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Measuring the relative velocities of galaxy clusters separated by 100 Mpc Ryan Keisler U. Chicago

Measuring the relative velocities of galaxy clusters separated by 100 Mpc Ryan Keisler U. Chicago. Outline. 1. very brief overview of CMB and SPT 2. New CMB results from SPT: 3. Relative velocities of galaxy clusters. Outline. 1. very brief overview of CMB and SPT

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Measuring the relative velocities of galaxy clusters separated by 100 Mpc Ryan Keisler U. Chicago

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  1. Measuring the relative velocities of galaxy clusters separated by 100 Mpc Ryan Keisler U. Chicago

  2. Outline • 1. very brief overview of CMB and SPT • 2. New CMB results from SPT: • 3. Relative velocities of galaxy clusters

  3. Outline • 1. very brief overview of CMB and SPT • 2. New CMB results from SPT: • 3. Relative velocities of galaxy clusters

  4. What is the Cosmic Microwave Background? time The constituents of the early universe (photons, electrons, protons, dark matter, neutrinos, ...) were coupled. - gravity pulls,- radiation pressure pushes (on some of them) => oscillations

  5. What is the Cosmic Microwave Background? time Eventually the universe expands and cools such that neutral hydrogen can form. “Recombination”No more free electrons, no more Thomson scattering between photons and electrons. => Photons can travel freely, and we see them today as a blackbody with T=2.73K. The small anisotropies we see in the CMB are due to oscillations in early plasma.

  6. WMAP

  7. WMAP

  8. WMAP 1 DEGREE SMALLER SCALES.... POWER WMAP7 Figure from Larson et al.

  9. WMAP 1 DEGREE SMALLER SCALES.... LOTS TO LEARN OUT HERE. NEED BETTER ANGULAR RESOLUTION. POWER WMAP7 Figure from Larson et al.

  10. The South Pole Telescope: a mm-wave observatory • 10 meter primary mirror~1 arcminute resolution • 1st camera: 1000 bolometers.2007-2011, “SPT-SZ” • 2nd camera: 1600 bolometers. polarization-sensitive.2012-2015, “SPT-POL" • 3rd camera:15k bolometers. polarization-sensitive. 2016-? “SPT-3G” Chicago Berkeley Case Western McGill Boulder Harvard Caltech Munich Michigan Arizona ... photo by Dana Hrubes

  11. Why the South Pole? • Atmospheric transparency and stability: • Extremely dry. • High altitude ~10,500 feet. • Sun below horizon for 6 months. • Unique geographical location: • Observe the clearest views through the Galaxy, 24/365, “relentless observing” • Clean horizon. • Excellent support from existing research station. home away from home the South Pole SPT

  12. SPT as apocalypse warning system

  13. SPT-SZ 2500 deg2 Survey (6% of sky) Status: finished in Nov. 2011. Results shown today use all of this data.

  14. WMAP SPT SPT ZOOM

  15. Outline • 1. very brief overview of CMB and SPT • 2. New CMB results from SPT: • 3. Relative velocities of galaxy clusters

  16. Outline • 1. very brief overview of CMB and SPT • 2. New CMB results from SPT: • 3. Relative velocities of galaxy clusters

  17. Take the angular power spectrum of the 2500 sq. deg. SPT-SZ survey... work led by U. Chicago graduate student Kyle Story SeearXiv:1210.7231 (Story, Reichardt, Hou, RK et al.)

  18. ...and you get this. 3rdacoustic peak

  19. Comparison to previous works Planck SPT New SPT work provides: ~3X improvement over previous non-SPT works ~1.8X improvement over previous SPT work. SeearXiv:1210.7231 (Story, Reichardt, Hou, RK et al.)

  20. Angular Power Spectrum

  21. Angular Power Spectrum OLD: SPT 800 deg2 (Keisler et al 2011)

  22. Angular Power Spectrum NEW: SPT 2500 deg2 (Story et al 2012)

  23. Fitting the data to ΛCDM(and beyond) work led by Zhen Hou, UC Davis (see Hou, Reichardt, Story, Follin, RK, et al, 1212.7231)

  24. Outline • 1. very brief overview of CMB and SPT • 2. New CMB results from SPT: • 3. Relative velocities of galaxy clusters

  25. Best-fit ΛCDM CMB+foregrounds CMB

  26. ns: spectral tilt ns generically departs from ns=1 in inflationary models, because of lack of time-invariance of inflation. ns = 0.9623 ± 0.0097 (SPT+WMAP) 3.9σ preference for ns<1 ns = 0.9538 ± 0.0081 (SPT+WMAP+ H0+BAO) 5.7σ preference for ns<1 (first >5σ preference for ns<1)

  27. Outline • 1. very brief overview of CMB and SPT • 2. New CMB results from SPT: • 3. Relative velocities of galaxy clusters

  28. How many light, ν-like particle species are there? from the Particle Data Group, number of light ( ) particles that couple to the Z, • Neff = 3.62 +/- 0.48 (SPT+WMAP) • Neff = 3.71 +/- 0.35 (SPT+WMAP+H0+BAO) • Nv = 2.984 +/- 0.0082 (LEP) A much less accurate, but more generic test can be done by measuring the expansion rate of the early, radiation-dominated universe (see e.g. Steigman, Schramm, Gunn 1976). new CMB data tells us: (1.2σ higher than 3.046) (1.9σ higher than 3.046)

  29. Outline • 1. very brief overview of CMB and SPT • 2. New CMB results from SPT: • 3. Relative velocities of galaxy clusters

  30. Detecting Dark Energy using only the CMB Detection of CMB lensing in TT power spectrum breaks geometric degeneracy between curvature and dark energy.

