galaxies and galaxy clusters at mm wavelengths: the view from the south pole telescope

Galaxies and galaxy clusters at mm wavelengths:

the view from the South Pole Telescope

Gil Holder

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On one side: CMB/SZ, “fundamental physics”

on the other side: BLAST, “astrophysics”

Outline• Small scale CMB anisotropy

– Detection of secondary anisotropies– Limits on thermal SZ, kinetic SZ

Lueker et al, Hall et al (both submitted)

• Galaxies– “point sources” in SPT maps– Dusty and/or synchroton-dominated galaxies– a new class of dusty galaxies?

Vieira et al (submitted)

Zoom in on 2 mm map~ 4 deg2 of actual data

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Detecting the SZ Power Spectrum

SPT Measured Points(model + Gaussian scatter)

• after removing bright sources, there is still small-scale contamination from residual sources

•Primary CMB looks right

• Poisson Point-sources as expected

10 K-arcmin point sources

guess at SZ power spectrum (8=0.8)

primary C

MB

150GHz

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Detecting the SZ Power Spectrum

SPT Measured Points(model + Gaussian scatter)

10 K-arcmin point sources

Hall et al. (2009, arxiv:0912.4315): we report tSZ + kSZ + clustered point-source power of 10K2 at=150GHz and l=3000

primary C

MB

150GHz

What happened to all the thermal SZ power?

Clustering of Point Sources

• Radio and IR/submm sources presumably trace the large scale matter fluctuations

• Back of the envelope:– Power spectrum

contribution: mean T2 x projected clustering amplitude

– Arcminute scales: few Mpc has clustering ~1 in 3D, divide by number of independent cells along line of sight => 1e-3

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The importance of multiple frequencies

Frequency scaling of Dusty Galaxy Background

9Scaling of Poisson power with frequency

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Hall et al 2010

10

First detection of clustered point source power from CIB sources in the mm bands

Hall et al 2010

Frequency scaling of Dusty Galaxy Backgrounds

Single-SED model assumes all galaxies have same rest-frame properties (T=34 K, =2) spread over a broad range in redshift (peaking at z=2)

Removing dusty galaxies

• Models suggest that nearly all of the residual power (both Poisson and clustered) is from high-z dusty galaxies

• To remove these, SPT constructed a map that is T150-xT220– Subtraction factor is tuned to minimize small scale power [no

noise bias in power spectrum]

– New map has all of tSZ, but has subtracted some fraction of CMB+kSZ

– Subtraction is imperfect: unknown and non-unique spectral behaviour of dusty sources

Temperature scaling

• Radio sources look a lot like CMB

• Dusty galaxies are much brighter at higher frequencies Frequency

(GHz)

Dusty galaxies (z=0,2,5)

Radio galaxies

dTcmb

Power Spectrum: Dusty Galaxy Contributions Largely Subtracted

Direct subtraction of (220 GHz map)/3 from 150 GHz map to

remove dusty galaxies

Power Spectrum: Dusty Galaxy Contributions Subtracted

Best fit 150 GHz power:

tSZ+0.46*kSZ=4.2 1.5 uK2

tSZ

kSZ

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What does the low SZ power mean?

• If we assume the fiducial tSZ model is correct (and some fiducial kSZ template), we find 8 = 0.746 ± 0.017

Compare to 8 = 0.794 ± 0.027 for WMAP5 + ACBAR + QUaD

• Allowing the best estimate (from theory considerations) 50% uncertainty on tSZ model amplitude gives 8 = 0.779 ± 0.025

Not Much Room for kSZ• Thermal SZ alone is

already a bit low• Using X-ray-based

profiles and WMAP chains, cl 8

16

• covariances between parameters conspire, in particular , h

• SPT analysis (Lueker et al.) used semi-analytic gas model, with cl 8

11 in CMB

chains

Best fit 150 GHz power:

tSZ+0.46*kSZ=4.2 ±1.5 uK2

Where does SZ Power Come From?

• Broad range in z

• Extends to low mass (relative to SPT SZ-detected clusters)

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From Shaw et al 09

Rough SPT mass limit for detection

Non-Gaussianity of statistics

d2cl /(dlnM dz) at ell~2500

SPT Galaxies at 150 & 220 GHz

Distribution of Spectral Indices

sources cleanly separate into two populations

synchrotron

dust

AGN counts

AGN counts as predicted

at high flux

source counts

dominated by

synchrotron-

dominated

sources

at the low flux end of the 1.4 mm band where dusty

sources become

dominant

150 GHz

220 GHz

dust source counts

red = Lagacheblue = Pearson

BCS image of a dusty SPT source with an IRAS counterpart

r band 5σ = 24.65 AB mag

i band 5σ = 24.35 AB mag

S1.4 = 14 mJyS2.0 = 8 mJy

BCS image of a dusty SPT source without any counterpart

r band 5σ = 24.65 AB mag

i band 5σ = 24.35 AB mag

S1.4 = 17 mJyS2.0 = 5 mJy

dust source countsWITH IRAS SOURCES REMOVED

red = Lagacheblue = Pearson

Comparison to Negrello et al. 2007

Current Followup Campaign

• ATCA: 3 mm 4 detections after two weeks of observing

• SMA: 1.4 mm detections for ~ 10 or our most northern sources

• Spitzer: 3.6 + 4.5 um observations down to 1 uJy (data taken, fully reduced)

• NOAO SOAR 4m: R,I,J,K observations done, data being reduced

• Gemini-S: spectroscopy for z>4 candidates in queue

• BCS griz ~ 60 square degrees in the can

Interferometric Follow-up

• ATCA at 90 GHz– Hard frequency

– Good location (Australia)

• SMA at 220 GHz– Easy frequency– Terrible location (Mauna Kea)

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SMG 10S1.4mm=21 mJy

SPT,SMA,IRAC,Gemini

SMG 03S1.4mm=37 mJy

BCS

Summary• SPT has measured the small-scale CMB

power spectrum, detecting secondaries– SZ power may be a bit low (or matter power spectrum is a

bit low)Hall et al, Lueker et al (submitted)

• interesting population of galaxies at mm wavelengths– Either nearby galaxies with very cold dust or extremely

bright high-z galaxies– Lensed?– Discovered because of large area (~100 deg^2) searched

compared to existing catalogsVieira et al (submitted)

IR/Submm Source Clustering

• Mean Tcmb~104 uK at 500 um (FIRAS)

• Clustering amplitude 10-3

• => few 105 uK2

• BLAST: 106 uK2

• Mean Tcmb~50 uK at 150 GHz (FIRAS, number counts)

• => few uK2

• We do actually have a clustering model

BLAST: Viero et al 2009

• Extrapolate ARCADE results to 150 GHz: 5uK

• Extrapolate source models: less than 1 uK

– => << 1uK2 clustering power at 150 GHz

• Aside: ARCADE extrapolation to 30 GHz: T~200 uK

• 30 GHz clustering power could be >50 uK2

• However: widely agree that ARCADE results are hard to reconcile with known populations

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Radio Source Clustering

Fixsen et al 2009