DESI and other dark energy experiments in the era of neutrino mass measurements (1308.4164v2)

Abstract: We present Fisher matrix projections for future cosmological parameter measurements, including neutrino masses, dark energy, curvature, modified gravity, the inflationary perturbation spectrum, non-Gaussianity, and dark radiation. We focus on DESI and generally redshift surveys (BOSS, HETDEX, eBOSS, Euclid, and WFIRST), but also include CMB (Planck) and weak gravitational lensing (DES and LSST) constraints. The goal is to present a consistent set of projections, for concrete experiments, which are otherwise scattered throughout many papers and proposals. We include neutrino mass as a free parameter in most projections, as it will inevitably be relevant -- DESI and other experiments can measure the sum of neutrino masses to ~0.02 eV or better, while the minimum possible sum is ~0.06 eV. We note that the BAO-only use of galaxy clustering is substantially degraded as a dark energy probe in the presence of neutrino mass uncertainty -- using broadband galaxy power is critical, especially pushing it to as small a scale as possible, and big gains are achieved by combining lensing survey constraints with redshift survey constraints. We do not try to be especially innovative, e.g., in careful treatments of potential systematic errors -- these projections are intended as a straightforward baseline for comparison to more detailed analyses.

• The paper presents a comprehensive Fisher matrix analysis forecasting neutrino mass measurements, highlighting DESI's potential to achieve ≈0.02 eV precision.
• The study demonstrates that including neutrino mass uncertainty degrades Dark Energy parameter constraints, urging the need for more robust cosmological models.
• The analysis finds that overlapping survey strategies yield limited additional gains, underscoring the complementary strengths of redshift and lensing observations.

Examination of Dark Energy Experiments and Neutrino Mass Measurements

The paper authored by Font-Ribera et al. presents an in-depth analysis of several upcoming and proposed cosmological surveys, emphasizing their potential for measuring neutrino masses, Dark Energy parameters, and other critical cosmological factors. The paper primarily utilizes the Fisher matrix formalism to forecast the statistical capabilities of these experiments.

The research evaluates a cohort of cosmological surveys: DESI, BOSS, HETDEX, eBOSS, Euclid, and WFIRST, alongside CMB constraints from Planck and weak lensing constraints from DES and LSST. The paper intricately describes the predictive analysis performed using the Fisher matrix, focusing on a suite of 19 cosmological parameters, with a particular emphasis on neutrino masses, which are ubiquitous to the projections due to their potential impact on other cosmological measurements.

To illustrate the effectiveness of individual surveys and their combinations, the paper provides a comprehensive set of projections for different scenarios. Notably, DESI and similar experiments are projected to measure the sum of neutrino masses with a precision of approximately 0.02 eV, given the minimum possible sum of neutrino masses is about 0.06 eV. The results posit that DESI, when combined with Planck and possibly lensing surveys, will significantly advance our understanding of neutrino masses, potentially offering insights into the neutrino mass hierarchy.

The paper also emphasizes that neutrino mass uncertainty introduces a novel challenge in measuring Dark Energy parameters. The research demonstrates that while broadband galaxy power and lensing measurements can mitigate some of this uncertainty, the overall constraints on Dark Energy parameters degrade when accounting for unknown neutrino masses. This implies that future research must continue to integrate neutrino mass uncertainty as a free parameter in cosmological models to ensure robust predictions.

Moreover, the paper explores the potential of overlapping and non-overlapping redshift and photometric surveys. While overlapping surveys intuitively offer cross-correlation advantages, the research finds limited improvement in parameter constraints. This insight suggests that the unique strengths of redshift surveys (predominantly in fine radial resolution) and lensing surveys (in small-scale transverse mode prediction) cannot be substantially enhanced solely by overlap.

Future aspirations highlighted include a comprehensive exploitation of data from upcoming cosmological surveys, particularly enhancing the Fisher matrix model to incorporate systemic uncertainties more complexly. The anticipated synergy between advanced redshift surveys, such as DESI and Euclid, and photometric surveys, notably LSST, foreshadows a significant leap in understanding the universe's fundamental properties.

In conclusion, the importance of integrating neutrino mass as a critical parameter emerges as a major thesis of the paper. The multi-faceted approaches to data collection, driven by the expanded scope of upcoming surveys, promise to refine our understanding of cosmological constants significantly. Such advancements hold pronounced implications for tracking the universe's evolution and discerning the underlying physics of Dark Energy. The paper, while providing concrete measurements, underlines the methodological rigor required in evaluating cosmological parameters amidst overlapping systematic uncertainties and evolving observational capabilities.