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 implement support for a cosmological parameter estimation algorithm in
Commander
and quantify its computational efficiency and cost. For a semi-realistic simulation similar to
Planck
LFI 70 GHz, ...we find that the computational cost of producing one single sample is about 20 CPU-hours and that the typical Markov chain correlation length is ∼100 samples. The net effective cost per independent sample is ∼2000 CPU-hours, in comparison with all low-level processing costs of 812 CPU-hours for
Planck
LFI and WMAP in C
OSMOGLOBE
Data Release 1. Thus, although technically possible to run already in its current state, future work should aim to reduce the effective cost per independent sample by one order of magnitude to avoid excessive runtimes, for instance through multi-grid preconditioners and/or derivative-based Markov chain sampling schemes. This work demonstrates the computational feasibility of true Bayesian cosmological parameter estimation with end-to-end error propagation for high-precision CMB experiments without likelihood approximations, but it also highlights the need for additional optimizations before it is ready for full production-level analysis.
COSMOGLOBE DR1 results Watts, D. J.; Basyrov, A.; Eskilt, J. R. ...
Astronomy and astrophysics (Berlin),
11/2023, Letnik:
679
Journal Article
Recenzirano
Odprti dostop
We present C
OSMOGLOBE
Data Release 1, which implements the first joint analysis of WMAP and
Planck
LFI time-ordered data, processed within a single Bayesian end-to-end framework. This framework ...directly builds on a similar analysis of the LFI measurements by the B
EYOND
P
LANCK
collaboration, and approaches the cosmic microwave background (CMB) analysis challenge through Gibbs sampling of a global posterior distribution, simultaneously accounting for calibration, mapmaking, and component separation. The computational cost of producing one complete WMAP+LFI Gibbs sample is 812 CPU-h, of which 603 CPU-h are spent on WMAP low-level processing; this demonstrates that end-to-end Bayesian analysis of the WMAP data is computationally feasible. We find that our WMAP posterior mean temperature sky maps and CMB temperature power spectrum are largely consistent with the official WMAP9 results. Perhaps the most notable difference is that our CMB dipole amplitude is 3366.2 ± 1.4 μK, which is 11 μK higher than the WMAP9 estimate and 2.5
σ
higher than B
EYOND
P
LANCK
; however, it is in perfect agreement with the HFI-dominated
Planck
PR4 result. In contrast, our WMAP polarization maps differ more notably from the WMAP9 results, and in general exhibit significantly lower large-scale residuals. We attribute this to a better constrained gain and transmission imbalance model. It is particularly noteworthy that the
W
-band polarization sky map, which was excluded from the official WMAP cosmological analysis, for the first time appears visually consistent with the
V
-band sky map. Similarly, the long standing discrepancy between the WMAP
K
-band and LFI 30 GHz maps is finally resolved, and the difference between the two maps appears consistent with instrumental noise at high Galactic latitudes. Relatedly, these updated maps allowed us for the first time to combine WMAP and LFI polarization data into a single coherent model of large-scale polarized synchrotron emission. Still, we identified a few issues that require additional work, including (1) low-level noise modeling; (2) large-scale temperature residuals at the 1–2 μK level; and (3) a strong degeneracy between the absolute
K
-band calibration and the dipole of the anomalous microwave emission component. We conclude that leveraging the complementary strengths of WMAP and LFI has allowed the mitigation of both experiments’ weaknesses, and resulted in new state-of-the-art WMAP sky maps. All maps and the associated code are made publicly available through the C
OSMOGLOBE
web page.
COSMOGLOBE DR1 results Eskilt, J R; Watts, D J; Aurlien, R ...
Astronomy & astrophysics,
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 3.6σ in the official Planck PR4 and 9-year WMAP data. In this work, we constrain β using the reprocessed BEYONDPLANCK LFI and COSMOGLOBE 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 1.9σ, 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.
COSMOGLOBE DR1 results Watts, D. J.; Fuskeland, U.; Aurlien, R. ...
