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Results from ACBAR and XCS

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Results from ACBAR and XCS

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  1. RESUltS & LESSONs from the ACBAR (SZ) and XCS (X-ray) Cluster Surveys Kathy Romer (University of Sussex) on behalf of THE ACBAR and XCS CollaborationSThanks to the following PEOPLE FOR unpublished figures:ACBAR: Laura VAlkoneNXCS: Nicola MehRtens, Ben Hoyle, Mark Hosmer, Ed lloyd Davies

  2. Some of the unpublished XCS figures have been removed for the on line version of this talk. This is because the plots were preliminary and should not be used without appropriate cautionary remarks. Since the meeting, we have made a lot of progress and newer versions are available. If you are interested, you are welcome to contact the speaker [romer@sussex.ac.uk]

  3. Results from ACBAR and XCS ACBAR • Detection of thermal SZ signal as a decrement, increment and null • Spectral subtraction of CMB noise • SZ flux predicts mass better than X-ray flux • Resolved SZ at z<0.1 • Detection of “Blind SZ clusters” XCS • Large samples of clusters and groups with measured temperatures. • Our initial L-T relation • The impact of scaling relations on cosmology • Mass calibrations for optical cluster surveys • The latest from our highest z cluster

  4. Results from ACBAR and XCS ACBAR • Detection of thermal SZ signal as a decrement, increment and null • Spectral subtraction of CMB noise • SZ flux predicts mass better than X-ray flux • Resolved SZ at z<0.1 • Detection of “Blind SZ clusters” XCS • Large samples of clusters and groups with measured temperatures. • Our initial L-T relation • The impact of scaling relations on cosmology • Mass calibrations for optical cluster surveys • The latest from our highest z cluster

  5. Lessons from ACBAR and XCS ACBAR • Bolometer maps are not the same as “direct images” • Some clusters have no detectable SZ signal (why?) • It is possible to make 2D SZ maps of clusters using bolometer arrays • It is easy to be too ambitious • Joint X-ray-SZ analysis is computationally difficult XCS • The importance of selection functions • You can manage [to get Tx zx] with a few hundred counts • We need more synthetic clusters to test physics • You can automate cluster analysis (spectral and spatial) • Better to exploit the XMM archive than new surveys

  6. Lessons from ACBAR and XCS ACBAR • Bolometer maps are not the same as “direct images” • Some clusters have no detectable SZ signal (why?) • It is possible to make 2D SZ maps of clusters using bolometer arrays • It is easy to be too ambitious • Joint X-ray-SZ analysis is computationally difficult XCS • The importance of selection functions • You can manage [to get Tx zx] with a few hundred counts • We need more synthetic clusters to test physics • You can automate cluster analysis (spectral and spatial) • Better to exploit the XMM archive than new surveys

  7. Result 1 from Acbar: The Detection of SZ Thermal Signal as Decrement, Increment and Null • Abell S1063, z=0.35 • 1st SZ maps of this cluster • 150 hrs of observations

  8. Result 1 from Acbar: The Detection of SZ Thermal Signal as Decrement, Increment and Null • Abell 3827, z=0.10 • 1st SZ maps of this cluster • 199 hrs of observations

  9. Result 1 from Acbar: The Detection of SZ Thermal Signal as Decrement, Increment and Null • Bullet Cluster, z=0.29 • 1st time this cluster has been mapped above and below the null simultaneously • 162 hrs of observations

  10. Result 2 from Acbar: Spectral Subtraction of CMB Noise • Bullet cluster at 3 frequencies and after spectral subtraction (bottom)

  11. Result 2 from Acbar: Spectral Subtraction of CMB Noise • Zoom into Rayleigh-Jeans images of the three clusters: • Bullet (snr=23) • AS1063 (snr=17) • A3827 (snr=31) • Approx ratio of X-ray luminosities: 1 to 1 to 0.2 • Approx ratio of X-ray temperatures: 1 to 1 to 0.5

  12. Result 2 from Acbar: Spectral Subtraction of CMB Noise • The mathematical formulism to do the subtraction is in the appendix of our paper, if you want to do it too.

