suzanne staggs (princeton) rencontres de blois, 1 june 2011 the atacama cosmology telescope (act):...

Suzanne Staggs (Princeton) Rencontres de Blois, 1 June 2011

The Atacama Cosmology Telescope (ACT):

Still More Cosmology from the Cosmic Microwave

Background

ACT• 6m off-axis Gregorian telescope • Located at 5200 m (0.5 mm PWV)• 3 arrays of 1024 TES bolometers each• 148 GHz, 218 GHz, 277 GHz• 18 institutions, 4 continents, PI = Lyman Page

42’

148 GHz:1.4’ resolution30 K-rt(s)f3db ~ 84 Hz


The CMB Power Spectrum




mh2, bh2,,

R2

Matter density: mh2

Baryon density:

bh2Dark energy:

Optical depth: Primordial amplitude at

k0=0.002 Mpc-1R2

Image courtesy WMAP science team circa 2007



mh2, bh2,,

R2

ns, running of ns, Neff, Yp, lensing, 8 (SZ), point sources

Matter density: mh2

Baryon density:

bh2Dark energy:

Optical depth: Primordial amplitude at

k0=0.002 Mpc-1R2

Primordial scalar index: ns

Running of ns: dln ns/ dln k# Relativistic species: Neff

Primordial He abundance: Yp Gravitational lensing: AL

Cluster SZ contributions: 8 Point sources (radio, IR, clustered and Poisson)

The Sunyaev Zeldovich (SZ) Effect


The CMB scatters off electrons in the hot gas of clusters of galaxies, parameterized by the Compton y:

where Te and Ne describe the temperature and number density of the electrons in a cluster.

The Sunyaev Zeldovich Effect: Clusters in the CMB Power Spectrum


•Low mass clusters and other hot gas are not resolved but impact the power spectrum

•B3000 = 7+- 3 K2, ~ independent of template

•Models are required to connect to 8 -- consistent with 8 =0.75 +-0.05

•(cf 8 =0.80 +-0.04 from WMAP7+BAO+SN, and 8=0.77+-0.03 from Xray clusters – Vikhlinin et al 2009)

At l = 3000, the power spectrum has multiple contributions: primordial fluctuations, the SZ contribution, and sources (radio and dusty galaxies).

Lensing at 3 in CMB Power Spectrum

Parameterize such that AL=1 is predicted lensing; AL=0 is nonlensing. Find: AL = 1.3+-0.5 at 68% CL

Lensed

Unlensed

Higher order statistics are better -- but lensing is seen even in the power spectrum!


The Damping Tail of the CMB Power Spectrum


ns, running of ns, Neff, Yp

Primordial scalar index: ns

Running of ns: dln ns/ dln k# Relativistic species: Neff

Primordial He abundance: Yp

Can also help break the degeneracy between ns and r, the ratio of scalar to tensor fluctuations

The Damping Tail of the CMB Power Spectrum


Running of ns: dln ns/ dln k; # Relativistic species: Neff; Primordial He abundance:

Yp

Testing Inflation with the Power Spectra

Ratio of tensor to scalar fluctuation amplitudes, r, varies with the inflation energy scale

Polarization B-modes will constrain r better soon!


Primordial power spectrum P(k) described as power law in the wavevector k.

Canonical values shown as crosshairs: ns=1 (flat spectrum), dns/d ln k = 0ns = 0.962 +- 0.013 3 different from

1

(ACT +WMAP)

Particle Physics in the Power Spectra

•Neff = number of relativistic particle species,

•Neff affects when matter density begins to dominate energy budget & suppresses early acoustic oscillations in CMB

•Nominally 3 neutrinos -- data consistent.

•CMB data alone now bound Neff from above!

•Recent measurements:

•Neff = 5.3 +- 1.3 (ACT +WMAP)

•Neff = 3.85 +-0.62 (SPT +WMAP – Keisler et al 2011)

•Neff= 4.34+-0.88 (WMAP + BAO, Komatsu et al 2010)

•Neff = 3.77+0.67 (WMAP + optical data, Reid et al 2010)


•The 2.984 +- 0.008 neutrino species measured from the width of the Z boson contribute 11% of the energy density at the time of last scattering!

Nuclear Physics in the Power Spectra

•Yp = fraction of primordial helium

•BBN prediction as dotted line

•More helium --> smaller electron density --> more Silk damping

•No-helium universe ruled out at 6 --> independent confirmation of BBN!


Note – more primordial Helium decreases the number of electrons at recombination, increasing the photon diffusion length more damping.

