J. S. Avva
A5003806085- Radio Astronomy Observations and Technology
- Superconducting and THz Device Technology
- Cosmology and Gravitation Theories
- Astrophysics and Cosmic Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Physics of Superconductivity and Magnetism
- Dark Matter and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Microwave Engineering and Waveguides
- Astronomy and Astrophysical Research
- Adaptive optics and wavefront sensing
- Precipitation Measurement and Analysis
- Antenna Design and Optimization
- Satellite Communication Systems
- Calibration and Measurement Techniques
- Thermal Radiation and Cooling Technologies
- Geophysics and Gravity Measurements
- Advanced Thermodynamic Systems and Engines
- Neutrino Physics Research
- Radio Frequency Integrated Circuit Design
- Advanced MIMO Systems Optimization
- Wireless Communication Networks Research
- Advanced Thermodynamics and Statistical Mechanics
- CCD and CMOS Imaging Sensors
- Optical Coatings and Gratings
University of California, Berkeley
2016-2022
University of California System
2018
University of Chicago
2015-2017
We present measurements of the $E$-mode ($EE$) polarization power spectrum and temperature-$E$-mode ($TE$) cross-power cosmic microwave background using data collected by SPT-3G, latest instrument installed on South Pole Telescope. This analysis uses observations a $1500\text{ }\text{ }{\mathrm{deg}}^{2}$ region at 95, 150, 220 GHz taken over four-month period in 2018. report binned values $EE$ $TE$ spectra angular multipole range $300\ensuremath{\le}\ensuremath{\ell}<3000$, multifrequency...
We report a B-mode power spectrum measurement from the cosmic microwave background (CMB) polarization anisotropy observations made using SPTpol instrument on South Pole Telescope. This work uses 500 deg$^2$ of data, five-fold increase over last release. As result, bandpower uncertainties have been reduced by more than factor two, and extends to lower multipoles: $52 < \ell 2301$. Data both 95 150 GHz are used, allowing for three cross-spectra: x GHz, GHz. is detected at very high...
Abstract We present cosmological constraints based on the cosmic microwave background (CMB) lensing potential power spectrum measurement from recent 500 deg 2 SPTpol survey, most precise CMB ground to date. fit a flat ΛCDM model reconstructed alone and in addition with other data sets: baryon acoustic oscillations (BAO), as well primary spectra Planck . The band powers are good agreement when analyzed combination full-sky data. With weak priors density parameters, provide 4% constraint...
In this paper, we describe the optimization of transition-edge-sensor (TES) detector arrays for thirdgeneration camera South Pole Telescope.The camera, which contains ∼16 000 detectors, will make high-angular-resolution maps temperature and polarization cosmic microwave background.Our key results are scatter in transition Ti/Au TESs is reduced by fabricating on a thin Ti(5 nm)/Au(5 nm) buffer layer thermal conductivity legs that support our islands dominated SiOx dielectric microstrip...
We present a catalog of galaxy cluster candidates detected in 100 square degrees surveyed with the SPTpol receiver on South Pole Telescope. The contains 89 signal-to-noise ratio greater than 4.6. are selected using Sunyaev-Zel'dovich effect at 95 and 150 GHz. Using both space- ground-based optical infrared telescopes, we have confirmed 81 as clusters. use these follow-up images archival to estimate photometric redshifts for 66 clusters spectroscopic observations obtain 13 systems. An...
We describe the observations and resultant galaxy cluster catalog from 2770 deg2 SPTpol Extended Cluster Survey (SPT-ECS). Clusters are identified via Sunyaev–Zel'dovich (SZ) effect confirmed with a combination of archival targeted follow-up data, making particular use data Dark Energy (DES). With incomplete we have as clusters 244 266 candidates at detection significance ξ ≥ 5 an additional 204 systems 4 < 5. The sample has median mass redshift z = 0.49, 44 strong gravitational lenses in...
Abstract We report an in situ measurement of the electric field attenuation length L α at radio frequencies for bulk ice Summit Station, Greenland, made by broadcasting radio-frequency signals vertically through and measuring relative power return ground bounce signal. find depth-averaged to be 75 MHz. While this has clear radioglaciological applications, clarity also implications detection ultra-high energy (UHE) astrophysical particles via their emission dielectric media such as ice....
