Multiprobe constraints on early and late time dark energy

Abstract

We perform a multiprobe analysis combining cosmic microwave background (CMB) data from Planck and the Atacama Cosmology Telescope (ACT), ACT CMB lensing, and large-scale structure (LSS) measurements from the Dark Energy Spectroscopic Instrument (DESI), including DESI Legacy Imaging Survey (LS) galaxies and baryon acoustic oscillations (BAOs). We present the first $5\times 2$pt analysis of ACT DR6 lensing, DESI LS, and Planck ISW. Within $\hat{I}›$CDM, this yields $S_8=\ddot{I}{ƒ}_8(\hat{I}{\text{c◯}}_m/0.3{)}^{0.5}=0.819\pm 0.016$, in good agreement with primary CMB inferences and provides a sound-horizon-free Hubble constant constraint of $H_0=70.0\pm 4.4$ km s${}^{-1}$ Mpc${}^{-1}$. Then, combining with CMB primary and BAO, we reconfirm a CMB-BAO discrepancy in the $\hat{I}{\text{c◯}}_m$-$\frac{D_v}{r_d}$ plane, which is heightened when combining BAO with the $5\times 2$pt data vector. We explore two dark-energy extensions that may reconcile this: an early-time modification, early dark energy (EDE), and late-time dynamical dark energy (DDE) parameterized by $w_0{w}_a$. For CMB primary+BAO+$5\times 2$pt, we find a $3.3\ddot{I}ƒ$ preference for DDE over $\hat{I}›$CDM, while EDE is modestly favoured at $2.3\ddot{I}ƒ$. The models address different shortcomings of $\hat{I}›$CDM: DDE relaxes the neutrino mass bound ($M_{\hat{I}}½<0.17$eV vs. $<0.050$eV under $\hat{I}›$CDM), making it compatible with neutrino oscillation measurements, while EDE raises the Hubble constant to $H_0=70.5\pm 1.2\mathrm{km}{\mathrm{s}}^{-1}\mathrm{Mp}{\mathrm{c}}^{-1}$, easing the discrepancy with SH0ES. However, neither model resolves both issues simultaneously. Our analysis indicates that both DDE and EDE remain viable extensions of $\hat{I}›$CDM within current uncertainties and demonstrates the capacity of combined probes to place increasingly stringent constraints on cosmological parameters.

26 pages, 15 figures, comments welcome!