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Science at Q band SZ/CMB models: Q-band science Mark Birkinshaw University of Bristol.

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Presentation on theme: "Science at Q band SZ/CMB models: Q-band science Mark Birkinshaw University of Bristol."— Presentation transcript:

1 Science at Q band SZ/CMB models: Q-band science Mark Birkinshaw University of Bristol

2 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol2 1. Simple observables: shape SZ effects – from inverse-Compton scattering by hot electrons on cold CMB photons. Thermal SZ effect – los amplitude  Comptonization parameter, y e, the dimensionless electron temperature weighted by the scattering optical depth

3 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol3 Simple observables: shape For a simple isothermal  model typical central value y e0  SZ effect has angular size about 3 × X-ray angular size for  ~ 0.7 (typical for rich clusters) at z = 0.2, θ c ~ 1 arcmin for rich cluster

4 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol4 Simple observables: spectrum spectrum related to gradient of CMB spectrum zero near CMB peak (about 220 GHz) flux density effect small at long λ Q

5 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol5 Simple observables: spectrum If the cluster is moving, then in the cluster frame the CMB is anisotropic. Scattering isotropizes it by an amount   e v z, giving kinematic SZE. Angular shape same as thermal SZ effect, if cluster is isothermal. Spectrum differs from thermal SZ effect, but same shape as the spectrum of primordial CMB fluctuations, so velocity information is obtained contaminated by the (lensed) primordial CMB.

6 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol6 Simple observables: kinematic SZE spectrum related to gradient of CMB spectrum no zero small compared to thermal effect at low frequency flux density effect small at long λ confused by primordial structure Q

7 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol7 2. Simple observations Simplest: single-dish radiometers/radiometer arrays. Secondary focus: single on-axis feed symmetrical dual feeds array of feeds (large focal plane) e.g., OCRA series Prime focus: single on-axis feed symmetrical dual feeds

8 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol8 Lancaster et al. (2009; in preparation) 34 highest L X clusters from ROSAT BCS (Ebeling et al. 1998) at z > 0.2 ‘fair’ sample with few biases Complete subset of 18 with Chandra data Study scaling relations: decode surveys Statistically useful cluster parameters OCRA-p on Toruń 32-m (OCRA-F now, OCRA-C possible) noise ~ 0.4 mJy [less than 1 hour/cluster] Sample studies (X-ray/optical selection)

9 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol9 Source contamination SZ effects evident in most clusters before source correction – compare cluster and trail statistics. Uncorrected: lose 20% of clusters. Corrected (GBT): lose 10% of clusters (lose 5% of trails).

10 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol10 Scaling relation: flux density/X-ray kT consistent with expected 3/2 scaling relation

11 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol11 Next step: blind survey Potential field: XMM- LSS. Survey blind in SZ, provides parallel X-ray, lensing, IR data. Too far south for Toruń: accessible to AMiBA.

12 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol12 AMiBA-13 Partially-completed AMiBA- 13 interferometer on Mauna Loa (baselines to 6.5 m). Larger antennas than in first AMiBA season. 90 GHz: would need a larger system at 30 GHz.

13 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol13 SZ effect confusion on CMB Figure from Molnar & Birkinshaw 2000 thermal SZ kinematic SZ RS effect

14 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol14 Sensitivity of radiometer Single-dish and interferometers need to use switching strategies or extra filtering. Beam-switching + position- switching, or scanning for single dishes. Multi-field differencing or fringe rate filtering for interferometers. (N > 1), but  T A doesn’t reduce with time as  -1/2 after some time: unsteady gain and T sys etc.

15 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol15 Simple observations: z dependence Angular size and separation of beams leads to redshift dependent efficiency Shape of curve shows redshift of maximum signal, long plateau. Similar for all types of observation.

16 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol16 Simple observations: interferometers SZA (2008)

17 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol17 Simple observations: interferometer sensitivity Sensitivity of interferometer N corr = number of antenna-antenna correlations used in making synthesized beam (solid angle  synth ).  source = solid angle of source. Built-in rejection of many systematic errors.

