The XMM Distant Cluster Project: Survey limits and Pilot

SurveyGeorg Lamer

A. Schwope, V. Hambaryan, M. Godolt (AIP)

H. Böhringer, R. Fassbender, P. Schücker, J. Santos (MPE)

C. Mullis (U Michigan), P. Rosati (ESO)

1. Extended source detection and survey sensitivity

2. X-ray redshifts

3. First results from pilot survey

Source detection pipeline

EPIC images eexpmap exposure maps

• Standard XMM-SAS detection tasks

• Similar setup as for 2XMM catalogue

eboxdetect

esplinemap background mapseboxdetect emldetect PSF fiiting

Source detection pipeline

emldetect: Fitting PSF folded with King profile

Verification of survey limitsSimulation of XMM EPIC data:

– Simulate 100 source lists with AGN logN-logS (Hasinger & Brandt 2005) + cluster logN – logS (Rosati et al. 1998)– Create simulated EPIC images in 3 x 5 energy bands (typical background, 20 ksec exposure).

Run source detection pipeline on fake data sets.

Verification of survey limits

Verification of survey limits

Verification of survey limits

Detected fraction: ~50% @ f=10-14

Spurious fraction (before visual screening)

X-ray redshifts

• Possibility of measuring redshifts from X-ray spectra?• Extracted spectra of 90 clusters with > 500 counts,

calculating grid of MEKAL models in T-z plane (Master thesis M. Godolt).

Mekalredshift=0.8kT= 4.0

X-ray redshifts

Determined 17 redshifts (mostly low T clusters @ z< 0.5)

X-ray redshifts

Newly discovered cluster @ z=0.8:

Subaru I-band

Pilot cluster survey

• Survey area: 9 deg2 at sensitivity 7x10-15 cgs

•Best sensitivity:10-15 cgs

• Detected 155 extended sources

• Optical follow up in ESO P72 / P73 (2003/2004)

Optical follow up observations

• Select high redshift cluster candidates using DSS images– Eliminate non-cluster identifications– Select DSS blank fields for R + z band imaging

with VLT FORS2

• VLT imaging in R + z bands (47 candidates)– Estimate photometric redshifts

• Spectroscopic confirmation (VLT FORS 2)

VLT imaging• Imaging observations with FORS 2:• R and z bands• Rlim > 24.5 , zlim > 23m • Determine R-z colours cluster red sequence

redshift estimate

.

z~1.2

Pilot survey: Results

Photometric (R-z) redshifts

10

XMMU J2235-2557z = 1.39

Mullis et al. 2005

Conclusions & Outlook• Survey sensitivity well described by simulations.

• Limited possibility to obtain redshifts from XMM spectra.

• Pilot survey demonstrated efficient strategy to find distant clusters

• ~ 1/4 of new XMM clusters at z > 0.5• ~ 1/4 of these have z > 1.0• XMM 2235-2557: X-ray luminous cluster at z=1.39

• Next goal: sample of 30 clusters at z >1