Astronomy and astrophysics (Berlin),
06/2024, Letnik:
686
Journal Article
Recenzirano
We present the first model of full-sky polarized synchrotron emission that is derived from all WMAP and Planck LFI frequency maps. The basis of this analysis is the set of end-to-end reprocessed C ...OSMOGLOBE Data Release 1 (DR1) sky maps presented in a companion paper, which have significantly lower instrumental systematics than the legacy products from each experiment. We find that the resulting polarized synchrotron amplitude map has an average noise rms per 2° full width at half maximum (FWHM) beam of 3.2 μK at 30 GHz. This is 30% lower than the recently released B EYOND P LANCK model that included only LFI+WMAP Ka – V data, and 29% lower than the WMAP K -band map alone. The mean B -to- E power spectrum ratio is 0.39 ± 0.02, with amplitudes consistent with those measured previously by Planck and QUIJOTE. Assuming a power law model for the synchrotron spectral energy distribution and using the T – T plot method, we find a full-sky inverse noise-variance-weighted mean of the synchrotron polarized spectral index of β s = −3.07 ± 0.07 from the C OSMOGLOBE DR1 K band and 30 GHz, in good agreement with previous estimates. In summary, the novel C OSMOGLOBE DR1 synchrotron model is both more sensitive and systematically cleaner than similar previous models, and it has a more complete error description that is defined by a set of Monte Carlo posterior samples. We believe that these products are preferable over previous Planck and WMAP products for all synchrotron-related scientific applications, including simulations, forecasting, and component separation.
COSMOGLOBE DR1 results Watts, D J; Basyrov, A; Eskilt, J R ...
Astronomy & astrophysics,
11/2023, Letnik:
679
Journal Article
Recenzirano
Odprti dostop
We present COSMOGLOBE Data Release 1, which implements the first joint analysis of WMAP and Planck LFI time-ordered data, processed within a single Bayesian end-to-end framework. This framework ...directly builds on a similar analysis of the LFI measurements by the BEYONDPLANCK collaboration, and approaches the cosmic microwave background (CMB) analysis challenge through Gibbs sampling of a global posterior distribution, simultaneously accounting for calibration, mapmaking, and component separation. The computational cost of producing one complete WMAP+LFI Gibbs sample is 812 CPU-h, of which 603 CPU-h are spent on WMAP low-level processing; this demonstrates that end-to-end Bayesian analysis of the WMAP data is computationally feasible. We find that our WMAP posterior mean temperature sky maps and CMB temperature power spectrum are largely consistent with the official WMAP9 results. Perhaps the most notable difference is that our CMB dipole amplitude is 3366.2 ± 1.4 μK, which is 11 μK higher than the WMAP9 estimate and 2.5σ higher than BEYONDPLANCK; however, it is in perfect agreement with the HFI-dominated Planck PR4 result. In contrast, our WMAP polarization maps differ more notably from the WMAP9 results, and in general exhibit significantly lower large-scale residuals. We attribute this to a better constrained gain and transmission imbalance model. It is particularly noteworthy that the W-band polarization sky map, which was excluded from the official WMAP cosmological analysis, for the first time appears visually consistent with the V-band sky map. Similarly, the long standing discrepancy between the WMAP K-band and LFI 30 GHz maps is finally resolved, and the difference between the two maps appears consistent with instrumental noise at high Galactic latitudes. Relatedly, these updated maps allowed us for the first time to combine WMAP and LFI polarization data into a single coherent model of large-scale polarized synchrotron emission. Still, we identified a few issues that require additional work, including (1) low-level noise modeling; (2) large-scale temperature residuals at the 1–2 μK level; and (3) a strong degeneracy between the absolute K-band calibration and the dipole of the anomalous microwave emission component. We conclude that leveraging the complementary strengths of WMAP and LFI has allowed the mitigation of both experiments’ weaknesses, and resulted in new state-of-the-art WMAP sky maps. All maps and the associated code are made publicly available through the COSMOGLOBE web page.
