Radio Cosmology Tzu-Ching Chang (ASIAA) Wednesday, June 5, 2013 - - PowerPoint PPT Presentation

Radio Cosmology

Tzu-Ching Chang (ASIAA)

Wednesday, June 5, 2013

Cosmology in the Planck era

Planck (flat ΛCDM): Ho=67.95 ± 1.5 km/s/Mpc

ESA

Wednesday, June 5, 2013

Cosmology from Planck

A flat ΛCDM provides a very good fit to Planck data. The Planck calibrated ΛCDM predictions: Agree perfectly with BAO data at lower redshifts Disagree mildly (~2.5σ) with the most precise direct H0 measurements (e.g., HST Key project, Cepheids+SN). Neutrinos background detected (Neff = 3.36 ± 0.34) CMB lensing is playing an important role in the constraints, particularly on the sum of neutrino masses. Data are consistent with simplest inflation models No detected signature of primordial non-Gaussianities (fnl = 2 ± 5) Spectral index: n=0.9608 ± 0.0054 (7σ deviation from n=1).

Wednesday, June 5, 2013

Cosmology post Planck

Is it still interesting? Not end of story - we still don’t know the initial conditions, dark matter, and dark energy. Need to nail parameters with Large-Scale Structure surveys Dark energy (for wCDM, best probe at z<2). Curvature (LSS geometry probes): dk < 10-3? Sum of neutrino mass (damping of p(k)): dE < 0.01eV Non-gaussianity (scale-dependent bias): dfnl < 1?

Wednesday, June 5, 2013

Large-scale structure probes

Besides (next generation) CMB polarization, actions are in LSS. CMB: ~2D information, mode # ∝ (lmax)2 LSS redshift surveys: 3D information, mode # ∝ (kmax)3 shot noise dominates p(k) at high wavenumber k shot noise ~ 1/n_gal n_gal = 10-4 h3 Mpc-3 (SDSS, WiggleZ) n_gal = (3-5) x 10-4 h3 Mpc-3 (BOSS, HETDEX, HSC, PFS) n_gal = 10-3 h3 Mpc-3 (Euclid, LSST, SKA)

Wednesday, June 5, 2013

What can (low-freq) radio do?

Emission v.s. absorption (21-cm forests; difficult. see Hiroyuki Hirashita’s talk) Continuum emissions “thresholded”: radio continuum sources (e.g., FIRST, NVSS, EMU, MIGHTEE, WODAN surveys. Owen & Morrison 08, Condon+ 12) “non-thresholded”: radio background intensity and fluctuations (e.g. ARCADE-2, Fixsen+ 09) Line emissions (in particular, HI 21cm) “thresholded”: “SKA: billions of HI galaxies at z>1” (e.g., Verheijen+ 10, Fernandez+ 13). MeerKAT and ASKAP surveys. Gas and galaxy evolution. “non-thresholded”: 21cm Intensity Mapping (e.g., Chang+ 08, 10, Masui+ 13, Switzer+ 13) for LSS; Reionization probes.

Wednesday, June 5, 2013

Continuum Surveys

Weak Lensing by large-scale structure (Cosmic Shear) Measures both the growth factor G(z) and the geometry DA(z). Motivates many dark energy surveys: CFHT-LS, DES, Subaru- HSC, Euclid Systematics for shape measurements are challenging, in particular the PFS for ground-based optical surveys is an issue Radio interferometric has deterministic PFS and can be

• illuminating. However, dn/dz needs to be measured/modelled.

FIRST measurement (Chang+ 04); EMU, MIGHTEE, WODAN upcoming for dark energy measurements (e.g., Patel+ 10). Magnification lensing may be feasible if dn/dz is known.

