Darby Kramer
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View article: Cross-correlating the Patchy Screening and Kinetic Sunyaev–Zel’dovich Effects as a New Probe of Reionization
Cross-correlating the Patchy Screening and Kinetic Sunyaev–Zel’dovich Effects as a New Probe of Reionization Open
The kinetic Sunyaev–Zel’dovich effect (kSZ) and patchy screening effect are two complementary cosmic microwave background (CMB) probes of the reionization era. The kSZ effect is a relatively strong signal, but is difficult to disentangle f…
View article: The Atacama Cosmology Telescope: DR6 power spectra, likelihoods and ΛCDM parameters
The Atacama Cosmology Telescope: DR6 power spectra, likelihoods and ΛCDM parameters Open
We present power spectra of the cosmic microwave background (CMB) anisotropy in temperature and polarization, measured from the Data Release 6 maps made from Atacama Cosmology Telescope (ACT) data. These cover 19,000 deg 2 of sky in bands …
View article: The Atacama Cosmology Telescope: DR6 power spectrum foreground model and validation
The Atacama Cosmology Telescope: DR6 power spectrum foreground model and validation Open
We discuss the model of astrophysical emission at millimeter wavelengths used to characterize foregrounds in the multi-frequency power spectra of the Atacama Cosmology Telescope (ACT) Data Release 6 (DR6), expanding on Louis et al. (2025) …
View article: The Cosmic Microwave Background Optical Depth Constrains the Duration of Reionization
The Cosmic Microwave Background Optical Depth Constrains the Duration of Reionization Open
Recently, it was pointed out that invoking a large value of the cosmic microwave background (CMB) optical depth, τ CMB = 0.09, could help resolve tensions between Dark Energy Survey Instrument DR2 baryon acoustic oscillation data and the C…
View article: The CMB optical depth constrains the duration of reionization
The CMB optical depth constrains the duration of reionization Open
Recently, it was pointed out that invoking a large value of the CMB optical depth, $τ_{\rm CMB} = 0.09$, could help resolve tensions between DESI DR2 BAO data and the CMB. This is larger than the value of $τ_{\rm CMB} = 0.058$ measured fro…
View article: The Atacama Cosmology Telescope: DR6 Maps
The Atacama Cosmology Telescope: DR6 Maps Open
We present Atacama Cosmology Telescope (ACT) Data Release 6 (DR6) maps of the Cosmic Microwave Background temperature and polarization anisotropy at arcminute resolution over three frequency bands centered on 98, 150 and 220 GHz. The maps …
View article: The Atacama Cosmology Telescope: DR6 Constraints on Extended Cosmological Models
The Atacama Cosmology Telescope: DR6 Constraints on Extended Cosmological Models Open
We use new cosmic microwave background (CMB) primary temperature and polarization anisotropy measurements from the Atacama Cosmology Telescope (ACT) Data Release 6 (DR6) to test foundational assumptions of the standard cosmological model a…
View article: The Atacama Cosmology Telescope: DR6 Power Spectra, Likelihoods and $Λ$CDM Parameters
The Atacama Cosmology Telescope: DR6 Power Spectra, Likelihoods and $Λ$CDM Parameters Open
We present power spectra of the cosmic microwave background (CMB) anisotropy in temperature and polarization, measured from the Data Release 6 maps made from Atacama Cosmology Telescope (ACT) data. These cover 19,000 deg$^2$ of sky in band…
View article: Cross-correlating the patchy screening and kinetic Sunyaev-Zel'dovich effects as a new probe of reionization
Cross-correlating the patchy screening and kinetic Sunyaev-Zel'dovich effects as a new probe of reionization Open
The kinetic Sunyaev-Zel'dovich effect (kSZ) and patchy screening effect are two complementary cosmic microwave background (CMB) probes of the reionization era. The kSZ effect is a relatively strong signal, but is difficult to disentangle f…