  31. CMB lensing and the CIB 100 sq. deg. of Herschel SPIRE data on“SPT deep field” Sub-mm flux traces star-formation at z~1. RGB = 500,350,250 um

  32. CMB lensing and the CIB Smooth 500um map to ~1 degree scales (~100 com. Mpc). work led by Gil Holder

  33. CMB lensing and the CIB Smooth 500um map to ~1 degree scales (~100 com. Mpc). Add mass contours from SPT CMB lensing. work led by Gil Holder

  34. CMB lensing and the CIB Smooth 500um map to ~1 degree scales (~100 com. Mpc). Add mass contours from SPT CMB lensing. ~10σ correlation signal work led by Gil Holder

  35. CMB lensing and the CIB Smooth 500um map to ~1 degree scales (~100 com. Mpc). Add mass contours from SPT CMB lensing. ~10σ correlation signal CMB lensing is well calibrated in mass and probes how CIB traces dark matter distribution (linear bias). work led by Gil Holder

  36. Outline • 1. very brief overview of CMB and SPT • 2. New CMB results from SPT: • 3. Relative velocities of galaxy clusters

  37. matter power spectrum Hlozek et al. 1105.4887

  38. ANDREY KRAVTSOV

  39. 43 Mpc

  40. ~100 Mpc

  41. pairwise kSZ Galaxy clusters tend to fall towards each other due to mutual gravitational attraction. For a given pair, the high-z cluster tends to move towards us and vice versa. CMB photons inverse Compton scatter on cluster gas (kinetic Sunyaev-Zel’dovich Effect) => differential CMB signal proportional to relative velocity of clusters Observer

  42. pairwise kSZ Galaxy clusters tend to fall towards each other due to mutual gravitational attraction. For a given pair, the high-z cluster tends to move towards us and vice versa. CMB photons inverse Compton scatter on cluster gas (kinetic Sunyaev-Zel’dovich Effect) => differential CMB signal proportional to relative velocity of clusters Blue Shifted CMB Red Shifted CMB Observer

  43. pairwise kSZ Galaxy clusters tend to fall towards each other due to mutual gravitational attraction. For a given pair, the high-z cluster tends to move towards us and vice versa. CMB photons inverse Compton scatter on cluster gas (kinetic Sunyaev-Zel’dovich Effect) => differential CMB signal proportional to relative velocity of clusters Blue Shifted CMB Red Shifted CMB - Characterize cluster gas - 10% precision test of gravity on 100 Mpc scales? Observer

  44. ingredients Deep mm-wave data with arcminute resolution over 100s of square degrees Catalog of 100s-1000s of galaxy groups or clusters ACT ACTpol CMASS and LOWZ samples from BOSS (SDSS3) [spec-z] SPT-SZ SPT-POL SPT-3G Clusters from the Dark Energy Survey (DES), which just came online. [photo-z]

  45. ingredients Deep mm-wave data with arcminute resolution over 100s of square degrees Catalog of 100s-1000s of galaxy groups or clusters Hand et al.1203.4219 3σ detection ACT ACTpol CMASS and LOWZ samples from BOSS (SDSS3) [spec-z] RK & Schmidt1211.0668 8-40σ projected sensitivity SPT-SZ SPT-POL SPT-3G Clusters from the Dark Energy Survey (DES), which just came online. [photo-z]

  46. method Use simulated SZ skies from Sehgal et al. 0908.0540. N-body + (gas density and pressure calculated assuming hydrostatic equilibrium and a polytropic equation of state) Selected DES-like cluster sample from these simulations. M500c > 1e14 Msun/h Add realistic noise and redshift-dependent photo-z errors σz = 0.01 x exp(z/2.5) Optimally estimate pairwise kSZ signal.

  47. method Use simulated SZ skies from Sehgal et al. 0908.0540 N-body + (gas density and pressure calculated assuming hydrostatic equilibrium and a polytropic equation of state) Selected DES-like cluster sample from these simulations. M500c > 1e14 Msun/h Add realistic noise and redshift-dependent photo-z errors σz = 0.01 x exp(z/2.5) Optimally estimate pairwise kSZ signal CAVEATS: DES will select clusters on optical richness, not mass, and there will be significant scatter in mass at fixed richness. Assumed perfect knowledge of photo-z error distribution: σz.

  48. results weaker gravitational interaction (13σ) (26σ)

  49. results photo-z errors weaker gravitational interaction (8σ) (14σ)

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