Hetdex

Wednesday, June 5, 2013

Continuum Surveys

Integrated Sachs-Wolfe effect (ISW) Sensitive to gravitational potential decay on large-scales, e.g., when dark energy dominated at low-z. Requires all-sky LSS x CMB surveys (e.g., NVSS x WMAP , Nolta+ 05). Cosmic-variance limited, at most a 7σ signal. Upcoming radio surveys for modified gravity, dark energy tests (e.g., Raccanelli+08, 12; Dupe+10 review).

Granett, Neyrinck & Szapudi Wednesday, June 5, 2013

21cm emission on galaxy scales

Pilot JVLA HI survey of the COSMOS field HI morphology is a great tool for merger interaction study

0.046 0.089 0.130 0.187

R e d s h i f t

800 600 400 200

DL (Mpc)

10h 02m23s 10h 00m23s

M

z=0.029 M=1.2 x 10 M z=0.176 M=8.0 x 10 z=0.076 M=6.6 x 10 ; 6.4 x 10 M z=0.121 M=3.9 x 10 M

Fernandez+13

Wednesday, June 5, 2013

21cm Cosmology

HI 21cm radiation observable up to z~150. Probes 3D structure of the Universe, accessible via Intensity Mapping Up to 1016 modes to z~50 (Hubble/Jeans scale)3. Fundamental Physics: probes of LSS geometry and growth of structure, via Lensing, BAO, AP Astrophysics: EoR, galaxy formation & evolution Experiments Now EoR: GMRT-EoR, PAPER, LOFAR, MWA, 21CMA, EDGES, DARE LSS: GBT, CRT, CHIME SKA1 can tackle both redshift windows.

EoR

LSS

SDSS III

Tegmark & Zaldarriaga 08

Wednesday, June 5, 2013

21cm Intensity Mapping

Measure HI associated with large-scale structure instead of with galaxies (Wyithe & Loeb 08, Chang+08, Seo+10). CMB-like, but measure 3D temperature fluctuations. Low angular resolution, high spectral/redshift resolution. Provides a broad redshift window (0< z < 25) and offers an economical way for a powerful LSS survey. Confusion limited. Observational challenges: Foreground/ signal > 103. RFI issues. Initial results via cross-correlation with optical surveys are promising (Chang+10, Masui+13, Switzer+13), but needs solid auto power spectrum measurements.

Wednesday, June 5, 2013

21cm Intensity Mapping

Cross-correlating GBT HI & WiggleZ optical galaxies at z ~ 0.6-1

Masui+, GBT-HIM team, 2012

0.001 0.01 0.1 1 0.1 !(k)2 (mK) k (h Mpc-1)

15 hr 1 hr "HI bHI r = 0.43 10-3

200 hours, 41 deg2 survey at the GBT Measuring the WiggleZ fields at 800 MHz band, 0.5 < z < 1.1 Foreground subtraction using SVD in freq-freq covariance matrices, and correcting for frequency dependent beam Foreground subtraction down to factor of >100

HI brightness temperature

• n these scales at z=0.8:

ΩHI r b = (4.3 ± 1.1) x 10-4

Wednesday, June 5, 2013

Wednesday, June 5, 2013

Wednesday, June 5, 2013

21cm Intensity Mapping

Current limits on 21cm auto power spectrum and measurements on ΩHI bHI at z=0.8 using the GBT.

Switzer+ 13, the GBT-HIM team

ΩHI bHI = [0.62 +0.23 -0.15]x 10-3

Wednesday, June 5, 2013

Goal: Baryon Acoustic Oscillations

SDSS III BOSS

Anderson+12

courtesy of M. Blanton

Wednesday, June 5, 2013

CHIME/Tian-Lai/CRT/BAORadio

FFT/OMNISCOPE Telescope SKA-low and SKA-mid Telescope

BINGO BAOBAB

21cm Intensity Mapping current/future telescopes

!"#"$%&'(" ("#")*%'"+," 2345)6!"#"" '%7&"(#$%3&","#".$%*8"

GBT-HIM multi- beam

Wednesday, June 5, 2013

21cm Intensity Mapping

Forecasts on Baryon Acoustic Oscillation (BAO) distance scale.