Cosmic birefringence is a parity-violating effect that might have rotated the plane of linearly polarized light of the cosmic microwave background (CMB) by an angle \(\beta\) since its emission. This ...has recently been measured to be non-zero at a statistical significance of \(3.6\sigma\) in the official Planck PR4 and 9-year WMAP data. In this work, we constrain \(\beta\) using the reprocessed BeyondPlanck LFI and Cosmoglobe 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 \(\beta\), and while thermal dust \(EB\) emission has been argued to be statistically non-zero, 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 \(\beta\) and the polarization miscalibration angle, \(\alpha\), of each channel, we find a best-fit value of \(\beta=0.35^{\circ}\pm0.70^{\circ}\) with LFI and WMAP data only. When including the Planck HFI PR4 maps, but fitting \(\beta\) separately for dust-dominated, \(\beta_{>70\,\mathrm{GHz}}\), and synchrotron-dominated channels, \(\beta_{\leq 70\,\mathrm{GHz}}\), we find \(\beta_{\leq 70\,\mathrm{GHz}}=0.53^{\circ}\pm0.28^\circ\). This differs from zero with a statistical significance of \(1.9\sigma\), 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 model of full-sky polarized synchrotron emission that is derived from all WMAP and Planck LFI frequency maps. The basis of this analysis is the set of end-to-end reprocessed ...Cosmoglobe Data Release 1 sky maps presented in a companion paper, which have significantly lower instrumental systematics than the legacy products from each experiment. We find that the resulting polarized synchrotron amplitude map has an average noise rms of \(3.2\,\mathrm{\mu K}\) at 30 GHz and \(2^{\circ}\) FWHM, which is 30% lower than the recently released BeyondPlanck model that included only LFI+WMAP Ka-V data, and 29% lower than the WMAP K-band map alone. The mean \(B\)-to-\(E\) power spectrum ratio is \(0.40\pm0.02\), with amplitudes consistent with those measured previously by Planck and QUIJOTE. Assuming a power law model for the synchrotron spectral energy distribution, and using the \(T\)--\(T\) plot method, we find a full-sky inverse noise-variance weighted mean of \(\beta_{\mathrm{s}}=-3.07\pm0.07\) between Cosmoglobe DR1 K-band and 30 GHz, in good agreement with previous estimates. In summary, the novel Cosmoglobe DR1 synchrotron model is both more sensitive and systematically cleaner than similar previous models, and it has a more complete error description that is defined by a set of Monte Carlo posterior samples. We believe that these products are preferable over previous Planck and WMAP products for all synchrotron-related scientific applications, including simulation, forecasting and component separation.
We implement support for a cosmological parameter estimation algorithm as proposed by Racine et al. (2016) in Commander, and quantify its computational efficiency and cost. For a semi-realistic ...simulation similar to Planck LFI 70 GHz, we find that the computational cost of producing one single sample is about 20 CPU-hours and that the typical Markov chain correlation length is \(\sim\)100 samples. The net effective cost per independent sample is \(\sim\)2 000 CPU-hours, in comparison with all low-level processing costs of 812 CPU-hours for Planck LFI and WMAP in Cosmoglobe Data Release 1. Thus, although technically possible to run already in its current state, future work should aim to reduce the effective cost per independent sample by one order of magnitude to avoid excessive runtimes, for instance through multi-grid preconditioners and/or derivative-based Markov chain sampling schemes. This work demonstrates the computational feasibility of true Bayesian cosmological parameter estimation with end-to-end error propagation for high-precision CMB experiments without likelihood approximations, but it also highlights the need for additional optimizations before it is ready for full production-level analysis.
We present Cosmoglobe Data Release 1, which implements the first joint analysis of WMAP and Planck LFI time-ordered data, processed within a single Bayesian end-to-end framework. This framework ...builds directly on a similar analysis of the LFI measurements by the BeyondPlanck collaboration, and approaches the CMB analysis challenge through Gibbs sampling of a global posterior distribution, simultaneously accounting for calibration, mapmaking, and component separation. The computational cost of producing one complete WMAP+LFI Gibbs sample is 812 CPU-hr, of which 603 CPU-hrs are spent on WMAP low-level processing; this demonstrates that end-to-end Bayesian analysis of the WMAP data is computationally feasible. We find that our WMAP posterior mean temperature sky maps and CMB temperature power spectrum are largely consistent with the official WMAP9 results. Perhaps the most notable difference is that our CMB dipole amplitude is \(3366.2 \pm 1.4\ \mathrm{\mu K}\), which is \(11\ \mathrm{\mu K}\) higher than the WMAP9 estimate and \(2.5\ {\sigma}\) higher than BeyondPlanck; however, it is in perfect agreement with the HFI-dominated Planck PR4 result. In contrast, our WMAP polarization maps differ more notably from the WMAP9 results, and in general exhibit significantly lower large-scale residuals. We attribute this to a better constrained gain and transmission imbalance model. It is particularly noteworthy that the W-band polarization sky map, which was excluded from the official WMAP cosmological analysis, for the first time appears visually consistent with the V-band sky map. Similarly, the long standing discrepancy between the WMAP K-band and LFI 30 GHz maps is finally resolved, and the difference between the two maps appears consistent with instrumental noise at high Galactic latitudes. All maps and the associated code are made publicly available through the Cosmoglobe web page.
