cmb
8 posts
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GNILC dust templates: impact of the zero-level offset fix
The PySM 3 GNILC dust templates were regenerated after fixing the NumPy indexing bug of issue #281 that left the zero-level offset in the intensity input. This notebook compares the released 2023 templates with the regenerated ones: intensity zero level, polarization fraction, TT/EE/BB spectra, and the mean intensity check of issue #226. A dedicated section answers why the polarization fraction distribution differs from fig. 5 of Planck 2018 XII: the fix places the templates at the low-offset convention of that figure, and the residual is sky region and resolution.
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GNILC dust zero-level offset with the Lenz et al. 2017 low-velocity HI map
The original zero-level measurement used the full HI4PI column density, which includes high-velocity clouds that carry no dust. Redoing it with the Lenz et al. 2017 low-velocity map proposed in the feedback on PySM issue #281 shifts the intercept by only +0.001 MJy/sr: the offset is confirmed at about 0.126 MJy/sr. Includes the residual map requested in the discussion: the low-valued bump is a southern, high-column population that does not track the >90 km/s gas, with hemispheres differing in FIR per unit column but agreeing on the intercept.
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Measuring the zero-level offset of the GNILC dust intensity map with HI4PI
The CIB monopole was never subtracted from the GNILC dust input of the PySM d9/d10/d11 templates because of a NumPy indexing bug; this notebook measures the real zero-level offset of that map from the HI4PI HI correlation.
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PySM: produce CAR output at the smoothing stage
PySM 3 only builds HEALPix skies. Here is how to produce CAR pixelization output at the smoothing stage with a single spherical harmonic transform, and a validation against the smooth-then-reproject route.
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healpy 1.20.0b1 beta — harmonic_ud_grade for artifact-safe map downgrading
pip install --pre healpy==1.20.0b1 harmonicudgrade changes map NSIDE through spherical-harmonic transforms with pixel-window and beam transfer corrections following Eq. 1 of Planck 2015 X (arXiv:1502.01588).
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healpy harmonic_ud_grade vs skytools change_resolution: A Comparison
A comparison of healpy.harmonic_ud_grade and skytools.change_resolution for HEALPix map resolution changes, highlighting API differences, beam/pixel-window support, direct alm input, and agreement levels.
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BK18 added to Panexp model suite and new WebSky radio source models in PySM 3.4.1
Following up on my previous post about Panexp model suite simulations, there have been several important updates: BK18 Simulation Now Available
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New simulations of the Panexp model suite for Planck and WMAP
Following up on my recent post about PySM models for Galactic emission, I have recently executed three new simulations of the Panexp model suite: