z1.5 and we have produced a high-density sample of galaxies using the DESI Legacy Imaging Surveys
Summary
The baryon acoustic oscillations (BAO) feature (Cole et al 2005; Eisenstein et al 2005) in the clustering of galaxies left by the baryon– photon plasma that propagated as sound waves until decoupling in the early Universe has emerged as a very robust way of measuring cosmic distances across time. The BAO measurement in samples of galaxies at different redshifts is a powerful geometrical test to probe the expansion history of the Universe in a complementary way to cosmic microwave background anisotropies (Planck Collaboration VI 2020) and to the Hubble diagram with Type Ia supernovae for the local Universe, such as the recent HST programme SH0ES (Riess et al 2018, 2019) and the Carnegie-Chicago Hubble programme (Freedman et al 2019). These various cosmological data sets have shown increasing evidence that the cosmic expansion has been accelerating for 6 billion yr. The current observations could be explained by more complex dark energy models with time-dependent properties or even a modification of general relativity at cosmological scales (e.g. Linder & Cahn 2007; Guzzo et al 2008)
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