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1. COMAP Early Science. IV. Power Spectrum Methodology and Results

   https://doi.org/10.3847/1538-4357/ac63c5  

   Ihle, Håvard T. ; Borowska, Jowita ; Cleary, Kieran A. ; Eriksen, Hans Kristian ; Foss, Marie K. ; Harper, Stuart E. ; Kim, Junhan ; Lunde, Jonas G. S. ; Philip, Liju ; Rasmussen, Maren ; et al ( July 2022 , The Astrophysical Journal)

   We present the power spectrum methodology used for the first-season COMAP analysis, and assess the quality of the current data set. The main results are derived through the Feed–Feed Pseudo-Cross-Spectrum (FPXS) method, which is a robust estimator with respect to both noise modeling errors and experimental systematics. We use effective transfer functions to take into account the effects of instrumental beam smoothing and various filter operations applied during the low-level data processing. The power spectra estimated in this way have allowed us to identify a systematic error associated with one of our two scanning strategies, believed to be due to residual ground or atmospheric contamination. We omit these data from our analysis and no longer use this scanning technique for observations. We present the power spectra from our first season of observing, and demonstrate that the uncertainties are integrating as expected for uncorrelated noise, with any residual systematics suppressed to a level below the noise. Using the FPXS method, and combining data on scalesk= 0.051–0.62 Mpc⁻¹, we estimateP_CO(k) = −2. 7 ± 1.7 × 10⁴μK²Mpc³, the first direct 3D constraint on the clustering component of the CO(1–0) power spectrum in the literature.
2. BICEP/Keck. XVII. Line-of-sight Distortion Analysis: Estimates of Gravitational Lensing, Anisotropic Cosmic Birefringence, Patchy Reionization, and Systematic Errors

   https://doi.org/10.3847/1538-4357/acc85c  

   Ade, P. A. R. ; Ahmed, Z. ; Amiri, M. ; Barkats, D. ; Thakur, R. Basu ; Bischoff, C. A. ; Beck, D. ; Bock, J. J. ; Boenish, H. ; Bullock, E. ; et al ( May 2023 , The Astrophysical Journal)

   We present estimates of line-of-sight distortion fields derived from the 95 and 150 GHz data taken by BICEP2, BICEP3, and the Keck Array up to the 2018 observing season, leading to cosmological constraints and a study of instrumental and astrophysical systematics. Cosmological constraints are derived from three of the distortion fields concerning gravitational lensing from large-scale structure, polarization rotation from magnetic fields or an axion-like field, and the screening effect of patchy reionization. We measure an amplitude of the lensing power spectrum$A_L^{\varphi \varphi }=0.95\pm 0.20$. We constrain polarization rotation, expressed as the coupling constant of a Chern–Simons electromagnetic termg_aγ≤ 2.6 × 10⁻²/H_I, whereH_Iis the inflationary Hubble parameter, and an amplitude of primordial magnetic fields smoothed over 1 MpcB_1Mpc≤ 6.6 nG at 95 GHz. We constrain the rms of optical depth fluctuations in a simple “crinkly surface” model of patchy reionization, findingA^τ< 0.19 (2σ) for the coherence scale ofL_c= 100. We show that all of the distortion fields of the 95 and 150 GHz polarization maps are consistent with simulations including lensed ΛCDM, dust, and noise, with no evidence for instrumental systematics. In some cases, theEBandTBquadratic estimators presented here are more sensitive than our previous map-based null tests at identifyingmore »and rejecting spuriousB-modes that might arise from instrumental effects. Finally, we verify that the standard deprojection filtering in the BICEP/Keck data processing is effective at removing temperature to polarization leakage.

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3. The First CHIME/FRB Fast Radio Burst Catalog

   https://doi.org/10.3847/1538-4365/ac33ab  

   Amiri, Mandana ; Andersen, Bridget C. ; Bandura, Kevin ; Berger, Sabrina ; Bhardwaj, Mohit ; Boyce, Michelle M. ; Boyle, P. J. ; Brar, Charanjot ; Breitman, Daniela ; Cassanelli, Tomas ; et al ( December 2021 , The Astrophysical Journal Supplement Series)

