The main product to express cosmological constraints posed by Planck data is a Likelihood code. One of its by-product is the derived Maximum-likelihood CMB spectrum.
|NB: This is very much a scientific product, whose development status will be described in a dedicated talk at the review.|
Principles used to build Planck Likelihood
We have used an hybrid approach for the likelihood which is:
- Pixel-based at low-ell
- based on fine-grained pseudo-CL at high-ell. I.e. it uses all independent groupings of detectors at 100, 143 and 217GHz.
This allows easy “Planck-Ext” (stitching of high(er)-ell likelihoods, in particular ACT & SPT).
The Planck code, CLIK, provides a unique interface (and it allows internally to keep cross-checking with various approaches), at V4.1 now (V1 was mid-2011).
We derived from CLIK our “best” CTT, together with a basic (diagonal) error estimate, which will allow making plots & quick model checks, comparison with various sources of uncertainties comparison with the CTT derived from the CMB map(s) issued from Component Separation activities…
CLIK - The Planck C(l) LIKelihood code
This section is a copy/extract of collaboration wiki pages from which the updates will be made for major Exp.Sup. releases
[-Last modified 2012-10-10 -]
clik is a package with both a code and data files to distribute the current planck likelihood. It is available from ESA through the [PLA] under operational files, then clicking the supplementary data icon on the toolbar
Here follows a description of the last release of clik
!! Version 4.0
Main improvements for this release are the addition of
- CAMspec_v5.2dust hi-ell likelihood,
- plik_dx9_v2 hi-ell likelihood and
- an early october version of the actspt likelihood.
Partial compatibility between those likelihood has been implemented : all three share the same cib modeling and either CAMspec or plik can be this way used with actspt. CAMspec further use the same sz and szXcib modeling. plik neglect the sz and szXcib foregrounds for now (as they approximatively cancel in planck range of ells).
No update has been made on the low-ell likelihood. To recover the files (still compatible with the last version of the code) one has to retrieve clik v3.5 and use the file contained therein.
Beware that the previous CAMspec files will not work with the current release.
clik code is at version 4.0b2
- none for now.
- from 3.5
** inclusion of actspt ** removal of dependency on gel ** removal/cleanup of lot's of legacy code ** better discovery of the hdf5 version (in particular version 1.8.X compiled in pure 1.6.X compatibility mode) ** better detection of some weird python install ** plik likelihood code has been improved and is now 20times faster ** correction for the C++ boilerplate ** correction of the clik_config scripts with the addition of laking libs
** plik_dx9_v2.clik (see TOBEWRITTEN) ** CAMspec_5.2dust.clik (see TOBEWRITTEN)
- hi-ell non planck
** actspt_2012_10_08.clik (see TOBEWRITTEN)
- CAMspec has changed a lot and now include beam parameters
- actspt is new
- new easily modifiable foreground modeling module for plik.
An important note for actspt
As for the low-ell likelihood, actspt code relies on data being installed in a specific place. The file is usable as is, but will dump some data in /tmp at each initialization. If this is not a desirable behaviour, data can be dumped once and for all by following the procedure described here.
Exemple of output
We'll give here an actual exemple of use and result of an exploration
Current Best-fit CMB spectrum
This is still evolving
Cosmic Microwave background
European Space Agency