Output Product: Tomographic Cosmic Shear Correlation¶

Metadata¶

Data product name	DpdTwoPCFWLShearShear2D
Data product custodian	WLTWOPCF
Name of the Schema file	euc-le3-wl-twopcf-ShearShear2D.xsd
Last Edited for DPDD Version	1.1
Processing Element(s) creating/using the data product	Creators: LE3_2PCF_WL_ShearShear_Pipeline LE3_CM_2PCF_WL_ShearShear_Pipeline Consumers: WL-SWG
Processing function using the data product	SGS pipeline output product to be used by LE3 and SWGs
Proposed for inclusion in EAS/SAS	This product is proposed for inclusion in the SAS: Yes Motivation: the product contains the two-point shear-shear tomographic real-space correlation functions requested by the RSD document.

Data Product Elements¶

Header	object of type sys:genericHeader
Data	object of type wl2pcf:twoPCFWLShearShear2D
QualityFlags	object of type dqc:sqfPlaceHolder
Parameters	object of type ppr:genericKeyValueParameters

Detailed Description of the Data Product¶

This product contains the tomographic cosmic shear 2PCF.

This output product is a fits file (see le3.wl.2pcf.output.shearshear2d in the following FITS descriptors).

Extra metadata associated to the FITS container are the following:

SpatialCoverage a description of the spatial footprint [optional, cot:spatialFootprint],
CatalogSelection: describing the selection in the input catalogues [optional, up to 1 element]
- CatalogFileName: the name of the input catalogue [sys:dataFileName]
- CatalogSHE: type of input catalogue [string among “BFD”, “KSB”, “LensMC”,”MomentsML”,”REGAUSS”,”MER_PHZ”, “OTHER” ]
- Selection: selection associated to catalogue [string]
- CatalogUse: for which use case the catalog is employed (=[“ShearShear”]) [string among “PosPos”, “PosShear”, “ShearShear”]
- CatalogInfo: whether position or shear information is used in this catalogue [string among “Pos”, “Shear”] (=[“Shear”])
- CatalogOrder: order associated to catalogue for reporting (e.g. BIN_ID1)[int32]

The fits file contains:

a primary array containing important computation parameters as keywords,
binary tables in the next HDUs with cosmic shear 2-PCF for specific redshift bins.

Primary Array¶

This fits table is expected to contain the following keywords in primary HDU, characterizing the important parameters of the product:

HDU PRIMARY: header
	Name	Description	Value
Keywords	SIMPLE		logical
	BITPIX		integer
	NAXIS		integer
	EXTEND		logical
	THMIN	Min of angular range	double
	THMAX	Max of angular range	double
	OATH	Open Angle threshold	double
	THUNIT	Unit of theta	string
	BINSCALE	lin or log bins	string
	COORDSYS	cartesian or spherical	string
	SHE_SOFT	Where the input catalogue is coming from (if SHE catalogue used)	string
	SHE_SEL	ID of selection made (e.g. tomographic redshifts, stellar mass)	string
	SOFTNAME		string
	SOFTVERS		string
	BLINDING	Flag that identifies products that have been blinded for scientific analysis	string

THMIN: minimal angular value chosen for spatial binning [DoubleKeyword]
THMAX: maximal angular value chosen for spatial binning [DoubleKeyword]
OATH: maximal open angle value used for the approximation [DoubleKeyword]
THUNIT: unit of spatial distance [StringKeyword]
BINSCALE: if linear or logarithmic scales are used for output [StringKeyword]
COORDSYS: if spherical or cartesian computation of distances [StringKeyword]
SHE_SOFT: which SHE catalogue used [StringKeyword]
SHE_SEL: selection for shear catalogue [StringKeyword]
SOFTNAME: name of software used for 2PCF [StringKeyword]
SOFTVERS: version of software used for 2PCF [StringKeyword]

Table (HDU=1…)¶

The following keywords are added to the header of the HDUs:

HDU SHEARSHEAR2D_2PCF_n: header
	Name	Description	Value
Keywords	XTENSION		string
	BITPIX		integer
	NAXIS		integer
	NAXIS1		integer
	NAXIS2		integer
	PCOUNT		integer
	GCOUNT		integer
	TFIELDS		integer
	TTYPE1		string
	TFORM1		string
	TTYPE2		string
	TFORM2		string
	TTYPE3		string
	TFORM3		string
	TTYPE4		string
	TFORM4		string
	TTYPE5		string
	TFORM5		string
	TTYPE6		string
	TFORM6		string
	TTYPE7		string
	TFORM7		string
	TTYPE8		string
	TFORM8		string
	EXTNAME		string
	BIN_ID1	First Bin in Correl	integer
	BIN_ID2	Second Bin in Correl	integer

HDU SHEARSHEAR2D_2PCF_n: 8 columns table
	Name	Description	Unit	Format
Columns	THETA		NA	FITS D
	XI_P		NA	FITS D
	XI_M		NA	FITS D
	XI_X		NA	FITS D
	WEIGHT		NA	FITS D
	SQRT_D		NA	FITS D
	SQRT_DCOR		NA	FITS D
	NPAIR		NA	FITS D

BIN_ID1: bin for first catalog [IntegerKeyword]
BIN_ID2: bin for second catalog [IntegerKeyword]
EXTNAME: “SHEARSHEAR2D_2PCF”

and the columns are:

THETA: mean angular separation in the bin [D, float64]
XI_P: cosmic shear 2PCF \(\xi_+\) [D, float64]
XI_M: cosmic shear 2PCF \(\xi_-\) [D, float64]
XI_X: cosmic shear 2PCF \(\xi_x\) [D, float64]
WEIGHT: total weight for the bin [D, float64]
SQRT_D: Poisson error associated to the bin [D, float64]
SQRT_DCOR: Poisson error associated to the bin, down-weighted by the ratio of number of galaxy pairs by the number of nodes [D, float64].
N_PAIR: Number of pairs [D, float64]

The correlation functions are defined as:

\[\begin{split}\xi_\pm &=\langle \epsilon_t \epsilon_t\rangle \pm \langle \epsilon_x \epsilon_x\rangle\\ \xi_x &= \langle \epsilon_t \epsilon_x \rangle\end{split}\]

with \(\epsilon_t\) tangential component and \(\epsilon_x\) cross component of ellipticity.

Note

Under discussion is the possibility in the future of having as first HDU a summary table with information on the binning for 2PCF tables (HDU>2):

THETA: angular separation (center of spatial bin) [D, float64]
MIN_THETA: minimal angular separation in the bin [D, float64]
MAX_THETA: maximal angular separation in the bin [D, float64]

and in the second hdu a summary table to allow fast access to the HDU corresponding to a particular bin combination:

BIN_ID1: bin for first catalog [J, int32]
BIN_ID2: bin for second catalog [J, int32]
HDU: HDU index [J, int32]