  13. Result 2 from Acbar: Spectral Subtraction of CMB Noise • The mathematical formulism to do the subtraction is in the appendix of our paper, if you want to do it too.

  14. Result 3 from Acbar: SZ FLUX predicts Mass better than X-ray Flux (in merging clusters) • Using total-Y value to predict the X-ray temperature is better than using X-ray flux.

  15. Result 3 from Acbar: SZ FLUX predicts Mass better than X-ray Flux (in merging clusters) • Using total-Y value to predict the X-ray temperature is better than using X-ray flux.

  16. Result 3 from Acbar: SZ FLUX predicts Mass better than X-ray Flux (in merging clusters) • Using total-Y value to predict the X-ray temperature is better than using X-ray flux • this is good news for cosmology from SZ surveys • But watch out for nH

  17. Result 4 from Acbar: RESOLVED SZ emission at z<0.1 SKIPPING THIS • A3266, z=0.06 • the X-ray Luminosity is 1/12th of the Bullet cluster’s • A3921, z=0.09 • the X-ray Luminosity is 1/20th of the Bullet cluster’s

  18. Result 5 from Acbar: Detection of “Blind SZ clusters” SKIPPING THIS • We have dozens of candidates in the deep CMB survey regions • One of our best has associated extended thermal X-ray emission (right) and an optical galaxy over density (both at z=0.6)

  19. Result 1 from XCS: Large samples of clusters and groups with measured temperaTures • Right: extended sources with at least 300 counts. • Top: Tx>2 keV (193 so far) • Bot: Tx<2keV (98 so far) • RED: redshifts come from the X-ray fits • GREEN: redshifts come from optical photometry • BLUE: redshifts come from optical spectroscopy

  20. The number of clusters with Tx will jump up soon (2,000 more XMM observations were processed last month) Red: previous generation of XCS. Blue: new data added in June Result 1 from XCS: Large samples of clusters and groups with measured temperaTureS

  21. Result 1 from XCS: Large samples of clusters and groups with measured temperaTureS • Why should SZ observers care about this? • Because you can’t do cosmology without a reliable mass proxy • Because to do your mass calibrations, you need more Y-T data. • Why not use XCS clusters are SZ targets in your required mass and redshift ranges. The Y-T data available so far is a great start, but we need a lot more data to do cosmology. (Don’t we?)

  22. Result 2 from XCS: A fresh look at Cluster Scaling relations • XCS compared to existing studies: • More clusters • Larger redshift range • Similar (or better) mass range • Well understood selection function XCS Luminosity-Temperature relation (no selection function has been applied; we are working on that at the moment) [plot removed, ask author for ino]

  23. Result 2 from XCS: A fresh look at Cluster Scaling relations • Why should SZ observers care about this? • The slope of the Lx-Tx departs from self-similarity and tells us there is extra physics. • The same extra physics will mess with your SZ maps. • Hopefully by studying the Lx-Tx in detail, we’ll be able to help you get cosmology out of your SZ surveys.

  24. Result 3 from XCS: The impact of unknown scaling relations on cluster cosmology • The number of clusters in a given survey is strongly dependent on the underlying scaling relations, their scatter and evolution • Assume the wrong relations and you will get the wrong cosmology • see 0802.4462 for more info Forecast of cluster numbers in the XCS area (selection function applied). All with the same M-T and the same cosmology. Blue and orange: with scatter Blue and green: with evolution

  25. Result 3 from XCS: The impact of unknown scaling relations on cluster cosmology • The number of clusters in a given survey is strongly dependent on the underlying scaling relations, their scatter and evolution • Assume the wrong relations and you will get the wrong cosmology • see Sahlen et al 2009 (0802.4462) for details

  26. Result 3 from XCS: The impact of unknown scaling relations on cluster cosmology • Why should SZ observers care about this? • The same statement apply to SZ surveys as to X-ray surveys: • Assume the wrong relations and you will get the wrong cosmology

  27. Result 4 from XCS: towards Mass calibration for optical cluster surveys SKIPPING THIS • Large area optical surveys for clusters have the potential to constrain Dark Energy parameters. But they need external mass calibration. • We have produced optical to X-ray mass scaling relations and have shown that you can measure masses from optical data (albeit with scatter) • TOP: X-ray clusters (XCS and ROSAT): the mass is scaled from Lx • Bottom: XCS clusters with photometry and Tx

  28. Result 4 from XCS: towards Mass calibration for optical cluster surveys SKIPPING THIS • Why should SZ observers care about this? • The optical clusters surveys are coming up fast. • They cover more area. • They get redshifts for free….

