Superclustering with the Atacama Cosmology Telescope and Dark Energy
  Survey: I. Evidence for thermal energy anisotropy using oriented stacking
  The Cosmic Web contains filamentary structure on a wide range of scales. On
the largest scales, superclustering aligns multiple galaxy clusters along
inter-cluster bridges, visible through their thermal Sunyaev-Zel'dovich signal
in the Cosmic Microwave Background. We demonstrate a new, flexible method to
analyze the hot gas signal from multi-scale extended structures. We use a
Compton-$y$ map from the Atacama Cosmology Telescope (ACT) stacked on redMaPPer
cluster positions from the optical Dark Energy Survey (DES). Cutout images from
the $y$ map are oriented with large-scale structure information from DES galaxy
data such that the superclustering signal is aligned before being overlaid. We
find evidence for an extended quadrupole moment of the stacked $y$ signal at
the 3.5$\sigma$ level, demonstrating that the large-scale thermal energy
surrounding galaxy clusters is anisotropically distributed. We compare our
ACT$\times$DES results with the Buzzard simulations, finding broad agreement.
Using simulations, we highlight the promise of this novel technique for
constraining the evolution of anisotropic, non-Gaussian structure using future
combinations of microwave and optical surveys.