Beyond the Power SpectrumThe Sunyaev Zeldovich (SZ) Effect:

ACT Cluster Yield (to date)Figure courtesy of T. Marriage

•50 clusters (148 GHz only -- southern 2008 data and preliminary SDSS Stripe 82 2009 data)•37 SZ-discovered (not only ACT)•Median z = 0.45•Analysis still underway!


Marriage et al 2010b

Optical confirmations of first 23 clusters: Menanteau et al, 2010 (using SOAR and NTT)

STACKING to find SZ from groups and clusters associated with luminous red galaxies from SDSS Stripe 82.

Hand et al, 2011, 1101.1951

“Both data sets are rich and have multiple components, with possible correlations among them, that we will be sorting out as the data and our understanding improve.”

Beyond the Power Spectrum:ACT SZ Measurement of 1013-1014 Msun

Groups/Clusters

1) Y from Tsz (sims)2) M from:•Weak lensing (Reyes et al 2008)•Halo bias (Seljak et al 2005)•Halo bias (Reid et al 2010)


SZ effect ~ independent of z.But: cluster cosmology requires the Y-M relation!

Das et al, 2011, 1103.2124 (accepted for PRL)

Beyond the Power Spectrum:First Detection of Gravitational Lensing from the CMB Alone


Typical 3’ shift, but convergence spectrum peaks at l = 50: large & small scales coupled (non Gaussian)!Simulated difference between

lensed and unlensed CMB in 10ox10o patch

Data from ACT 4pt function

Sherwin et al, 2011, 1105.0419 (accepted for PRL)

Extending the Power Spectrum:Dark Energy from the CMB Alone


The lensing probes the universe at z~0.2, breaking the dark energy/matter/curvature degeneracy in the CMB power spectrum alone.

Hlozek et al, 2011, 1105.4887

Under the Power Spectrum:Fitting ACT data for the Primordial P(k) in bins


PRIMORDIAL P(k)

P(k, z=0)

The Future for ACT

ACTPOL: 4x More Sensitive than MBAC• Larger field of view (5x)• More detectors at 150 GHz (feedhorn coupled)• Improved noise performance• Colder bath temperature

• More clusters, cosmology with clusters• Improved parameters from improved spectra (more, deeper

maps)• Cross-correlation of lensing convergence spectrum with LSS

tracers – probing the growth rate of structure• Polarization capability: ACTPOL (funded) • Measuring early dark energy, w, and constraining the sum of the

neutrino masses

M. Niemack et al. 2010 (1006.5049)


Forecast m to 0.07 eV(not all systematics modeled yet)

THE END

ACT 2008 data papers &

• Hincks et al 2010 ‘Beam Profiles and First SZ Cluster Maps’, ApJS 191, 423

• Fowler et al 2010 ‘A Measurement of the 600< ell <8000 Cosmic Microwave Background Power Spectrum at 148 GHz’, ApJ 722,1148

• Swetz et al 2011 ‘The Receiver and Instrumentation’, 1007.0290, accepted ApJ

• Marriage et al 2011 ‘Extragalactic Sources at 148 GHz in the 2008 Survey’, ApJ 731, 100

• Menanteau et al 2010 ‘Physical Properties and Purity of a Galaxy Cluster Sample Selected via the Sunyaev-Zel'dovich Effect’, ApJ 723, 1523

• Hajian et al 2010 ‘Calibration with WMAP Using Cross-Correlations’, 1009.0777

• Das et al 2011 ‘A Measurement of the CMB Power Spectrum at 148 and 218 GHz from the 2008 Southern Survey’, ApJ 729, 62

• Dunkley et al 2011 ‘Cosmological Parameters from the 2008 Power Spectra’, 1009.0866

• Sehgal et al 2011 ‘Cosmology from Galaxy Clusters Detected via the Sunyaev-Zel'dovich Effect,’ ApJ 732, 44.

• Hajian et al 2011 ‘Correlations in the (Sub)millimeter background from ACTxBLAST’, 1101.1517

• Hand et al 2011 ‘Detection of Sunyaev-Zel'dovich Decrement in Groups and Clusters Associated with Luminous Red Galaxies, 1101.1951

• Das et al 2011 ‘Detection of the Power Spectrum of CMB Lensing,’ accepted PRL, 1103.2124

• Sherwin et al 2011 ‘Evidence for dark energy from the cosmic microwave background alone using the Atacama CosmologyTelescope lensing measurements,’ accepted PRL, 1105.0419

• Hlozek et al 2011 ‘A Measurement of the Primordial Power Spectrum,’ 1105.4887

suzanne staggs (princeton) rencontres de blois, 1 june 2011 the atacama cosmology telescope (act):...

Documents

n s running of n s

dln n s dln

power spectrum b

y p slide

poisson slide

primordial fluctuations

y p primordial scalar

primordial amplitude