SZ effect and ALMA workshops Lauro Moscardini Dipartimento di Astronomia Università di Bologna, Italy IAS, Orsay, 7-8 April 2005 OAT, Trieste, 13 April 2005

Clusters of Galaxies in the Microwaves CMB+CLUSTERS Sunyaev & Zel'dovich Effect

Thermal S-Z Effect Kinetic S-Z effect  T=T s(x) y c y c =  (k B T/m e c 2 ) d  x=h p /k B T

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 H 0 ) 2) SZ observations allow to observe (in principle) all the clusters in the universe

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 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 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?) 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?)

Goals in Trieste To start a discussion on what are the best possible targets for ALMA observations: low- vs. high-redshift objects 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) 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) Are the present expertizes enough to afford the international competition? (NO)

Requirements on observations (I) Use Size (mK) Critical issues Energetics0.50 Absolute calibration Baryon count 0.50 Absolute calibration; isothermal/spherical cluster; gross model Gas structure 0.50 Beamshape; confusion Mass distribution 0.50 Absolute calibration; isothermal/spherical cluster Hubble diagram 0.50 Absolute calibration; gross model; clumping; axial ratio selection bias Birkinshaw

Requirements on observations (II) Use Size (mK) Critical issues Blind surveys 0.10 Gross model; confusion Baryon fraction evolution 0.10 Absolute calibration; isothermal/spherical cluster; gross model CMB temperature 0.10 Absolute calibration; substructure Radial velocity 0.05 Absolute calibration; gross model; bandpass calibration; velocity substructure

Requirements on observations (III) Use Size (mK) Critical issues Cluster formation 0.02 Absolute calibration Transverse velocity 0.01 Confusion; polarization calibration

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

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

Status at the time of ALMA: 2010 About 5000 cluster detections 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 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 About 50 integrated spectral measurements –Still confusion limited –Still problems with absolute calibration

Status at the time of ALMA: ALMA, 2010 Status at the time of ALMA: ALMA, 2010 ALMA band 1 suitable for SZE 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 Band 1 is not likely to be available in 2010 Blind surveys using ALMA band-1 not likely – wrong angular scales Blind surveys using ALMA band-1 not likely – wrong angular scales

Status at the time of ALMA: X-ray context: 2010 No XMM or Chandra No XMM or Chandra Constellation-X/XEUS not available Constellation-X/XEUS not available Working with archival X-ray surveys Working with archival X-ray surveys X-ray spectra of high-z clusters of relatively poor quality 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.

ALMA sensitivity in 1 minute Ghz  S (mJy) TbTbTbTb Laing

ALMA resolution Laing GHzLambda/D 180 m (arcsec)Lambda/DACA(arcsec)Resolution (arcsec)

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

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 T b – 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

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 different frequencies ALMA for SZ survey follow up

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 …..

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

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= ) 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 R vir ? I doubt… - Detection of shocks from merging events? - Detection of ICM heating events (bubbles from AGN)? - Cosmological parameters from D A (z)? Unlike turbulence, it requires relaxed clusters. S. Borgani

Turbulent ICM motions from merging Dolag et al Reduced viscosityNormal viscosity

Detecting turbulence via ICM pressure fluctuations Schuecker et al XMM mosaic: 16 pointings of ksec exposure each. Def. of pressure: I 1/2 T X

The rms pressure fluctuations P(k)  k -5/3  (dP/P) rms ~ 0.15 almost independent of the scale  In principle detectable in a clean way as fluctuations in the SZ flux decrement.

Is the turbulence ubiquitous? H-alpha coherent filamentary structures in the center of the Perseus cluster (Fabian et al. 2004)  Limit on the degree of turbulent gas motions.  Look for turbulence only in disturbed clusters?

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

~60 Clusters with L, n gas,T, z>0.3

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)?...