Rahul Datta
A5060902969- Radio Astronomy Observations and Technology
- Superconducting and THz Device Technology
- Galaxies: Formation, Evolution, Phenomena
- Cosmology and Gravitation Theories
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Dark Matter and Cosmic Phenomena
- Particle Detector Development and Performance
- Astrophysics and Star Formation Studies
- Adaptive optics and wavefront sensing
- Photonic and Optical Devices
- Stellar, planetary, and galactic studies
- Radio Frequency Integrated Circuit Design
- Optical Coatings and Gratings
- History and Developments in Astronomy
- CCD and CMOS Imaging Sensors
- Antenna Design and Optimization
- Planetary Science and Exploration
- Microwave Engineering and Waveguides
- Atmospheric aerosols and clouds
- Computational Physics and Python Applications
- Gamma-ray bursts and supernovae
- Astro and Planetary Science
University of Chicago
2023-2025
Johns Hopkins University
2018-2024
Bloomberg (United States)
2021
University of Michigan
2012-2020
Goddard Space Flight Center
2017-2018
Michigan United
2014-2016
Indian Space Research Organisation
2008
University of Jammu
2002
We present new arcminute-resolution maps of the Cosmic Microwave Background temperature and polarization anisotropy from Atacama Cosmology Telescope, using data taken 2013-2016 at 98 150 GHz. The cover more than 17,000 deg$^2$, deepest 600 deg$^2$ with noise levels below 10 $\mu$K-arcmin. use power spectrum derived almost 6,000 these to constrain cosmology. ACT enable a measurement angular scale features in both divergence-like anisotropy, tracing velocity density last-scattering. From one...
We present the temperature and polarization angular power spectra of CMB measured by Atacama Cosmology Telescope (ACT) from 5400 deg$^2$ 2013-2016 survey, which covers $>$15000 at 98 150 GHz. For this analysis we adopt a blinding strategy to help avoid confirmation bias and, related this, show numerous checks for systematic error done before unblinding. Using likelihood cosmological constrain secondary sources anisotropy foreground emission, derive "CMB-only" spectrum that extends...
We present the temperature and polarization angular power spectra measured by Atacama Cosmology Telescope Polarimeter (ACTPol). analyze night-time data collected during 2013-14 using two detector arrays at 149 GHz, from 548 deg$^2$ of sky on celestial equator. use these spectra, with MBAC camera ACT 2008-10, in combination Planck WMAP to estimate cosmological parameters temperature, polarization, temperature-polarization cross-correlations. find new ACTPol be consistent LCDM model. The...
We report on measurements of the cosmic microwave background (CMB) and celestial polarization at 146 GHz made with Atacama Cosmology Telescope Polarimeter (ACTPol) in its first three months observing. Four regions sky covering a total 270 square degrees were mapped an angular resolution $1.3'$. The map noise levels four are between 11 17 $\mu$K-arcmin. present TT, TE, EE, TB, EB, BB power spectra from these regions. observed E-mode spectrum, displaying six acoustic peaks range...
The Atacama Cosmology Telescope (ACT) is designed to make high angular resolution measurements of anisotropies in the Cosmic Microwave Background (CMB) at millimeter wavelengths. We describe ACTPol, an upgraded receiver for ACT, which uses feedhorn-coupled, polarization-sensitive detector arrays, a 3 degree field view, 100 mK cryogenics with continuous cooling, and meta material anti-reflection coatings. ACTPol comprises three arrays separate cryogenic optics: two central frequency 148 GHz...
We report a measurement of the power spectrum cosmic microwave background (CMB) lensing from two seasons Atacama Cosmology Telescope Polarimeter (ACTPol) CMB data. The is extracted both temperature and polarization data using quadratic estimators. obtain results that are consistent with expectation best-fit Planck LCDM model over range multipoles L=80-2100, an amplitude A_lens = 1.06 +/- 0.15 (stat.) 0.06 (sys.) relative to Planck. Our gives sigma_8 Omega_m^0.25 0.643 0.054; including baryon...
We present a catalog of 182 galaxy clusters detected through the Sunyaev-Zel'dovich effect by Atacama Cosmology Telescope in contiguous 987.5 deg$^{2}$ field. The were as SZ decrements applying matched filter to 148 GHz maps that combine original ACT equatorial survey with data from first two observing seasons using ACTPol receiver. Optical/IR confirmation and redshift measurements come combination large public surveys our own follow-up observations. Where necessary, we measured photometric...
Optimal analyses of many signals in the cosmic microwave background (CMB) require map-level extraction individual components sky, rather than measurements at power spectrum level alone. To date, nearly all component separation CMB has been performed exclusively using satellite data. In this paper, we implement a method based on internal linear combination (ILC) approach which have designed to optimally account for anisotropic noise (in 2D Fourier domain) often found ground-based experiments....
This paper presents a maximum-likelihood algorithm for combining sky maps with disparate coverage, angular resolution and spatially varying anisotropic noise into single map of the sky. We use this to merge hundreds individual covering 2008-2018 ACT observing seasons, resulting in by far deepest released so far. also combine full Planck maps, that have best features both ACT: Planck's nearly white on intermediate large scales ACT's high-resolution sensitivity small scales. The cover over...
