COSMOGLOBE DR1 results Eskilt, J. R.; Watts, D. J.; Aurlien, R. ...
Astronomy and astrophysics (Berlin),
11/2023, Letnik:
679
Journal Article
Recenzirano
Odprti dostop
Cosmic birefringence is a parity-violating effect that might have rotated the plane of the linearly polarized light of the cosmic microwave background (CMB) by an angle
β
since its emission. This ...angle has recently been measured to be nonzero at a statistical significance of 3.6
σ
in the official
Planck
PR4 and 9-year WMAP data. In this work, we constrain
β
using the reprocessed B
EYOND
P
LANCK
LFI and C
OSMOGLOBE
DR1 WMAP polarization maps. These novel maps have both lower systematic residuals and a more complete error description than the corresponding official products. Foreground
EB
correlations could bias measurements of
β
, and while thermal dust
EB
emission has been argued to be statistically nonzero, no evidence for synchrotron
EB
power has been reported. Unlike the dust-dominated
Planck
HFI maps, the majority of the LFI and WMAP polarization maps are instead dominated by synchrotron emission. Simultaneously constraining
β
and the polarization miscalibration angle,
α
, of each channel, we find a best-fit value of
β
= 0.35° ±0.70° with LFI and WMAP data only. When including the
Planck
HFI PR4 maps, but fitting
β
separately for dust-dominated,
β
> 70 GHz
, and synchrotron-dominated channels,
β
≤70 GHz
, we find
β
≤70 GHz
= 0.53° ±0.28°. This differs from zero with a statistical significance of 1.9
σ
, and the main contribution to this value comes from the LFI 70 GHz channel. While the statistical significances of these results are low on their own, the measurement derived from the LFI and WMAP synchrotron-dominated maps agrees with the previously reported HFI-dominated constraints, despite the very different astrophysical and instrumental systematics involved in all these experiments.
We present the first application of the C
OSMOGLOBE
analysis framework by analyzing nine-year WMAP time-ordered observations that uses similar machinery to that of B
EYOND
P
LANCK
for the
Planck
Low ...Frequency Instrument (LFI). We analyzed only the
Q
-band (41 GHz) data and report on the low-level analysis process based on uncalibrated time-ordered data to calibrated maps. Most of the existing B
EYOND
P
LANCK
pipeline may be reused for WMAP analysis with minimal changes to the existing codebase. The main modification is the implementation of the same preconditioned biconjugate gradient mapmaker used by the WMAP team. Producing a single WMAP
Q
1-band sample requires 22 CPU-hrs, which is slightly more than the cost of a
Planck
44 GHz sample of 17 CPU-hrs; this demonstrates that a full end-to-end Bayesian processing of the WMAP data is computationally feasible. In general, our recovered maps are very similar to the maps released by the WMAP team, although with two notable differences. In terms of temperature, we find a ∼2 μK quadrupole difference that most likely is caused by different gain modeling, while in polarization we find a distinct 2.5 μK signal that has been previously referred to as poorly measured modes by the WMAP team. In the C
OSMOGLOBE
processing, this pattern arises from temperature-to-polarization leakage from the coupling between the CMB Solar dipole, transmission imbalance, and sidelobes. No traces of this pattern are found in either the frequency map or TOD residual map, suggesting that the current processing has succeeded in modeling these poorly measured modes within the assumed parametric model by using
Planck
information to break the sky-synchronous degeneracies inherent in the WMAP scanning strategy.
BEYONDPLANCK Brilenkov, M.; Fornazier, K. S. F.; Hergt, L. T. ...
Astronomy and astrophysics (Berlin),
07/2023, Letnik:
675
Journal Article
Recenzirano
Odprti dostop
End-to-end simulations play a key role in the analysis of any high-sensitivity cosmic microwave background (CMB) experiment, providing high-fidelity systematic error propagation capabilities that are ...unmatched by any other means. In this paper, we address an important issue regarding such simulations, namely, how to define the inputs in terms of sky model and instrument parameters. These may either be taken as a constrained realization derived from the data or as a random realization independent from the data. We refer to these as posterior and prior simulations, respectively. We show that the two options lead to significantly different correlation structures, as prior simulations (contrary to posterior simulations) effectively include cosmic variance, but they exclude realization-specific correlations from non-linear degeneracies. Consequently, they quantify fundamentally different types of uncertainties. We argue that as a result, they also have different and complementary scientific uses, even if this dichotomy is not absolute. In particular, posterior simulations are in general more convenient for parameter estimation studies, while prior simulations are generally more convenient for model testing. Before B
EYOND
P
LANCK
, most pipelines used a mix of constrained and random inputs and applied the same hybrid simulations for all applications, even though the statistical justification for this is not always evident. B
EYOND
P
LANCK
represents the first end-to-end CMB simulation framework that is able to generate both types of simulations and these new capabilities have brought this topic to the forefront. The B
EYOND
P
LANCK
posterior simulations and their uses are described extensively in a suite of companion papers. In this work, we consider one important applications of the corresponding prior simulations, namely, code validation. Specifically, we generated a set of one-year LFI 30 GHz prior simulations with known inputs and we used these to validate the core low-level B
EYOND
P
LANCK
algorithms dealing with gain estimation, correlated noise estimation, and mapmaking.
With this contribution we show the readout electronics for kinetic inductance detectors (KIDs) that we are developing based on commercial IQ transceivers from National Instruments and using a Virtex ...5 class FPGA. It will be the readout electronics of the COSmic Monopole Observer (COSMO) experiment, a ground based cryogenic Martin–Puplett Interferometer searching for the cosmic microwave background spectral distortions. The readout electronics require a sampling rate in the range of tens of kHz, which is both due to a fast rotating mirror modulating the signal and the time constant of the COSMO KIDs. In this contribution we show the capabilities of our readout electronics using Niobium KIDs developed by Paris Observatory for our 5 K cryogenic system. In particular, we demonstrate the capability to detect 23 resonators from frequency sweeps and to readout the state of each resonator with a sampling rate of about 8 kHz. The readout is based on a finite-state machine where the first two states look for the resonances and generate the comb of tones, while the third one performs the acquisition of phase and amplitude of each detector in free running. Our electronics are based on commercial modules, which brings two key advantages: they can be acquired easily and it is relative simple to write and modify the firmware within the LabView environment in order to meet the needs of the experiment.
COSMO is a ground-based instrument to measure the spectral distortions (SD) of the Cosmic Microwave Background (CMB). In this paper, we present preliminary results of electromagnetic simulations of ...its reference blackbody calibrator.
HFSS
simulations provide a calibrator reflection coefficient of
R
∼
10
-
6
, corresponding to an emissivity
ϵ
=
1
-
R
=
0.999999
. We also provide a forecast for the instrument performance by using an ILC-based simulation. We show that COSMO can extract the isotropic Comptonization parameter (modeled as
|
y
|
=
1.77
·
10
-
6
) as
|
y
|
=
(
1.79
±
0.19
)
·
10
-
6
, in the presence of the main Galactic foreground (thermal dust) and of CMB anisotropies, and assuming perfect atmospheric emission removal.
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