Cosmological Constraints from Multiple Probes in the Dark Energy Survey

The combination of multiple observational probes has long been advocated as a powerful technique to constrain cosmological parameters, in particular dark energy. The Dark Energy Survey has measured 207 spectroscopically confirmed type Ia supernova light curves, the baryon acoustic oscillation feature, weak gravitational lensing, and galaxy clustering. Here we present combined results from these probes, deriving constraints on the equation of state, $w$, of dark energy and its energy density in the Universe. Independently of other experiments, such as those that measure the cosmic microwave background, the probes from this single photometric survey rule out a Universe with no dark energy, finding $w=-0.80_{-0.11}^{+0.09}$. The geometry is shown to be consistent with a spatially flat Universe, and we obtain a constraint on the baryon density of ${\mathrm{\Omega }}_b=0.069_{-0.012}^{+0.009}$ that is independent of early Universe measurements. These results demonstrate the potential power of large multiprobe photometric surveys and pave the way for order of magnitude advances in our constraints on properties of dark energy and cosmology over the next decade.

Figure 1

Constraints on the present-day dark energy density ${\mathrm{\Omega }}_{\mathrm{\Lambda }}$ and matter density ${\mathrm{\Omega }}_m$, relative to the critical density, in an $o\mathrm{CDM}$ model with marginalized curvature and neutrino mass density. We compare the constraint from DES data alone (black contours), including information from weak gravitational lensing, large-scale structure, SNe Ia, and photometric BAO, to the best available external data (green contours), combining information from the CMB, SNe Ia, and spectroscopic BAO. We identify the flat model (${\mathrm{\Omega }}_k=0$) with a dotted line and distinguish accelerating and decelerating universes with a dashed line. Contours represent the 68% and 95% confidence limits (CL).

Figure 2

Constraints on the dark energy equation of state $w$ and ${\mathrm{\Omega }}_m$ in a $w\mathrm{CDM}$ model with fixed curvature (${\mathrm{\Omega }}_k=0$) and marginalized neutrino mass density. We compare constraints from the DES data alone (black contours) to the best available external data (green contours), as in Fig. 1, but also show the impact of including a low-redshift SNe Ia data set (Low-$z$) to anchor the DES SNe Ia as done in Ref. [19] (blue contours). Each component of the DES analysis was fully blinded.