View article: The Atacama Cosmology Telescope: <scp>r</scp>eionization kSZ trispectrum methodology and limits
The Atacama Cosmology Telescope: <span>r</span>eionization kSZ trispectrum methodology and limits Open
Patchy reionization generates kinematic Sunyaev–Zel’dovich (kSZ) anisotropies in the cosmic microwave background (CMB). Large-scale velocity perturbations along the line of sight modulate the small-scale kSZ power spectrum, leading to a tr…
View article: The Atacama Cosmology Telescope: Reionization kSZ trispectrum methodology and limits
The Atacama Cosmology Telescope: Reionization kSZ trispectrum methodology and limits Open
Patchy reionization generates kinematic Sunyaev-Zeldovich (kSZ) anisotropies in the cosmic microwave background (CMB). Large-scale velocity perturbations along the line of sight modulate the small-scale kSZ power spectrum, leading to a tri…
View article: Atacama Cosmology Telescope: High-resolution component-separated maps across one third of the sky
Atacama Cosmology Telescope: High-resolution component-separated maps across one third of the sky Open
Observations of the millimeter sky contain valuable information on a number of signals, including the blackbody cosmic microwave background (CMB), Galactic emissions, and the Compton-y distortion due to the thermal Sunyaev-Zel’dovich (tSZ)…
View article: The Atacama Cosmology Telescope: DR6 Gravitational Lensing Map and Cosmological Parameters
The Atacama Cosmology Telescope: DR6 Gravitational Lensing Map and Cosmological Parameters Open
We present cosmological constraints from a gravitational lensing mass map covering 9400 deg 2 reconstructed from measurements of the cosmic microwave background (CMB) made by the Atacama Cosmology Telescope (ACT) from 2017 to 2021. In comb…
View article: The Atacama Cosmology Telescope: A Measurement of the DR6 CMB Lensing Power Spectrum and Its Implications for Structure Growth
The Atacama Cosmology Telescope: A Measurement of the DR6 CMB Lensing Power Spectrum and Its Implications for Structure Growth Open
We present new measurements of cosmic microwave background (CMB) lensing over 9400 deg 2 of the sky. These lensing measurements are derived from the Atacama Cosmology Telescope (ACT) Data Release 6 (DR6) CMB data set, which consists of fiv…
View article: The Atacama Cosmology Telescope: A search for late-time anisotropic screening of the Cosmic Microwave Background
The Atacama Cosmology Telescope: A search for late-time anisotropic screening of the Cosmic Microwave Background Open
Since the formation of the first stars, most of the gas in the Universe has been ionized. Spatial variations in the density of this ionized gas generate cosmic microwave background anisotropies via Thomson scattering, a process known as th…
View article: The Atacama Cosmology Telescope: High-resolution component-separated maps across one-third of the sky
The Atacama Cosmology Telescope: High-resolution component-separated maps across one-third of the sky Open
Observations of the millimeter sky contain valuable information on a number of signals, including the blackbody cosmic microwave background (CMB), Galactic emissions, and the Compton-$y$ distortion due to the thermal Sunyaev-Zel'dovich (tS…
View article: SKYSURF-4: Panchromatic Hubble Space Telescope All-Sky Surface-brightness Measurement Methods and Results
SKYSURF-4: Panchromatic Hubble Space Telescope All-Sky Surface-brightness Measurement Methods and Results Open
The diffuse, unresolved sky provides most of the photons that the Hubble Space Telescope (HST) receives, yet remains poorly understood. The HST Archival Legacy program SKYSURF aims to measure the 0.2–1.6 μ m sky surface brightness (sky-SB)…
View article: SKYSURF-3: Testing Crowded Object Catalogs in the Hubble eXtreme Deep Field Mosaics to Study Sample Incompleteness from an Extragalactic Background Light Perspective
