| Abstract: | Baryon Acoustic Oscillations (BAO) have become the state-of-the-art tool of precision cosmology in the last two decades since their first detection in 2005. Using BAO, recent DESI DR2 results hinting at evolving dark energy, a model beyond Lambda-CDM, at the 2.8 to 4.2 sigma level, suggesting that a revolution in Cosmology may be within reach of the next generation of BAO analyses. Precision is now the bottleneck: statistical noise comprised of cosmic variance (CV) and shot noise (SN) dominate the BAO measurement. As CV is mitigated by ever-larger survey volumes, SN becomes dominant, particularly for the sparse, high-redshift tracers (e.g. quasars) that probe ever-deeper into the expansion history of the Universe. In this talk I present a novel method that could mitigate SN by exploiting the bias enhancement of tracers in over-dense environments: selecting tracers above a density threshold defined on a smoothed field, the method trades number density for clustering bias in a controlled way, possibly tightening the constraint on the BAO dilation parameter in some setups. I will discuss how the method is cross-checked on several simulated halo catalogs and Zel'dovich approximation mocks, all stressed into a SN-dominated regime, emulating the relevant range between DESI ELG and quasar densities. |