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SZ effect and ALMA workshops

Dive into the realm of cosmic clusters with the Sunyaev-Zel'dovich Effect and ALMA workshops in Italy, focusing on galaxy clusters in the microwave spectrum. Explore the impact of SZ observations at high angular resolution and key frequency bands for studies in mm/submm windows. Understand the significance of SZ and X-ray observations, ALMA capabilities, and the evolving landscape of cluster detections and imaging techniques. Engage in discussions about future strategies for SZ observations and potential enhancements in the field.

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SZ effect and ALMA workshops

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  1. SZ effect and ALMA workshops Lauro Moscardini Dipartimento di Astronomia Università di Bologna, Italy lauro.moscardini@unibo.it IAS, Orsay, 7-8 April 2005 OAT, Trieste, 13 April 2005

  2. CMB+CLUSTERS Sunyaev & Zel'dovich Effect Clusters of Galaxiesin the Microwaves

  3. Kinetic S-Z effect Sunyaev & Zel'dovich Effect Thermal S-Z Effect T=T s(x) yc yc = (k BT/mec2) d x=hp/kBT

  4. Sunyaev & Zel'dovich Effect 1) SZ effect depends on the projection of n along the line of sight 2) SZ effect is independent of redshift 1) Combination of SZ and X-ray observations gives important information on the gas structure ; Combination of SZ and X-ray observations provide information on the cluster Distance (estimate of H0) 2) SZ observations allow to observe (in principle) all the clusters in the universe

  5. Goals in Paris • To start discussions on what will remain to be done on the SZ effect at the beginning of 2012 when ALMA will be fully operational • To investigate the importance of observations of the SZ effect at high angular resolution • To define what are the key frequency bands for SZ studies in the mm/submm windows, in particular, are there crucial bands which are not in the baseline project? (band 1?)

  6. Goals in Trieste • To start a discussion on what are the best possible targets for ALMA observations: low- vs. high-redshift objects • Is it possible to create a common strategy between different groups in terms of proposals? (YES) • Are the present expertizes enough to afford the international competition? (NO)

  7. Requirements on observations (I) Birkinshaw

  8. Requirements on observations (II)

  9. Status at the time of ALMA: 2005 Birkinshaw Current status • About 100 cluster detections • high significance (> 10) detections • multi-telescope confirmations • interferometer maps, structures usually from X-rays • Spectral measurements still rudimentary • no kinematic effect detections • Preliminary blind and semi-blind surveys • a few detections

  10. A 3266: z = 0.06 • VIPER +ACBAR • Images at 150, 220, 275 GHz, 5 arcmin FWHM • Remove CMB to leave thermal SZE (bottom right) Gómez et al. 2003

  11. Status at the time of ALMA: 2010 • About 5000 cluster detections • Most from Planck catalogue, low-z • 10% from high-resolution surveys (AMiBA, SZA, BOLOCAM, etc.) • About 100 images with > 100 resolution elements • Mostly interferometric, tailored arrays, 10 arcsec FWHM • Some bolometric maps, 15 arcsec FWHM • About 50 integrated spectral measurements • Still confusion limited • Still problems with absolute calibration

  12. Status at the time of ALMA: ALMA, 2010 • ALMA band 1 suitable for SZE • 1 microJy in 10 arcsec FWHM over 145 arcsec primary beam in 12 hours • Cluster substructure mapping (loses largest scales) • Quality of mosaics still uncertain • Band 1 is not likely to be available in 2010 • Blind surveys using ALMA band-1 not likely – wrong angular scales

  13. Status at the time of ALMA: X-ray context: 2010 • No XMM or Chandra • Constellation-X/XEUS not available • Working with archival X-ray surveys • X-ray spectra of high-z clusters of relatively poor quality Optical/IR survey follow-up in SZE, or order of follow-ups reversed: SZE before X-ray.

  14. Discussion • Collaboration on a single region? • Problems with redshift! • Archives for data • Which structures you can see with ALMA: imaging, i.e. pressure! remind that typical scales are from 3 to 5 arcsec and spectra are between 90-350 GHz (+)

  15. Conclusions (Laing) • ALMA performance with ACA and total power: • emphasize compact configuration • different frequencies • Simulations of physics (see Kitayama & Kneissl) • what might we expect to see – need S or Tb – plus spatial scales, preferably images • not just rich clusters: small scales are good, so think about cluster substructures, galaxies, groups, protoclusters, etc… • Simulations of ALMA response • ALMA visibility • add errors, reconstruct, work out how long

  16. Conclusions (ctd) • Importance of multiple frequencies: • separate tSZ, kSZ and rSZ • foreground (synchrotron, dust, …) • for cavities, need syncrothron, SZ, thermal, IC components.. • absence of NEW X-ray imaging • complementary of ALMA and small interferometric arrays & bolometers: same resolution @ different frequencies • ALMA for SZ survey follow up

  17. Conclusions (ctd) • ALMA band 1: • ability to sample larger spatial scales: sensitivity • Band 2 less important • make a case for ALMA enhancements (NOT YET) • Lots of interesting sources for SZ: • substructures • cavities, bubbles, shocks, turbolence, etc • high-redshift clusters • …..

  18. Discussion in Trieste • What is changing for SZ observations when ALMA is used? (see e.g. talks by Testi and Andreani) • Which are the best targets? • Low-redshift clusters: properties of ICM (see e.g. talk by Borgani) • High-redshift clusters: global properties (see e.g. talk by Tozzi)

  19. S. Borgani To be better understood 1. Refine estimates of exposure time and feasibility. 2. How ubiquitous is the turbulent ICM? 3. Go for medium-distant clusters (z=0.3-0.5) or for very local ones (z~0.1) ? 4. What else these high sensitivity SZ observations can be useful for? - Detection of shocks from diffuse accretion at Rvir? I doubt… - Detection of shocks from merging events? - Detection of ICM heating events (bubbles from AGN)? - Cosmological parameters from DA(z)? Unlike turbulence, it requires relaxed clusters.

  20. Turbulent ICM motions from merging Dolag et al. 2005 Reduced viscosity Normal viscosity

  21. Detecting turbulence via ICM pressure fluctuations Schuecker et al. 2004 XMM mosaic: 16 pointings of 10 - 40 ksec exposure each. Def. of pressure: I1/2TX

  22. The physics of the ICM (and the nature of the non-gravitational energy budget) can be studied in low-z, bright clusters where the X-ray information dominates. Why an SZ follow up of high-z, X-ray clusters? X-ray information is rapidly lost at high z: low SB in external region (difficult to recover the T Gradient), lost of information on T (and P) structure in the inner region due to low S/N redshifting of the spectral band. SZ observations can help in recovering the information lost from the X-ray band. P. Tozzi

  23. ~60 Clusters with L, ngas,T, Z @ z>0.3

  24. Cosmological impact of SZ follow-up of X-ray, high-z clusters: Understanding the P (T) structure of the ICM in the inner regions The impact of massive merger on the thermodynamics structure of the ICM (increasing relevance at high-z) Improve cosmological tests like baryonic fraction affected by T gradients Understanding the nature of self-similarity break (AGN heating, SN heating)? ...

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