• SUBARU !PFS, !2019+

LSST, !2021+ BINGO !? CHIME !2016+ SKA1-IM, !2019+?

Can also measure Redshift Space Distortion (RSD), which provides G(z) and DA(z)&H(z) measurements.

Wednesday, June 5, 2013

21cm tomography Lensing

21cm tomography lensing can be a powerful tool across redshifts for e.g. neutrino mass, dark energy constraints (e.g., Zahn & Zaldarriaga 06, Metcalf & White 09, etc)

ESA

NASA, ESA, Massey 2010

Wednesday, June 5, 2013

21cm tomography Lensing

Currently mostly considered for EoR era. Can be extended to both high (pre-EoR) and low (post- EoR) redshifts for SKA.

Metcalf & White 09

Wednesday, June 5, 2013

Radio-Optical synergy

Cross-correlating radio continuum sources and optical samples to obtain redshift distribution of radio sources (e.g., Newman+ 98). With dn/dz sharpens galaxy-galaxy, galaxy-shear, shear-shear, cosmic shear and magnification lensing measurements. Cross-correlating galaxy-scale 21cm emissions and/or 21cm intensity maps with photometric surveys (e.g. LSST) to help sharpen the optical photo-z accuracy and potentially extract more info. Cross-correlation measurments for BAO and RSD measurements using multi-tracer (McDonald & Seljek 08), eliminating cosmic variance.

Wednesday, June 5, 2013

What can SKA do for cosmology?

Probes Sciences Tools

Radio Tools

Geometry

curvature, dark energy, modified gravity

BAO, Gravitational lensing, RSD

HI, HI IM, continuum Growth/Gravity dark energy, modified

gravity

Gravitational lensing, RSD, ISW HI, HI IM, continuum Power Spectrum

neutrino mass non-gaussianity

Shape of Power spectrum

HI, HI IM, continuum

HI galaxy evolution

HI morphology & dynamics

HI

Wednesday, June 5, 2013

SKA Cosmology SWG

Chair: Roy Marteens (rmarteens@uwc.ac.za) A SKA cosmology white-paper is being planned: HI Surveys: Filipe Abdalla & Mario Santos Continuum surveys: Chris Blake & David Bacon (pre-)EoR Cosmology: Jonathan Pritchard Simulations: Matt Jarvis Forecasts: Pedro Ferreira Synergy with others: Keitaro Takahashi

Team Members: F. Abdalla, D. Bacon, C. Blake, T.-C. Chang, X. Chen, T.R. Choudhury, A. Cooray, P . Ferreira, S. Furlanetto, S. Inoue, M. Jarvis, U.-L. Pen, J. Pritchard, S. Prunet, M. Santos, J-L Starck, S. Zaroubi

Wednesday, June 5, 2013

What can (low-freq) radio do?

Continuum emissions “thresholded”: radio continuum sources (e.g., FIRST, NVSS, EMU, LADUMA, WODAN surveys). Cosmic Shear, Magnification lensing, ISW measure geometry and growth factor, and probe dark energy and modified gravity and dark energy. “non-thresholded”: radio background intensity and fluctuations (e.g. ARCADE-2, Fixsen+ 09) for CMB deviation from black body spectrum at low frequencies. Line emissions (in particular, HI 21cm) “thresholded”: “SKA: billions of HI galaxies at z>1” (e.g., Verheijen+ 10, Fernandez + 13). MeerkAT and ASKAP surveys. Probes gas and galaxy evolution. Merger dynamics. “non-thresholded”: 21cm Intensity Mapping (e.g., Chang+ 08, 10, Masui+ 13, Switzer+ 13) for LSS; BAO, RSD, Lensing of 21cm measure geometry, growth factor and power spectra, and probe dark energy, modified gravity, sum of neutrino masses, and non-gaussianity.

Wednesday, June 5, 2013