We present evidence of the gravitational lensing cosmic microwave background by 10(13) solar mass dark matter halos. Lensing convergence maps from Atacama Cosmology Telescope Polarimeter (ACTPol) are stacked at positions around 12 000 optically selected CMASS galaxies SDSS-III/BOSS survey. The mean signal is consistent with simulated halo profiles and favored over a null 3.2σ significance. This result demonstrates potential to probe distribution in galaxy group cluster
We present a new measurement of the kinematic Sunyaev-Zel'dovich effect using data from Atacama Cosmology Telescope (ACT) and Baryon Oscillation Spectroscopic Survey (BOSS). Using 600 square degrees overlapping sky area, we evaluate mean pairwise baryon momentum associated with positions 50,000 bright galaxies in BOSS DR11 Large Scale Structure catalog. A non-zero signal arises large-scale motions halos containing sample galaxies. The fits an analytical model well, optical depth to microwave...
The increasing scale of cryogenic detector arrays for sub-millimeter and millimeter wavelength astrophysics has led to the need large aperture, high index refraction, low loss, refracting optics. Silicon with n = 3.4, relatively thermal conductivity is a nearly optimal material these purposes, but requires an antireflection (AR) coating broad bandwidth, reflectance, matched coefficient expansion. We present AR curved silicon optics comprised subwavelength features cut into lens surface...
The Cosmology Large Angular Scale Surveyor (CLASS) observes the polarized cosmic microwave background (CMB) over angular scales of 1$^\circ \lesssim \theta \leq$ 90$^\circ$ with aim characterizing primordial gravitational waves and reionization. We report on on-sky performance CLASS Q-band (40 GHz), W-band (90 dichroic G-band (150/220 GHz) receivers that have been operational at site in Atacama desert since June 2016, May 2018, September 2019, respectively. show noise-equivalent power...
Abstract Measurement of the largest angular scale ( ℓ < 30) features cosmic microwave background (CMB) polarization is a powerful way to constrain optical depth reionization and search for signature inflation through detection primordial B -modes. We present an analysis maps covering 73.6% sky made from 40 GHz channel Cosmology Large Angular Scale Surveyor (CLASS) 2016 August 2022 May. Taking advantage measurement stability enabled by front-end modulation excellent conditions Atacama...
We present a measurement of the gravitational lensing Cosmic Microwave Background (CMB) temperature and polarization fields obtained by cross-correlating reconstructed convergence signal from first season Atacama Cosmology Telescope Polarimeter data at 146 GHz with Infrared (CIB) fluctuations measured using Planck satellite. Using an effective overlap area 92.7 square degrees, we detect CMB large-scale structure statistical significance . Combining both gives detection significance. A B-mode...
We report on measurements of the polarization extragalactic sources at 148 GHz made during first two seasons Atacama Cosmology Telescope Polarization (ACTPol) survey. The survey covered 680 deg$^{2}$ sky celestial equator. 169 intensity-selected brighter than 30 mJy, that are predominantly Active Galactic Nuclei, presented. Above a total flux 215 mJy where noise bias removal in measurement is reliable, we detect 26 sources, 14 which have detection linear greater 3$\sigma_{p}$ significance....
Abstract The Cosmology Large Angular Scale Surveyor (CLASS) is a telescope array that observes the cosmic microwave background (CMB) over 75% of sky from Atacama Desert, Chile, at frequency bands centered near 40, 90, 150, and 220 GHz. CLASS measures large angular scale (1° ≲ θ 90°) CMB polarization to constrain tensor-to-scalar ratio r ∼ 0.01 level optical depth last scattering sample variance limit. This paper presents characterization 40 GHz during its first observation era, 2016...
We present measurements of large-scale cosmic microwave background (CMB) E-mode polarization from the Cosmology Large Angular Scale Surveyor (CLASS) 90 GHz data. Using 115 det-yr observations collected through 2024 with a variable-delay modulator, we achieved sensitivity $78\,\mathrm{\mu K\,arcmin}$, comparable to Planck at similar frequencies (100 and 143 GHz). The analysis demonstrates effective mitigation systematic errors addresses challenges large-angular-scale power recovery posed by...
The Simons Observatory (SO) experiment is a cosmic microwave background (CMB) located in the Atacama Desert, Chile. SO' s small aperture telescopes (SATs) consist of three designed for precise CMB polarimetry at large angular scales. Each SAT uses cryogenic rotating half-wave plate (HWP) as polarization modulator to mitigate atmospheric 1/f noise and other systematics. To realize efficient modulation over observation bands, we fabricated an achromatic HWP (AHWP) consisting sapphire plates...
We present an estimate of the Atacama Cosmology Telescope (ACT) detector polarization angle systematic uncertainty from optics perturbation analysis using polarization-sensitive ray tracing in CODE V optical design software. Uncertainties calibration CMB measurements can limit constraints on cosmic birefringence and other cosmological parameters sensitive to leakage. Our framework estimates uncertainties possible displacements lens positions orientations, anti-reflection coating (ARC)...