We forecast constraints on cosmological parameters enabled by three surveys
conducted with SPT-3G, the third-generation camera on the South Pole Telescope.
The surveys cover separate regions of 1500, ...2650, and 6000 ${\rm deg}^{2}$ to
different depths, in total observing 25% of the sky. These regions will be
measured to white noise levels of roughly 2.5, 9, and 12 $\mu{\rm K-arcmin}$,
respectively, in CMB temperature units at 150 GHz by the end of 2024. The
survey also includes measurements at 95 and 220 GHz, which have noise levels a
factor of ~1.2 and 3.5 times higher than 150 GHz, respectively, with each band
having a polarization noise level ~$\sqrt{\text{2}}$ times higher than the
temperature noise. We use a novel approach to obtain the covariance matrices
for jointly and optimally estimated gravitational lensing potential bandpowers
and unlensed CMB temperature and polarization bandpowers. We demonstrate the
ability to test the $\Lambda{\rm CDM}$ model via the consistency of
cosmological parameters constrained independently from SPT-3G and Planck data,
and consider the improvement in constraints on $\Lambda{\rm CDM}$ extension
parameters from a joint analysis of SPT-3G and Planck data. The $\Lambda{\rm
CDM}$ cosmological parameters are typically constrained with uncertainties up
to ~2 times smaller with SPT-3G data, compared to Planck, with the two data
sets measuring significantly different angular scales and polarization levels,
providing additional tests of the standard cosmological model.
Frequency-domain multiplexing is a readout technique for transition edge sensor bolometer arrays used on modern CMB experiments, including the SPT-3G receiver. Here, we present design details and ...performance measurements for a low-parasitic frequency-domain multiplexing readout. Reducing the parasitic impedance of the connections between cryogenic components provides a path to improving both the crosstalk and noise performance of the readout. Reduced crosstalk will in turn allow higher multiplexing factors. We have demonstrated a factor of two improvement in parasitic resistance compared to SPT-3G hardware. Reduced parasitics also permits operation of lower-resistance bolometers, which enables better optimization of R\(_{\rm{bolo}}\) for improved readout noise performance. The prototype system exhibits noise performance comparable to SPT-3G readout hardware when operating SPT-3G detectors.
Abstract
We present a measurement of the cosmic microwave background lensing potential using 500 deg
2
of 150 GHz data from the SPTpol receiver on the South Pole Telescope. The lensing potential is ...reconstructed with signal-to-noise per mode greater than unity at lensing multipoles
L
≲ 250, using a quadratic estimator on a combination of cosmic microwave background temperature and polarization maps. We report measurements of the lensing potential power spectrum in the multipole range of 100 <
L
< 2000 from sets of temperature-only (
T
), polarization-only (POL), and minimum-variance (MV) estimators. We measure the lensing amplitude by taking the ratio of the measured spectrum to the expected spectrum from the best-fit Λ cold dark matter model to the
Planck
2015 TT + low
P
+ lensing data set. For the minimum-variance estimator, we find
A
MV
=
0.944
±
0.058
(
Stat
.
)
±
0.025
(
Sys
.
)
;
restricting to only polarization data, we find
A
POL
=
0.906
±
0.090
(
Stat
.
)
±
0.040
(
Sys
.
)
. Considering statistical uncertainties alone, this is the most precise polarization-only lensing amplitude constraint to date (10.1
σ
) and is more precise than our temperature-only constraint. We perform null tests and consistency checks and find no evidence for significant contamination.
Selectins bind to carbohydrate ligands in a calcium-dependent manner and play critical roles in host defense and possibly in tumor metastasis. To isolate peptides that mimic E-selectin ligands, we ...screened a phage peptide library using E-selectin as a target molecule. This attempt unexpectedly failed, probably because the binding affinity of E-selectin to its ligand is low. We then took an approach that is analogous to the isolation of anti-idiotype antibodies and were able to isolate peptides that bound to anticarbohydrate antibodies recognizing E-selectin ligands. These peptides, enriched for their binding to anti-Lewis A antibody, were found to bind to E-, P- and L-selectins in a calcium-dependent manner. Phage harboring the identified peptide IELLQAR and synthetic peptides having the same sequence inhibited the binding of sialyl Lewis X or sialyl Lewis A oligosaccharides to E-selectin. The adhesion of HL-60 and B16 melanoma cells expressing sialyl Lewis X to E-selectin was also inhibited by the phage-displaying IELLQAR peptide. Moreover, i.v. injected IELLQAR peptide inhibited the lung colonization of mouse B16 melanoma and human lung tumor cells expressing sialyl Lewis X. These results demonstrate that it is possible to isolate peptides mimicking carbohydrate ligands by screening the peptides for binding to anticarbohydrate antibodies and then using them to inhibit carbohydrate-dependent experimental tumor metastasis.
