Anthony Challinor (Astrophysics Group, Cavendish Lab, Cambridge, UK),
Gayoung Chon (LBL, Berkeley, USA),
Stéphane Colombi (Institut d'Astrophysique de Paris, France),
Eric Hivon (IPAC/Caltech, USA & IAP),
Simon Prunet (Univ. of Toronto, Canada & IAP),
István Szapudi (Institute for Astronomy, Hawaii, USA).
This Fortran90 program measures the 2 point auto (or cross-) correlation functions w(θ) and the angular auto- (or cross-) power spectra C(ℓ) from one or (two) sky map(s) of Stokes parameters (intensity I and linear polarisation Q and U). It is based on the fast Spherical Harmonic Transforms allowed by isolatitude pixelisations such as HEALPix [for Npix pixels over the whole sky, and a C(ℓ) computed up to ℓ=ℓmax, PolSpice complexity scales like Npix1/2 ℓmax2 instead of Npix ℓmax2]. It corrects for the effects of the masks and can deal with inhomogeneous weights given to the pixels of the map. In the case of polarised data, the mixing of the E and B modes due to the cut sky and pixel weights can be corrected for to provide an unbiased estimate of the "magnetic" (B) component of the polarisation power spectrum. Most of the code is parallelized for shared memory (SMP) architecture using OpenMP.
Main input files are the HEALPix sky maps to analyse, and the pixel masks and weights if any. Those can be either in FITS binary format or in
Planck-HFI internal I/O format/DMC database objects.
Main input parameters are file names, and various options such as (gaussian) beam window correction, pixel window correction, noise substraction, angular range of the correlation functions and apodization angle.
Output w(θ) and C(ℓ) are plain text or FITS files or DMC objects.
empirical TT C(ℓ) covariance matrix can be produced.
The maps can be either in RING or NESTED scheme. They can be in full-sky or cut-sky format.
In the case of cross-correlation, the 2 maps being analyzed should have the same coordinates
but can have been observed with different beams, and can have different pixel sizes (ie, different Nside, since v03-03-01).
The mask and weighting scheme applied to each map should have the same Nside as the map to which they apply;
they can be different for each map but should spatially overlap.
A different pixel mask can be applied to the intensity and polarization components of the map(s).
The best fit monopole and dipole can be regressed out of unmasked pixels before the analysis (since version 02-05-08)
IDL routines (src/ispice.pro, src/read_spice.pro) are provided to run PolSpice and read its results from IDL or its free clone GDL.
A python routine (src/ispice.py) is provided to run PolSpice from python.
Standard Healpix/IDL and healpy tools can be used to visualize PolSpice outputs.
For instance, IDL (bin_llcl.pro) and python (bin_llcl.py) routines are available to bin the output C(ℓ), as discussed here.
If linked with Healpix 3.10 or above, arbitrary extensions and columns can be read from the input FITS files.
More details on the theory can be found in
Spice C(ℓ) Estimator:
Chon et al, 2004, MNRAS 350, 914
Szapudi, Prunet & Colombi, 2001, ApJ 548, 115
C(ℓ) Covariance Matrix:
Efstathiou, 2004, MNRAS 349, 603
Challinor & Chon, 2005, MNRAS 360, 509
Other cut sky C(ℓ) estimators:
MASTER: Hivon et al, 2002, ApJ 567, 2
POKER: Ponthieu et al, 2011, A&A 535, A90
Examples of PolSpice application to data analysis
BICEP 2yr data analysis: paper (Chiang et al, 2009; arXiv:0906.1181), data product
CMBPol Mission Concept Study: Prospects for polarized foreground removal (Dunkley et al, 2008; arXiv:0811.3915)
Planck 2013 and 2015 frequency maps (auto and cross) angular power spectra
Gravitational Lensing & Dark Matter:
Dark Energy Survey data analysis: Cross-correlation of gravitational lensing from DES Science Verification data with SPT and Planck lensing
Neutrino & High Energy Particule Science:
IceCube data analysis: Observation of Anisotropy in the Arrival Directions of Galactic Cosmic Rays at Multiple Angular Scales with IceCube
Requirements for installation:
Fortran90 compiler (some are available for free for Unix, Linux, MacOSX and Windows, such as gfortran and g95)
recent HEALPix Fortran90 library (2.10 or more required, 3.20 or more recommended)
cfitsio library (also required by HEALPix, which needs cfitsio 3.20 or more)
Problems with PolSpice?
Note 1: versions v02-08-00 and v03-00-01 require the flag -ffree-line-length-0 flag when compiled with gfortran
README in html
Questions (and answers) on PolSpice usage and its results
|README||Documentation||2017-08-29||latest release documentation (also included in release tarball)|
|HISTORY||History||2017-08-29||code modification history (also included in release tarball)|
|v03-03-02||tar.gz archive||2017-04-07|| previous release:|
- kernelsfileout now outputs apodization induced kernel even for Temperature only analysis (see FAQ for details)
|v03-03-01||tar.gz archive||2017-02-21|| old release:|
- support for cross-correlation of maps with discrepant pixel sizes (Nside)
- introduction of python routine bin_llcl.py to bin output C(ℓ)
|v03-02-00||tar.gz archive||2016-08-09||old release:|
* bug correction in reading of polarized cut-sky FITS maps (thanks to Tilman Troester);
* improvements to read_spice.pro:
- documentation header,
- deal with 9-column ASCII outputs;
* improvements to ispice.py by Kyle Story:
- added corfile argument to output angular correlation functions,
- more efficient search for spice executable.
|v03-01-06||tar.gz archive||2015-10-12||old release:|
- when 2 polarized maps are cross-correlated, 9 or 6 spectra are computed, depending on symmetric_cl setting
- introduced tolerance keyword for E/B decoupling
- bugs correction in keyword parsing
- new python wrapper (ispice.py)
- bugs correction and improvements in IDL wrapper (ispice.pro)
- add SUBDIPOL in output FITS header
|v03-00-03||tar.gz archive||2015-03-02||old release:|
- fixes bug with un-initialized map variables (addresses Nside<=32 problem described on cosmocoffee)
- all lines are now shorter than 132 characters (default gfortran limit)
HEALPix 3.20 or more recommended.
|v03-00-01||tar.gz archive||2014-04-14||old release:|
- added listmapfiles*_* and listmapweights*_* options to allow linear combination of input maps
- computes correctly cross-power spectrum of 2 maps when the first one is masked or weighted (maskfile and/or weightfile are set), and the second one is not (maskfile2 and weightfile2 not set)
- turned-off monopole and dipole removal on (Q,U) maps in mask (and weight) free cases
- correct default value of extramap* in example parameter file (--help option)
See Note 1 below
|v02-09-00||tar.gz archive||2013-03-29||old release:|
makes use of CFTISIO Extended File Name features available in HEALPix 3.10 and above, allowing the reading of arbitrary FITS extensions and columns in beam_file*, mapfile* and maskfile*.
HEALPix 3.10 or more recommended.