18 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol18 Simple observations: angular dynamic range restricted angular dynamic range set by baseline and antenna size good rejection of confusing radio sources (use long baselines) even tightly packed arrays trade sensitivity for resolution Abell 665 model, VLA observation available baselines

19 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol19 Simple observations: interferometer maps restricted angular dynamic range high signal/noise (long integration possible) clusters easily detectable to z  1 better for structure studies? Carlstrom et al. 1999

20 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol20 3. Simple science results Integrated SZ effects –total thermal energy content –total hot electron content SZ structures –not as sensitive as X-ray data –need for gas temperature Mass structures and relationship to lensing Radial peculiar velocity via kinematic effect

21 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol21 Simple science results: integrated SZE Total SZ flux density Thermal energy content immediately measured in redshift-independent way Virial theorem: SZ flux density should be good measure of gravitational potential energy

22 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol22 Simple science results: integrated SZE Total SZ flux density With X-ray temperature, SZ flux density measures electron count, N e (hence baryon count) and total gas mass Combine with X-ray derived mass to get f b

23 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol23 Some rough Q-band numbers These total flux densities are integrated out to the virial radius: most observations cannot go out that far. Note that the total flux densities are highly distance dependent – the detectable signals in a single beam (radiometer/interferometer) are less so because of the z- dependence of the efficiency.

24 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol24 Simple science results: SZE and lensing Weak lensing measures ellipticity field e, and so Surface mass density as a function of position can be combined with SZ effect map to give a map of f b  S RJ / 

25 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol25 Simple science results: total, gas masses Inside 250 kpc: XMM +SZ M tot = (2.0  0.1)  M  Lensing M tot = (2.7  0.9)  M  XMM+SZ M gas = (2.6  0.2)  M  CL with XMM Worrall & Birkinshaw 2003

26 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol26 z=0.68 z=0.58 z=0.73 z=0.14 z=0.29 z=0.25 Noise dominated region × pixel data from simulations clusters identified in simulations Lensing and the thermal SZ effect

27 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol27 Simple science results: v z Kinematic effect separable from thermal SZE by different spectrum Confusion with primary CMB fluctuations limits v z accuracy (typically to 150 km s -1 ) Velocity substructure in atmospheres will reduce accuracy further Statistical measure of velocity distribution of clusters as a function of redshift in samples

28 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol28 3. Simple science results: v z Need good SZ spectrum X-ray temperature Confused by CMB structure Sample   v z 2  Errors  1000 km s  so far A 2163; figure from LaRoque et al

29 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol29 3. Simple science results: cosmology Cosmological parameters –cluster-based Hubble diagram –cluster counts as function of redshift Cluster evolution physics –evolution of cluster atmospheres via cluster counts –evolution of radial velocity distribution –evolution of baryon fraction Microwave background temperature elsewhere in Universe

30 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol30 3. Simple science results: cluster distances X-ray surface brightness SZE intensity change Eliminate unknown n e to get cluster size L, and hence distance or H 0

31 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol31 Simple science results: cluster distances CL D A = 1.36  0.15 Gpc H 0 = 68  8  18 km s -1 Mpc -1 Worrall & Birkinshaw 2003

32 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol32 Simple science results: cluster Hubble diagram poor leverage for other parameters need many clusters at z > 0.5 need reduced random errors ad hoc sample systematic errors Carlstrom, Holder & Reese 2002

33 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol33 Simple science results: SZE surveys SZ-selected samples –almost mass limited and orientation independent Large area surveys –1-D interferometer surveys slow, 2-D arrays better –radiometer arrays fast, but radio source issues –bolometer arrays fast, good for multi-band work Survey in regions of existing X-ray/optical surveys –Expect SZ to be better than X-ray at high z

34 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol34 Simple science results: f B S RJ  N e T e Total SZ flux  total electron count  total baryon content. Compare with total mass (from X-ray or gravitational lensing)  baryon mass fraction Figure from Carlstrom et al b/mb/m

35 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol35 4. More complicated observables Detailed structures –Gross mass model –Clumping –Shocks and cluster substructures Detailed spectra –Temperature-dependent/other deviations from Kompaneets spectrum –CMB temperature Polarization –Multiple scatterings –Velocity term

36 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol36 Detailed structures Clumping induced by galaxy motions, minor mergers, etc. affects the SZE/X-ray relationship More extreme structures caused by major mergers, associated with shocks, cold fronts Further SZE (density/temperature-dominated) structures associated with radio sources (local heating), cooling flows, large-scale gas motions (kinematic effect). SZ effects are more relatively sensitive to outer parts of clusters than X-ray surface brightness.

