The Atacama Cosmology Telescope: measurement and analysis of 1D beams for DR4

Lungu, Marius; Storer, Émilie; Hasselfield, Matthew; Duivenvoorden, Adriaan J.; Calabrese, E.; Chesmore, Grace E.; Choi, Steve K.; Dunkley, Jo; Dünner, Rolando; Gallardo, Patricio A.; Golec, Joseph E.; Guan, Yilun; Hill, J. Colin; Hincks, Adam D.; Hubmayr, Johannes; Madhavacheril, Mathew S.; Mallaby-Kay, Maya; McMahon, Jeff; Moodley, Kavilan; Næss, Sigurd; Nati, F.; Niemack, Michael D.; Page, Lyman A.; Partridge, B.; Puddu, Roberto; Schillaci, A.; Sifón, Cristobál; Staggs, Suzanne T.; Sunder, Dhaneshwar D.; Wollack, Edward J.; Xu, Zhilei

doi:10.1088/1475-7516/2022/05/044

Cited by 9 publications

(13 citation statements)

References 61 publications

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“…We first check if systematic temperature-to-polarization leakage in the ACT maps could bias our measurement of TE. Following Lungu et al (2022), the expected T → E leakage is modeled as a leakage beam  B ℓ T E that is determined from ACT Q and U maps of Uranus. To first order, the expected bias to the TE spectrum is given by…”

Section: Polarization Analysismentioning

confidence: 99%

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

Córdova Rosado,

Hensley,

Clark

et al. 2024

ApJ

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We present a cross-correlation analysis between 1 ′ resolution total intensity and polarization observations from the Atacama Cosmology Telescope (ACT) at 150 and 220 GHz and 15″ 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.

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Section: Polarization Analysismentioning

confidence: 99%

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

Córdova Rosado,

Hensley,

Clark

et al. 2024

ApJ

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“…The cross-polar component is small in amplitude and should be studied together with the instrument's HWP performance. As planets are mostly unpolarized, observed polarization would be the result of T-to-P leakage, which the HWP failed to prevent (see Section 5 of Lungu et al 2022). This part of the analysis is left for future work.…”

Section: Instrument Design and Beam Modelingmentioning

confidence: 99%

“…Both the mapmaking and beam fitting are based on methods developed for the Atacama Cosmology Telescope (ACT; Hasselfield et al 2013;Lungu et al 2022). The main new method development for this paper is the noise mitigation approach described in Section 4.1.…”

Section: Analysis Pipelinementioning

confidence: 99%

“…To avoid this bias, we use a specialized filter-and-bin mapmaker that uses our knowledge of the planet's position to build a filter that removes as much of the atmosphere as possible while leaving the planet's signal almost untouched (see Hasselfield et al 2013;Choi et al 2020). In particular, if we assume that the planet's signal is entirely contained inside a mask with radius θ mask around its location, and that the noise is correlated with covariance matrix C n , then we can use all of the data outside of the mask to make a prediction about the noise inside the mask and subtract it (Lungu et al 2022):…”

Section: Mapmaking and Low-level Processingmentioning

confidence: 99%

“…Beam calibration techniques for CMB telescopes have been investigated in a number of publications (see, e.g., Aikin et al 2010;Keating et al 2013;Hasselfield et al 2013;Planck Collaboration VII et al 2016;BICEP2/Keck Array XI et al 2019;Lungu et al 2022). This paper adds to the existing literature by investigating the observational requirements and capabilities for beam reconstruction for the SO SATs.…”

Section: Introductionmentioning

confidence: 97%

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The Simons Observatory: Beam Characterization for the Small Aperture Telescopes

Dachlythra,

Duivenvoorden,

Gudmundsson

et al. 2024

ApJ

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We use time-domain simulations of Jupiter observations to test and develop a beam reconstruction pipeline for the Simons Observatory Small Aperture Telescopes. The method relies on a mapmaker that estimates and subtracts correlated atmospheric noise and a beam fitting code designed to compensate for the bias caused by the mapmaker. We test our reconstruction performance for four different frequency bands against various algorithmic parameters, atmospheric conditions, and input beams. We additionally show the reconstruction quality as a function of the number of available observations and investigate how different calibration strategies affect the beam uncertainty. For all of the cases considered, we find good agreement between the fitted results and the input beam model within an ∼1.5% error for a multipole range ℓ = 30–700 and an ∼0.5% error for a multipole range ℓ = 50–200. We conclude by using a harmonic-domain component separation algorithm to verify that the beam reconstruction errors and biases observed in our analysis do not significantly bias the Simons Observatory r-measurement

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Impact of beam far side-lobe knowledge in the presence of foregrounds for LiteBIRD

Leloup,

Patanchon,

Errard

et al. 2024

J. Cosmol. Astropart. Phys.

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We present a study of the impact of a beam far side-lobe lack of knowledge on the measurement of the Cosmic Microwave Background B-mode signal at large scale. Beam far side-lobes induce a mismatch in the transfer function of Galactic foregrounds between the dipole and higher multipoles which degrads the performances of component separation methods. This leads to foreground residuals in the CMB map. It is expected to be one of the main source of systematic effects in future CMB polarization observations. Thus, it becomes crucial for all-sky survey missions to take into account the interplays between beam systematic effects and all the data analysis steps. LiteBIRD is the ISAS/JAXA second strategic large-class satellite mission and is dedicated to target the measurement of CMB primordial B modes by reaching a sensitivity on the tensor-to-scalar ratio r of σ(r) ≤ 10-3 assuming r = 0. The primary goal of this paper is to provide the methodology and develop the framework to carry out the end-to-end study of beam far side-lobe effects for a space-borne CMB experiment. We introduce uncertainties in the beam model, and propagate the beam effects through all the steps of the analysis pipeline, most importantly including component separation, up to the cosmological results in the form of a bias δr. As a demonstration of our framework, we derive requirements on the calibration and modeling for the LiteBIRD's beams under given assumptions on design, simulation, component separation method and allocated error budget. In particular, we assume a parametric method of component separation with no mitigation of the far side-lobes effect at any stage of the analysis pipeline. We show that δr is mostly due to the integrated fractional power difference between the estimated beams and the true beams in the far side-lobes region, with little dependence on the actual shape of the beams, for low enough δr. Under our set of assumptions, in particular considering the specific foreground cleaning method we used, we find that the integrated fractional power in the far side-lobes should be known at the level of ∼ 10-4, to achieve the required limit on the bias δr < 1.9 × 10-5. The framework and tools developed for this study can be easily adapted to provide requirements under different design, data analysis frameworks and for other future space-borne experiments, such as PICO or CMB-Bharat. We further discuss the limitations of this framework and potential extensions to circumvent them.

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The Atacama Cosmology Telescope: measurement and analysis of 1D beams for DR4

Cited by 9 publications

References 61 publications

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

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

The Simons Observatory: Beam Characterization for the Small Aperture Telescopes

Impact of beam far side-lobe knowledge in the presence of foregrounds for LiteBIRD

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