README

Status of the XXL DB (June 2014)

The 100 brightest XXL clusters

The 100 brightest cluster sample is finalised.
The selection is made on the basis of count-rate measurements within a 60" arcsec aperture using a growth curve analysis.
The measurements  involved a primary sample containing the 185 brightest clusters - in terms of pipeline total count-rate - irrespective of the C1/C2 classification.

In order to quickly retrieve these objects:

• We have assigned a "quality" flag = 6 to the 100 brightest clusters as identified by the growth curve analysis (sample 2013-CS)
• We have assigned a "quality" flag = 5 to the remaining 85 measured clusters

Currently, 2013-CS contains:

•  53 clusters in XXL-N and 47 in XXL-S
  
• All clusters are C1, except one C2 in XXL-N and three C2 in XXL-S

The remaining 85 clusters are distributed as follows:

• 51 C1, 32 C2, 2 C3

IMPORTANT ADDENDUM (June 2nd, 2014)
Because five of these clusters (n0243, n0262, n0326, s0028 and s0192) are located in currenlty "bad" pointings, we have complemented the list by the five brightest ones: s0081, n0255, s0287, s0251 and s0027
Consequently, there are 105 clusters with Q=6 in the database

The details of the 2013-CS selection are available on the XXL wiki dedicated page (technical reports by N. Clerc, P. Giles and B. Maughan).

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Energy Conversion Factors

We provide below ECFs to convert the measured count-rates into fluxes for the [0.5-2] keV band.
Warning: given the mild ECF dependence on cluster spectrum or redshift, these values are sufficient for the purpose of proposal writing but not for scientific publications.

Proposed mean conversion factors (F. Pacaud - January 2013)
Assuming z=0.3, T=2 keV, Abundances =0.3 (APEC model)

• LSS [Nh=2.3 E+20]
  0.002015 MOS c/s  ==> 1e-14 erg/cm2/s   and   0.007031 PN c/s  ==> 1e-14 erg/cm2/s

• BCS [Nh=1.25 E+20]
  0.002008 MOS c/s  ==> 1e-14 erg/cm2/s   and  0.007045 PN c/s  ==> 1e-14 erg/cm2/s

NB the count-rate is for MOS1.
Hence, as a rule of thumb: a total count-rate of ~ 0.01 c/s in the [0.5-2] keV band corresponds to a flux of  ~ 1e-14 erg/s/cm2 in the same band; that is ~ 100 photons for 10 ks.

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Contact

Contact for the XXL DB (all matters): Elias.Koulouridis at cea.fr

Note

Before retrieving a cluster sample, please read:

• the general documentation on the DB,
• the description of the catalogue columns.

README archive

June 2013
December 2012
August 2011