  29. Result 5 from XCS: the latest on our highest redhift cluster (XCS XMMJ2215 @z=1.45) SKIPPING THIS • Featured in 4 papers already, more to come: • 0904.0006 • 0903.1731 • 0708.3258 • 0606075 • We have lots of spectra, more time awarded. • We have HST, Chandra and Spitzer data

  30. Result 5 from XCS: the latest on our highest redhift cluster (XCS XMMJ2215 @z=1.45) SKIPPING THIS • Why should SZ observers care about this? • you don’t really! • Marginal connection via • radio (AGN) contamination • impact of galaxies on the cluster scaling relations.

  31. Lessons from ACBAR and XCS ACBAR • Bolometer maps are not the same as “direct images” • Some clusters have no detectable SZ signal (why?) • It is possible to make 2D SZ maps of clusters using bolometer arrays • It is easy to be too ambitious • Joint X-ray-SZ analysis is computationally difficult XCS • The importance of selection functions • You can manage [to get Tx zx] with a few hundred counts • We need more synthetic clusters to test physics • You can automate cluster analysis (spectral and spatial) • Better to exploit the XMM archive than new surveys

  32. Lesson 1 from ACBAR: bolometer Maps are not the same as direct images • The raw data are heavily processed to remove chopper synchronous offsets. • Certain modes are suppressed by the scanning and reduction strategies. AS1063 at 150 GHz before offset removal

  33. Lesson 1 from ACBAR: bolometer Maps are not the same as direct images • The raw data are heavily processed to remove chopper synchronous offsets. • Certain modes are suppressed by the scanning and reduction strategies. AS1063 at 150 GHz after offset removal

  34. Lesson 1 from ACBAR: bolometer Maps are not the same as direct images • Why should SZ cosmologists care? • There are complexities in the selection function that are hard (impossible?) to model AS1063 at 150 GHz after offset removal

  35. Lesson 2 from Acbar: Some X-ray Clusters have no SZ signal (Why?) • A3667 is a similar redshift and X-ray luminosity to A3226, but we couldn’t detect it however hard we tried. • Same thing when we compare A3158 with A3226 (same redshift, similar luminosity). • Radio contamination does not seem to be the reason

  36. Lesson 2 from Acbar: Some X-ray Clusters have no SZ signal (Why?) • A3667 is a similar redshift and X-ray luminosity to A3226, but we couldn’t detect it however hard we tried. • Same thing when we compare A3158 with A3226 (same redshift, similar luminosity). • Radio contamination does not seem to be the reason.

  37. Lesson 2 from Acbar: Some X-ray Clusters have no SZ signal (Why?) • A3667 is a similar redshift and X-ray luminosity to A3226, but we couldn’t detect it however hard we tried. • Same thing when we compare A3158 with A3226 (same redshift, similar luminosity). • Radio contamination does not seem to be the reason. A3667 at 4.8GHz A3158 at 4.8GHz

  38. Lesson 2 from Acbar: Some X-ray Clusters have no SZ signal (Why?) • A3667 is a similar redshift and X-ray luminosity to A3226, but we couldn’t detect it however hard we tried. • Same thing when we compare A3158 with A3226 (same redshift, similar luminosity). • Radio contamination does not seem to be the reason. A3112 at 4.8GHz

  39. Lesson 2 from Acbar: Some X-ray Clusters have no SZ signal (Why?) • Why should SZ cosmologists care? • There are complexities in the selection function that are hard (impossible?) to model A3112 at 4.8GHz