   We present a catalog of 536 fast radio bursts (FRBs) detected by the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) Project between 400 and 800 MHz from 2018 July 25 to 2019 July 1, including 62 bursts from 18 previously reported repeating sources. The catalog represents the first large sample, including bursts from repeaters and nonrepeaters, observed in a single survey with uniform selection effects. This facilitates comparative and absolute studies of the FRB population. We show that repeaters and apparent nonrepeaters have sky locations and dispersion measures (DMs) that are consistent with being drawn from the same distribution. However, bursts from repeating sources differ from apparent nonrepeaters in intrinsic temporal width and spectral bandwidth. Through injection of simulated events into our detection pipeline, we perform an absolute calibration of selection effects to account for systematic biases. We find evidence for a population of FRBs—composing a large fraction of the overall population—with a scattering time at 600 MHz in excess of 10 ms, of which only a small fraction are observed by CHIME/FRB. We infer a power-law index for the cumulative fluence distribution of$\alpha =-1.40\pm 0.11(\mathrm{stat.}{)}_{-0.09}^{+0.06}(\mathrm{sys.})$, consistent with the −3/2more »expectation for a nonevolving population in Euclidean space. We find thatαis steeper for high-DM events and shallower for low-DM events, which is what would be expected when DM is correlated with distance. We infer a sky rate of$[820\pm 60(\mathrm{stat.}{)}_{-200}^{+220}(\mathrm{sys.})]/\mathrm{sky}/\mathrm{day}$above a fluence of 5 Jy ms at 600 MHz, with a scattering time at 600 MHz under 10 ms and DM above 100 pc cm⁻³.

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4. Estimating the feasibility of 21cm-Lyα synergies using the hydrogen Epoch of Reionization array

   https://doi.org/10.1093/mnras/stac486  

   Cox, Tyler A. ; Jacobs, Daniel C. ; Murray, Steven G. ( February 2022 , Monthly Notices of the Royal Astronomical Society)

   Cross-correlating 21cm and Lyα intensity maps of the Epoch of Reionization promises to be a powerful tool for exploring the properties of the first galaxies. Next-generation intensity mapping experiments such as the Hydrogen Epoch of Reionization Array (HERA) and SPHEREx will individually probe reionization through the power spectra of the 21cm and Lyα lines respectively, but will be limited by bright foregrounds and instrumental systematics. Cross-correlating these measurements could reduce systematics, potentially tightening constraints on the inferred astrophysical parameters. In this study, we present forecasts of cross-correlation taking into account the effects of exact uv-sampling and foreground filtering to estimate the feasibility of HERAxSPHEREx making a detection of the 21cm-Lyα cross-power spectrum. We also project the sensitivity of a cross-power spectrum between HERA and the proposed next-generation Cosmic Dawn Intensity Mapper. By isolating the sources of uncertainty, we explore the impacts of experimental limitations such as foreground filtering and Lyα thermal noise uncertainty have on making a detection of the cross-power spectrum. We then implement this strategy in a simulation of the cross-power spectrum and observational error to identify redshifts where fiducial 21cmFAST models predict the highest signal-to-noise detection (z ∼ 8). We conclude that detection of the SPHEREx-HERAmore »cross-correlation will require an optimistic level of 21cm foreground filtering, as well as deeper thermal noise integrations due to a lack of overlapping sensitive modes but for CDIM with its larger range of scales and lower noise forecast detection levels, may be possible even with stricter 21cm foreground filtering.

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5. A Simulation-based Method for Correcting Mode Coupling in CMB Angular Power Spectra

   https://doi.org/10.3847/1538-4357/ac562f  

   Leung, J. S. -Y. ; Hartley, J. ; Nagy, J. M. ; Netterfield, C. B. ; Shariff, J. A. ; Ade, P. A. R. ; Amiri, M. ; Benton, S. J. ; Bergman, A. S. ; Bihary, R. ; et al ( March 2022 , The Astrophysical Journal)

   Modern cosmic microwave background (CMB) analysis pipelines regularly employ complex time-domain filters, beam models, masking, and other techniques during the production of sky maps and their corresponding angular power spectra. However, these processes can generate couplings between multipoles from the same spectrum and from different spectra, in addition to the typical power attenuation. Within the context of pseudo-C_ℓbased,MASTER-style analyses, the net effect of the time-domain filtering is commonly approximated by a multiplicative transfer function,F_ℓ, that can fail to capture mode mixing and is dependent on the spectrum of the signal. To address these shortcomings, we have developed a simulation-based spectral correction approach that constructs a two-dimensional transfer matrix,$J_{\mathit{\ell }\mathit{\ell }\prime }$, which contains information about mode mixing in addition to mode attenuation. We demonstrate the application of this approach on data from the first flight of theSpiderballoon-borne CMB experiment.