The Atacama Cosmology Telescope: Galactic Dust Structure and the Cosmic PAH Background in Cross-correlation with WISE

• Published in: The Astrophysical journal Vol. 960; no. 2; pp. 96 - 110
• Main Authors: Córdova Rosado, Rodrigo, Hensley, Brandon S., Clark, Susan E., Duivenvoorden, Adriaan J., Atkins, Zachary, Battistelli, Elia Stefano, Choi, Steve K., Dunkley, Jo, Hervías-Caimapo, Carlos, Li, Zack, Louis, Thibaut, Naess, Sigurd, Page, Lyman A., Partridge, Bruce, Sifón, Cristóbal, Staggs, Suzanne T., Vargas, Cristian, Wollack, Edward J.
• Format: Journal Article
• Language: English
• Published: Goddard Space Flight Center The American Astronomical Society 01.01.2024; American Astronomical Society/IOP; IOP Publishing; American Astronomical Society
• Subjects: Aromatic hydrocarbons; Astronomy; Astrophysics; Correlation analysis; Cosmic background radiation; Cosmic dust; Cosmology; Cross correlation; Dust; Dust continuum emission; Dust emission; Emission; Emission measurements; Galaxies; Infrared astronomy; Infrared photometry; Interstellar dust; Interstellar magnetic fields; Interstellar medium; Magnetic fields; Milky Way; Optics; Physics; Polarization; Polycyclic aromatic hydrocarbons; Power law; Sky surveys (astronomy); Spectra; Wavelengths
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ad05cd

We present a cross-correlation analysis between 1ʹ resolution total intensity and polarization observations from the Atacama Cosmology Telescope (ACT) at 150 and 220 GHz and 15ʺ mid-infrared photometry from the Wide-field Infrared Survey Explorer (WISE) over 107 12°.5 × 12°.5 patches of sky. We detect a spatially isotropic signal in the WISE×ACT TT cross-power spectrum at 30σ significance that we interpret as the correlation between the cosmic infrared background at ACT frequencies and polycyclic aromatic hydrocarbon (PAH) emission from galaxies in WISE, i.e., the cosmic PAH background. Within the Milky Way, the Galactic dust TT spectra are generally well described by power laws in ℓ over the range 103 < ℓ < 104, but there is evidence both for variability in the power-law index and for non-power-law behavior in some regions. We measure a positive correlation between WISE total intensity and ACT E-mode polarization at 1000 < ℓ ≲ 6000 at >3σ in each of 35 distinct ∼100 deg2 regions of the sky, suggesting that alignment between Galactic density structures and the local magnetic field persists to subparsec physical scales in these regions. The distribution of TE amplitudes in this ℓ range across all 107 regions is biased to positive values, while there is no evidence for such a bias in the TB spectra. This work constitutes the highest-ℓ measurements of the Galactic dust TE spectrum to date and indicates that cross-correlation with high-resolution mid-infrared measurements of dust emission is a promising tool for constraining the spatial statistics of dust emission at millimeter wavelengths.