Introduction
============

The "Cluster of Galaxies Data Products" is currenly described for the following Processing Functions:

* :ref:`PF-DET-CL`: Galaxy cluster detection [**Priority 2**]

PF DET-CL shall provide, according to the requirements R-LE3-PRD-F-200 and R-LE3-PRD-F-201 of the RSD:
 - the catalogs of cluster candidates detected from the galaxy photometric catalog and the probability distribution functions of photometric redshifts from the spectroscopic catalog.
 - for each cluster candidate, the following quantities and uncertainties: central position (RA, DEC), redshift (spectroscopic whenever available, or photometric), characteristic size, mass-proxies such as richness, stellar mass, luminosity, signal to noise, velocity dispersion, number of galaxies with spectroscopic redshift available.
 - the cluster candidate members to be identified in the galaxy catalog through a membership probability

.. image:: flowchart-detcl.png

* :ref:`PF-RICH-CL`: Richness of galaxy clusters [**Priority 3**]

PF-RICH-CL shall provide, according to the requirements R-LE3-PRD-F-210 and R-LE3-PRD-F-211 of the RSD:
 - the refined estimate of the richness of the cluster candidates
 - the photometric membership probability of belonging to any of the cluster candidates. The photometric membership probability will be used by Z-CL,  LF-CL, MF-CL, PROF-CL.

* :ref:`PF-SEL-CL`: Selection Function of the the clusters detection [**Priority 3**]

PF-SEL-CL shall provide, according to R-LE3-PRD-F-204, 205, 207 and 208:
 - some subsamples selected according to a range of parameters of the cluster catalogues
 - the selection function corresponding to the photometric cluster catalogue provided by each cluster detection algorithm as a function of redshift, richness or signal to noise, for all locations on the celestial sphere. The cluster selection function shall provide an estimate of the probability that a cluster of a given richness, had it existed in the Universe, would have been observed with Euclid
 - a random un-clustered catalogue that matches the angular and redshift selection of clusters and contains at least 50 times more objects than the cluster catalogue

* :ref:`PF-CAT-CL`: Selection Function of the the clusters detection [**Priority 3**]

CAT-SEL-CL shall provide, according to R-LE3-PRD-F-201 & 202:
  - The catalogs of clusters identified by all the algorithms of DET-CL. These shall include the following quantities and associated uncertainties for each cluster candidate:

* from DET-CL: central position in projected coordinates (right ascension and declination), signal-to-noise of the detection, richness or/and amplitude, detection redshift, detection size;
* from Z-CL: refined redshifts (photometric and, if available, spectroscopic and a combination of the two);
* from SIG-CL: velocity dispersion;
* from PROF-CL: refined size estimate, refined center estimate ;
* from RICH-CL: refined richness estimates (several estimates at different angular sizes); from LMF-CL: integrated luminosities and stellar masses (several estimates at the same angular sizes used to estimate the richness);
* from COMB-CL: weak lensing mass estimates (several estimates at the same angular sizes used to estimate the richness)

  - CAT-CL should provide an algorithm that performs cross-identification of clusters found by different detection algorithms. In the catalogue, cross-identifications shall be flagged.

.. More detailed charts showing the products issued from the PF requirements and the intermediate product outputs, are presented in the DET-CL introduction page.

In the perspective of the participation of "Clusters" PF into SC8, a global "Clusters" Data Model is being prepared. Here is its DPDD : ref:`PF-CLUSTER-CL` . This description is open for discussion/corrections.