We present measurements of the E-mode polarization angular auto-power spectrum (EE) and temperature-E-mode cross-power spectrum (TE) of the cosmic microwave background (CMB) using 150 GHz data from ...three seasons of SPTpol observations. We report the power spectra over the spherical harmonic multipole range 50 < l <= 8000 and detect nine acoustic peaks in the EE spectrum with high signal-to-noise ratio. These measurements are the most sensitive to date of the EE and TE power spectra at l > 1050 and l > 1475, respectively. The observations cover 500 deg(2), a fivefold increase in area compared to previous SPTpol analyses, which increases our sensitivity to the photon diffusion damping tail of the CMB power spectra enabling tighter constraints on Lambda CDM model extensions. After masking all sources with unpolarized flux > 50 mJy, we place a 95% confidence upper limit on residual polarized point-source power of D-l= l(l + 1)C-l/2 pi < 0.107 mu K-2 at l = 3000, suggesting that the EE damping tail dominates foregrounds to at least l = 4050 with modest source masking. We find that the SPTpol data set is in mild tension with the Lambda CDM model (2.1 sigma), and different data splits prefer parameter values that differ at the similar to 1 sigma level. When fitting SPTpol data at l < 1000, we find cosmological parameter constraints consistent with those for Planck temperature. Including SPTpol data at l > 1000 results in a preference for a higher value of the expansion rate (H-0 = 71.3 +/- 2.1 km s(-1) Mpc(-1)) and a lower value for present-day density fluctuations (sigma(8) = 0.77 +/- 0.02).
In this paper, we describe QUBIC, an experiment that will observe the polarized microwave sky with a novel approach, which combines the sensitivity of state-of-the-art bolometric detectors with the ...systematic effects control typical of interferometers. QUBIC’s unique features are the so-called “self-calibration”, a technique that allows us to clean the measured data from instrumental effects, and its spectral imaging power, i.e., the ability to separate the signal into various sub-bands within each frequency band. QUBIC will observe the sky in two main frequency bands: 150 GHz and 220 GHz. A technological demonstrator is currently under testing and will be deployed in Argentina during 2019, while the final instrument is expected to be installed during 2020.
Kinetic inductance detectors (KIDs) are a promising technology for astronomical observations over a wide range of wavelengths in the mm and submm regime. Simple fabrication, in as little as one ...lithographic layer, and passive frequency-domain multiplexing, with readout of up to ∼1000 pixels on a single line with a single cold amplifier, make KIDs an attractive solution for high pixel-count detector arrays. Described in this dissertation is the design, fabrication, and testing of a 20-pixel prototype array of kinetic inductance detectors intended for cosmic microwave background (CMB) polarimetry in a band centered at 3 mm (100 GHz), which is an important band for CMB observations from the ground. We first show that the theoretical performance of idealized KIDs rivals that of their primary competitor detector technology, superconducting transition edge sensors (TESs). Next, we describe the design process, which employed both simulation and semianalytic calculations to optimize the resonant frequencies and optical coupling. Where a specific observing scenario was required to motivate design choices, we have used the QUBIC telescope, a bolometric interferometer designed to study the CMB polarization anisotropy initially from Alto Chorillos, Argentina and later from Dome C, Antarctica. Finally, we describe the fabrication and testing of three prototype arrays made with different materials and geometries. In two iterations of the device geometry, we demonstrate response to mm-wave illumination and improvements in control of pixel center frequencies and coupling quality factors. Additionally, we find that molybdenum is not well-suited to mm-wave KIDs because of excessive thermal dissipation resulting from double-gap behavior of superconducting molybdenum. Titanium nitride trilayers perform better, but exhibit complex and poorly-understood non-Mattis-Bardeen behavior. The superconducting properties of this material will need to be better understood before it can be used in successful mm-wave kinetic inductance detectors.
Q and U Bolometric Interferometer for Cosmology (QUBIC) is a Fizeau interferometer sensitive to linear polarisation, to be deployed at the Antarctic station of Dome C. This experiment in its final ...configuration will be operated at 97, 150 and 220 GHz and is intended to target CMB primordial B-modes in a multipole window
20
<
ℓ
<
150
. A sensitivity of
r
=
0.05
(95 % CL) can be reached by the first module alone, after 2 years of operation. Here we review in particular its working principles, and we show how the QUBIC interferometric configuration can be considered equivalent to a pupil-plane filtered imaging system. In this context, we show how our instrument can be self-calibrated. Finally, we conclude by showing an overview of the first dual-band module (150/220 GHz), which will serve also as a demonstrator for the subsequent units, and review the technological choices we made for each subsystem, with particular emphasis on the detection system.
We forecast constraints on cosmological parameters enabled by three surveys conducted with SPT-3G, the third-generation camera on the South Pole Telescope. The surveys cover separate regions of 1500, ...2650, and 6000 \({\rm deg}^{2}\) to different depths, in total observing 25% of the sky. These regions will be measured to white noise levels of roughly 2.5, 9, and 12 \(\mu{\rm K-arcmin}\), respectively, in CMB temperature units at 150 GHz by the end of 2024. The survey also includes measurements at 95 and 220 GHz, which have noise levels a factor of ~1.2 and 3.5 times higher than 150 GHz, respectively, with each band having a polarization noise level ~\(\sqrt{\text{2}}\) times higher than the temperature noise. We use a novel approach to obtain the covariance matrices for jointly and optimally estimated gravitational lensing potential bandpowers and unlensed CMB temperature and polarization bandpowers. We demonstrate the ability to test the \(\Lambda{\rm CDM}\) model via the consistency of cosmological parameters constrained independently from SPT-3G and Planck data, and consider the improvement in constraints on \(\Lambda{\rm CDM}\) extension parameters from a joint analysis of SPT-3G and Planck data. The \(\Lambda{\rm CDM}\) cosmological parameters are typically constrained with uncertainties up to ~2 times smaller with SPT-3G data, compared to Planck, with the two data sets measuring significantly different angular scales and polarization levels, providing additional tests of the standard cosmological model.
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