---
author:
- 'E. de Carvalho,'
- 'A. Bernui,'
- 'G. C. Carvalho,'
- 'C. P. Novaes,'
- 'H. S. Xavier'
title: ' Angular Baryon Acoustic Oscillation measure at z=2.225 from the SDSS quasar survey '
---

Introduction {#sec1}
============

#### 

One of the most iconic and incomprehensible components of the universe is the [*dark energy*]{}, an unknown entity representing $\sim 70\%$ of the cosmos [@PLA-XIII]. A powerful approach to unveil the dark energy mysteries is searching for the Baryon Acoustic Oscillations (BAO) signature at different epochs to probe its time evolution [@PeeblesYu; @SZ; @seo-eisenstein; @weinberg; @eisenstein98; @Meiksin].

The BAO is a primordial phenomenon that imprinted a characteristic scale, the sound horizon $r_{s}$, in the spatial distribution of cosmic objects. Almost a decade of success mapping the large-scale distribution of luminous matter provided large, dense, and deep surveys of cosmological tracers of the universe evolution like luminous red galaxies, emission line galaxies, and quasars [@SDSS; @WIGGLEZ; @6dFGRS]. With these data, analyses of the two-point correlation function (2PCF) produced robust detections of the BAO signature in different data ensembles giving precise measurements of the distance-redshift relationship, mainly using luminous red galaxies [@Eisenstein05; @Cole05; @Wang], but also with clusters of galaxies [@Hong; 