  40. Lessons from ACBAR and XCS ACBAR • Bolometer maps are not the same as “direct images” • Some clusters have no detectable SZ signal (why?) • It is possible to make 2D SZ maps of clusters using bolometer arrays • It is easy to be too ambitious • Joint X-ray-SZ analysis is computationally difficult XCS • The importance of selection functions • You can manage [to get Tx zx] with a few hundred counts • We need more synthetic clusters to test physics • You can automate cluster analysis (spectral and spatial) • Better to exploit the XMM archive than new surveys

  41. Lessons from ACBAR and XCS ACBAR • Bolometer maps are not the same as “direct images” • Some clusters have no detectable SZ signal (why?) • It is possible to make 2D SZ maps of clusters using bolometer arrays • It is easy to be too ambitious • Joint X-ray-SZ analysis is computationally difficult XCS • The importance of selection functions • You can manage [to get Tx zx] with a few hundred counts • We need more synthetic clusters to test physics • You can automate cluster analysis (spectral and spatial) • Better to exploit the XMM archive than new surveys

  42. Lesson 1 from XCS: the importance of selection functions • The cluster population in your catalogue (X-ray, SZ or optical) is very sensitive to the selection function • Without selection functions you can’t do cosmology • The scaling relation results you derive from your catalogue is very sensitive to the selection function • Without scaling relations, you can’t do cosmology….

  43. Lesson 1 from XCS: the importance of selection functions • The cluster population in your catalogue (X-ray, SZ or optical) is very sensitive to the selection function • Without selection functions you can’t do cosmology • The scaling relation results you derive from your catalogue is very sensitive to the selection function • Without scaling relations, you can’t do cosmology…. CLEF (synthetic clusters) L-T relation before application of the XCS selection function

  44. Lesson 1 from XCS: the importance of selection functions • The cluster population in your catalogue (X-ray, SZ or optical) is very sensitive to the selection function • Without selection functions you can’t do cosmology • The scaling relation results you derive from your catalogue is very sensitive to the selection function • Without scaling relations, you can’t do cosmology…. • C CLEF (synthetic clusters) L-T relation after application of the XCS selection function

  45. Lesson 1 from XCS: the importance of selection functions • The cluster population in your catalogue (X-ray, SZ or optical) is very sensitive to the selection function • Without selection functions you can’t do cosmology • The scaling relation results you derive from your catalogue is very sensitive to the selection function • Without scaling relations, you can’t do cosmology…. Pacaud et al. have shown that it is possible to correct the measured L-T if the selection function is known.

  46. Lesson 1 from XCS: the importance of selection functions • The cluster population in your catalogue (X-ray, SZ or optical) is very sensitive to the selection function • Without selection functions you can’t do cosmology • The scaling relation results you derive from your catalogue is very sensitive to the selection function • Without scaling relations, you can’t do cosmology….

  47. Lesson 1 from XCS: the importance of selection functions • Why should SZ cosmologists care? • There are complexities in the selection function that are hard (impossible?) to model • These complexities include our current lack of knowledge of cluster physics (especially at high z)

  48. Lesson 1 from XCS: the importance of selection functions SKIPPING THIS • Aside: the referee on our cosmology paper was very worried about the impact of unknown cluster properties on the selection function. • So we’ve tested it as much as we can with CLEF and by and large our approach is OK (but we need better synthetic samples to be sure). XCS Detection efficiency for synthetic clusters from the CLEF simulation, as function of substructure and redshift 48

  49. Lesson 2 from XCS: you can manage [to get tx and zx] with only a few hundred counts • Its hard to measure accurate X-ray temperatures for hot clusters. • But most XCS clusters are <5keV and 300 counts is OK • We can even measured pretty good X-ray redshifts! Predicted X-ray temperature errors for 8, 5, 3, 2, 1.5 keV

  50. Lesson 2 from XCS: you can manage [to get tx and zx] with only a few hundred counts • Its hard to measure accurate X-ray temperatures for hot clusters. • But most XCS clusters are <5keV and 300 counts is OK • We can even measured pretty good X-ray redshifts! XCS temperature function

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