The South Pole Telescope (SPT) is a millimeter-wavelength telescope designed for high-precision measurements of the cosmic microwave background (CMB). SPT measures both temperature and polarization CMB with large aperture, resulting in high resolution maps sensitive to signals across wide range angular scales on sky. With these data, has potential make broad cosmological measurements. These include constraining effect massive neutrinos large-scale structure formation as well cleaning...
Ultralight axionlike particles (ALPs) are compelling dark matter candidates because of their potential to resolve small-scale discrepancies between $\Lambda$CDM predictions and cosmological observations. Axion-photon coupling induces a polarization rotation in linearly polarized photons traveling through an ALP field; thus, as the local field oscillates time, distant static sources will appear oscillate with frequency proportional mass. We use observations cosmic microwave background from...
We study the polarisation properties of extragalactic sources at 95 and 150 GHz in SPTpol 500 deg$^2$ survey. estimate polarised power by stacking maps known source positions, correct for noise bias subtracting mean random positions maps. show that method is unbiased using a set simulated with similar to real find flux-weighted mean-squared fraction $\langle p^2 \rangle= [8.9\pm1.1] \times 10^{-4}$ $[6.9\pm1.1] 150~GHz full sample. This consistent values obtained sub-sample active galactic...
The third generation receiver for the South Pole Telescope, SPT-3G, will make extremely deep, arcminuteresolution maps of temperature and polarization cosmic microwave background. SPT-3G enable studies B-mode signature, constraining primordial gravitational waves as well effect massive neutrinos on structure formation in late universe. achieve exceptional sensitivity through a focal plane ~16,000 transition-edge sensor bolometers, an order magnitude more than current SPTpol receiver. uses...
We report new measurements of millimeter-wave power spectra in the angular multipole range $2000 \le \ell 11,000$ (angular scales $5^\prime \gtrsim \theta 1^\prime$). By adding 95 and 150\,GHz data from low-noise 500 deg$^2$ SPTpol survey to SPT-SZ three-frequency 2540 survey, we substantially reduce uncertainties these bands. These include contributions primary cosmic microwave background, infrared radio galaxies, thermal kinematic Sunyaev-Zel'dovich (SZ) effects. The favor a SZ (tSZ) at...
Abstract The cosmic microwave background (CMB) encodes information about the content and evolution of universe. presence light, weakly interacting particles impacts expansion history early universe, which alters temperature polarization anisotropies CMB. In this way, current measurements CMB place interesting constraints on neutrino energy density mass, as well abundance other possible light relativistic particle species. We present status an on-going 1500 sq. deg. survey with SPT-3G...
The third-generation South Pole Telescope camera (SPT-3G) improves upon its predecessor (SPTpol) by an order of magnitude increase in detectors on the focal plane. technology used to read out and control these detectors, digital frequency-domain multiplexing (DfMUX), is conceptually same as for SPTpol, but extended accommodate more detectors. A nearly 5× expansion readout operating bandwidth has enabled use this large plane, SPT-3G performance meets forecasting targets relevant science...
The SPT-3G receiver was commissioned in early 2017 on the 10-meter South Pole Telescope (SPT) to map anisotropies cosmic microwave background (CMB). New optics, detector, and readout technologies have yielded a multichroic, high-resolution, low-noise camera with impressive throughput sensitivity, offering potential improve our understanding of inflationary physics, astroparticle growth structure. We highlight several key features design principles new receiver, summarize its performance date.
The desire for higher sensitivity has driven ground-based cosmic microwave background (CMB) experiments to employ ever larger focal planes, which in turn require reimaging optics. Practical limits the maximum size of these optics motivates development quasi-optically-coupled (lenslet-coupled), multi-chroic detectors. These detectors can be sensitive across a broader bandwidth compared waveguide-coupled However, increase comes at cost: lenses (up $\sim$700 mm diameter) and lenslets ($\sim$5...
Detectors for cosmic microwave background (CMB) experiments are now essentially limited, so a straightforward alternative to improve sensitivity is increase the number of detectors. Large arrays multichroic pixels constitute an economical approach increasing detectors within given focal plane area. Here, we present fabrication large dual-polarized transition-edge-sensor (TES) bolometers South Pole Telescope third-generation CMB receiver (SPT-3G). The complete SPT-3G will have 2690 pixels,...