37 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol37 Detailed structures J z = Clearly disturbed, shock-like substructure, filament What will SZ image look like?

38 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol38 Detailed structures Bullet cluster, Laboca (extensively filtered). High-frequency structure affected by bright point source Many other point sources; SZ effect also detected – easier in Q band, probably. (Lopez-Cruz et al.)

39 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol39 Detailed spectra Ratio of SZ effects at two different frequencies is a function of CMB temperature (with slight dependence on T e and cluster velocity) So can use SZ effect spectrum to measure CMB temperature at distant locations and over range of redshifts Test T CMB  (1 + z) Battistelli et al. (2002)

40 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol40 for low-T e gas effect is independent of T e T e > 5 keV, spectrum is noticeable function of T e non-thermal effect (high energies) gives distortion multiple scatterings give another distortion hard to measure 5 keV 15 keV Detailed spectra

41 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol41 Polarization Polarization signals are O(  z ) or O(  e ) smaller than the total intensity signals: this makes them extremely hard to measure. Interferometers help by rejecting much of the resolved signal, since some of the polarization signal has smaller angular size than  I. Still need excellent common-mode rejection to remove systematic errors in polarization.

42 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol42 5. Requirements on observations UseSize (mK)Critical issues Energetics0.50 Absolute calibration Baryon count0.50 Absolute calibration; isothermal/spherical cluster; gross model Gas structure0.50 Beamshape; confusion Mass distribution0.50 Absolute calibration; isothermal/spherical cluster Hubble diagram0.50 Absolute calibration; gross model; clumping; axial ratio selection bias

43 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol43 Requirements on observations UseSize (mK)Critical issues Blind surveys0.10 Gross model; confusion Baryon fraction evolution 0.10 Absolute calibration; isothermal/spherical cluster; gross model CMB temperature 0.10 Absolute calibration; substructure Radial velocity0.05 Absolute calibration; gross model; bandpass calibration; velocity substructure

44 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol44 Requirements on observations UseSize (mK)Critical issues Cluster formation0.02 Absolute calibration Transverse velocity 0.01 Confusion; polarization calibration

45 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol45 6. Status of SZ effects Hundreds of cluster detections –many high significance (> 10  ) detections –multi-telescope confirmations –poor interferometer maps, structures usually from X-rays Spectral measurements still rudimentary –no kinematic effect detections Preliminary blind and semi-blind surveys –a few detections (not at Q band, yet)

46 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol46 Status at the time of early ALMA 10 × more cluster detections –Planck catalogue, low-z not yet available –high-resolution surveys (AMiBA-13, SZA, SPT, APEX-SZ, etc.; Q-band selected fraction?) About 100 images with > 100 resolution elements –mostly interferometric, tailored arrays, 10 arcsec FWHM –some bolometric maps, 15 arcsec FWHM –angular dynamic range, structure indications poor A few integrated spectral measurements –Still confusion limited –Still problems with absolute calibration

47 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol47 ALMA possibilities Q band good for SZ studies –ALMA: 1 μJy in 10 arcsec FWHM over 145 arcsec primary beam in 12 hours: cluster substructure mapping with main array (loses largest scales) –quality of mosaics? –7-m antennas in compact configuration more effective on angular scales of most interest Blind surveys using ALMA band-1 not likely – wrong angular scales (OCRA-F/AMiBA/APEX-SZ/…) Fortunately, Chandra and XMM-Newton still working

48 Science at Q band 15 September 2009Mark Birkinshaw, U. Bristol48 Possible SZ unique studies Hot outflows around ionizing objects at recombination (or later) may show kinematic with little thermal SZ. SZ spectral inversion into electron distribution function – GHz range critical. Information on developing cluster velocity field. Non-thermal SZ effect in large radio sources to test equipartition (c.f., X-ray inverse-Compton studies). Leverage on relativistic electron populations?


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