SKYSURF-3: Testing Crowded Object Catalogs in the Hubble eXtreme Deep Field Mosaics to Study Sample Incompleteness from an Extragalactic Background Light Perspective Open
Extragalactic background light (EBL) studies have revealed a significant discrepancy between direct measurements—via instruments measuring “bare” sky from which Zodiacal and Galactic light models are subtracted—and measurements of the inte…
View article: SKYSURF-4: Panchromatic HST All-Sky Surface-Brightness Measurement Methods and Results
SKYSURF-4: Panchromatic HST All-Sky Surface-Brightness Measurement Methods and Results Open
The diffuse, unresolved sky provides most of the photons that the Hubble Space Telescope (HST) receives, yet remains poorly understood. HST Archival Legacy program SKYSURF aims to measure the 0.2-1.6 $μ$m sky surface brightness (sky-SB) fr…
View article: SKYSURF: Constraints on Zodiacal Light and Extragalactic Background Light through Panchromatic HST All-sky Surface-brightness Measurements: II. First Limits on Diffuse Light at 1.25, 1.4, and 1.6 μm
SKYSURF: Constraints on Zodiacal Light and Extragalactic Background Light through Panchromatic HST All-sky Surface-brightness Measurements: II. First Limits on Diffuse Light at 1.25, 1.4, and 1.6 μm Open
We present the first results from the HST Archival Legacy project “SKYSURF.” As described in Windhorst et al., SKYSURF utilizes the large HST archive to study the diffuse UV, optical, and near-IR backgrounds and foregrounds in detail. Here…
View article: SKYSURF: Constraints on Zodiacal Light and Extragalactic Background Light through Panchromatic HST All-sky Surface-brightness Measurements. I. Survey Overview and Methods
SKYSURF: Constraints on Zodiacal Light and Extragalactic Background Light through Panchromatic HST All-sky Surface-brightness Measurements. I. Survey Overview and Methods Open
We give an overview and describe the rationale, methods, and testing of the Hubble Space Telescope (HST) Archival Legacy project “SKYSURF.” SKYSURF uses HST’s unique capability as an absolute photometer to measure the ∼0.2–1.7 μ m sky-surf…
View article: SKYSURF-3: Testing Crowded Object Catalogs in the Hubble eXtreme Deep Field Mosaics to Study Sample Incompleteness from an Extragalactic Background Light Perspective
SKYSURF-3: Testing Crowded Object Catalogs in the Hubble eXtreme Deep Field Mosaics to Study Sample Incompleteness from an Extragalactic Background Light Perspective Open
Extragalactic Background Light (EBL) studies have revealed a significant discrepancy between direct measurements -- via instruments measuring "bare" sky from which Zodiacal and Galactic light models are subtracted -- and measurements of th…
View article: SKYSURF: Constraints on Zodiacal Light and Extragalactic Background Light through Panchromatic HST All-Sky Surface-Brightness Measurements: I. Survey Overview and Methods
SKYSURF: Constraints on Zodiacal Light and Extragalactic Background Light through Panchromatic HST All-Sky Surface-Brightness Measurements: I. Survey Overview and Methods Open
We give an overview and describe the rationale, methods, and testing of the Hubble Space Telescope (HST) Archival Legacy project "SKYSURF." SKYSURF uses HST's unique capability as an absolute photometer to measure the ~0.2-1.7 $μ$m sky sur…
View article: SKYSURF: Constraints on Zodiacal Light and Extragalactic Background Light through Panchromatic HST All-Sky Surface-Brightness Measurements: II. First Limits on Diffuse Light at 1.25, 1.4, and 1.6 microns
SKYSURF: Constraints on Zodiacal Light and Extragalactic Background Light through Panchromatic HST All-Sky Surface-Brightness Measurements: II. First Limits on Diffuse Light at 1.25, 1.4, and 1.6 microns Open
We present the first results from the HST Archival Legacy project "SKYSURF." As described in Windhorst et al. 2022, SKYSURF utilizes the large HST archive to study the diffuse UV, optical, and near-IR backgrounds and foregrounds in detail.…