MACS first results

1
MACS first results

• Alastair Edge
• and Harald Ebeling (Hawaii),
• Ian Smail, Nathan Courtney, Graham Smith,
  Jean-Paul Kneib, Richard Wilman
• and many more

2
What is MACS?

• ROSAT All-Sky Survey selected massive clusters
• Fx(0.1-2.4keV)gt10-12erg s-1 cm-2
• bgt20o and decgt-40 (mostly)
• zgt0.3
• Confirmed with CCD imaging

3
Basic selection

• Kissing many frogs
• Lots of UH2.2m nights
• And spectroscopy on UH2.2m, CFHT, Keck, NTT and
  Gemini

4
Results so far

• 142 clusters (including selection at declt-40)
• An increase of gt15x over EMSS
• Decrease in space density of the most luminous
  clusters

5
Have cluster, will follow-up

• First stage UH2.2m VRI imaging (Nathan Courtneys
  thesis)
• Second stage 4-8m multi-object spectroscopy
• Third stage deep VRIz Subaru imaging
• Then Chandra, VLA, UKIRT, HST imaging and S-Z

6
VRI imaging results

• Colour vs redshift trends in BCG and
  Colour-Magnitude relations as expected
• BCG absolute magnitude scales with X-ray
  luminosity
• C-M trends place zgt1.7 limit on formation of
  member galaxies

7
Multi-object spectroscopy

• UH get access to Keck, CFHT and Gemini and each
  has been used to measure cluster member redshifts
• So far 35-40 clusters have been observed and
  typically 25-35 cluster redshifts have been
  measured in each
• Velocity dispersions of 800-1500 km/s
• Several very disturbed systems

8
Chandra imaging

• We have 49 Chandra observations of MACS clusters
  to date
• These observations show a very wide variety of
  morphologies
• Temperatures being determined now

9
HST imaging

• We were awarded 42 orbits in Cycle 12 (PI
  Ebeling) for 12 zgt0.5 clusters
• Lensing the primary focus of the science case
• Some very exciting results so far

10
S-Z follow-up

• Carlstrom group has detected all but one zgt0.5
  MACS clusters (La Roque etal. 2003)
• Motivation of declt-40 observations based on S-Z
  observations from the South Pole

11
Cooling flows

• A number of BCGs show Ha line emission
• At zgt0.5 Ha moves into J-band
• Got UKIRT spectroscopy
• One cluster stands out and we have detected
  CO(3-2) for it

12
Where next?

• Writing the paper presenting the sample!
• Just failed to get HST snapshot imaging in last
  cycle
• More X-ray data
• 8m spectroscopy of strongly lensed background
  galaxies

13
Beyond MACS

• ROSAT survey doesnt go much deeper than the
  10-12 erg s-1 cm-2 so we need another X-ray
  sample to select from
• XMM-Newton will eventually survey around
  100sq.deg.
• We need dedicated large area X-ray survey (DUET)

14
Conclusions

• MACS will be a resource for cluster studies for
  many years to come
• Watch this space.