SZ with ALMA & ACA: a user s perspective. Tetsu Kitayama Toho University, Japan

Transcription

1 SZ with ALMA & ACA: a user s perspective Tetsu Kitayama Toho University, Japan

2 Collaborators Daisuke Iono Univ. of Tokyo Ryohei Kawabe NAOJ Kotaro Kohno Univ. of Tokyo Eiichiro Komatsu Univ. of Texas Hiroshi Matsuo NAOJ Yasushi Suto Univ. of Tokyo Shigehisa Takakuwa ASIAA Motokazu Takizawa Yamagata Univ. Takahiro Tsutsumi NAOJ Kenkichi Yamada Toho Univ. Kohji Yoshikawa Univ. of Tsukuba

3 Outline 1. Impacts of high-resolution SZE observations 2. SZE mapping by interferometers 3. ALMA/ACA imaging simulations

4 An example: RX J at z= , 580 kpc + point source (4mJy) Color: R-band Contours: ROSAT kev (Schindler et al. 1997) The most X-ray luminous cluster known 150GHz (Komatsu et al. 2001; TK+04) NOBA on Nobeyama 45m 13 beam + 15 smoothing 1σ=0.7 mjy/beam Contours: Chandra kev (Allen+02)

5 An example: RX J at z= , 580 kpc + point source (4mJy) 90GHz (Mason et al. 2010) MUSTANG on GBT 100m 9 beam + 4 smoothing 1σ=0.3 mjy/beam Contours: 1-5σSZE 150GHz (Komatsu et al. 2001; TK+04) NOBA on Nobeyama 45m 13 beam + 15 smoothing 1σ=0.7 mjy/beam Contours: Chandra kev (Allen+02)

6 Further evidences of merger in RX J kev Suzaku kev spectrum 150 ks (Ota et al. 2008) Combined with spatially resolved Chandra kev data, Contours: Radio halo Color: XMM Contours: Lensing mass Grey scale: VLT (Gitti et al. 2007) (Miranda et al. 2008) kt excess = kev (X-ray only) cf. kt excess =28.5 ± 7.3 kev (SZE+Chandra) *Mach number~2.1 (γ=5/3) V preshock ~3900 km/s V postshock ~1600 km/s

7 1E (Bullet cluster) at z=0.3 shock Projected T e Chandra kev 500 ksec (Markevitch & Vikhlinin 07) 1 =270 kpc 1E at z=0.30 Color: X-ray (collisional gas) Contours: weak lensing (Clowe; Mastropietro & Burkert 08) Mach number ~ 3.0 (γ=5/3) V preshock ~4700 km/s V postshock ~1600 km/s * Temperature is inferred from E<7 kev band

8 Implications If clusters indeed host V shock ~4000 km/s E kin > ergs! How general? Compatible with ΛCDM? (e.g., Hayashi & White 2006; Springel & Farrar 2007; Lee & Komatsu 2010) Impacts on ICM physics Non-equilibrium gas, particle acceleration, etc. * V is not directly measured, only inferred from n e, T e. Accurate measurements of T and V & more sample by hard X-rays & SZE

9 ASTRO-H (=NEXT, launch: 2014) ASTRO-H Next generation X-ray satellite 1. Micro-calorimeter kev, ΔE=5eV, FOV=3, Δθ=1.3 gas velocity, temperature from lines 2. Soft X-ray CCD kev, ΔE=150eV, FOV=38, Δθ=1.3 wide area mapping Suzaku (6m, 1.7t) 14m 2.4t 3. Hard X-ray imager 5-80 kev ΔE<2keV, FOV=9, Δθ=1.7 non-thermal, very hot gas 4. Soft γray detector kev no imaging capability Spatial resolution >1 cf. Nustar (2012-) : 43 IXO: hard X-ray >30

10 More high resolution SZE images! Typical size of hot regions (e.g., Bullet, RX J1347) ~100 kpc ~20 at z=0.3, ~10 at z>1 cannot be resolved in hard X-rays in near future. Higher chance of major mergers at z>0.5 For spherical clusters, T e (r) and n e (r) can be measured by SZE + X-ray imaging data, without spatially resolved X-ray spectroscopy. etc. MUSTANG, CARMA should be very powerful. What about ALMA/ACA?

11 Source 1 Source 2 Some basics of interferometers 1) Correlated signals among separate telescopes reduce systematics x [rad] <<1 2) Separate source positions phase difference b

12 Interferometers measure Visibility 2D Fourier transformation of intensity on the sky Spatial frequencies b/λ Intensity on the sky phase Good u-v coverage information on various spatial scales (separation of point sources & SZE) Short baseline or large λ large angular size

13 Beam and image In practice, the entire (u,v) space cannot be covered u-v sampling function dirty beam dirty image (convolved) S(u,v) Uniform Top-hat Gaussian B(x,y) Delta Sinc Gaussian Final I(x,y) is usually deconvolved with B(x,y) & convolved with Gaussian

14 Dirty beam and dirty image S(u,v) N. Marcelino, NAASC memo #104

15 SZE with interferometers First SZE image by interferometers: A2218 (Jones et al. 1993) Ryle 13m 8, 15GHz FWHM 2, FOV x 12 hours long-baseline data point sources Short-baseline data after subtraction of sources extended SZE

16 OVRO/BIMA RX J1347 z=0.45 Carlstrom et al. (2002) 6m m 38 clusters

17 SZE images by interferometers A1914 XMMU J2235 A2146 Cl J1415 AMI, 15GHz 3.7m m 8 (AMI collaboration 2006, 2011) SZA, 31 & 90GHz 3.5m 8 + more ready! (Culverhouse et al. 2010) AMiBA, 100GHz 60cm 7 (Wu et al. 2009)

18 ALMA & ACA ACA (Atacama Compact Arrays) 7m 12 & 12mSD 4 Lower resol. Image of full operation Altitude 5000m Main arrays 12m 50 Higher resolutions (16 for early operation)

19 ALMA: u-v coverage SD Dec = hr 7m 12 12m 50 Compact configuration # of baselines = N(N-1)/2

20 ALMA bands

21 FOV ~ λ/ D ~ FWHM of single dish FWHM ~λ/ b max Field-of-views of ALMA 2 = 0.5 Mpc at z=0.3 = 0.7 Mpc at z=0.5 = 1 Mpc at z=1 Bullet cluster at z=0.3 (Mastropietro & Burkert 08) 7m 12m 90GHz (band 3) 225GHz (band 6) 350 GHz (band 7)

22 Foregrounds/contaminations Spectra of Galactic foregrounds ( Others: synchrotron radio halos dusty galaxies (similar spectra to the left) extragalactic radio sources atmosphere etc.

23 ALMA/ACA imaging simulations at 90GHz Inputs: (1) Gaussian (2) Simulated merging clusters (SPH or mesh) + point sources 12m m 12 + SD(12m) 4 Use MIRIAD (Multi channel Image Reconstruction, Image Analysis and Display) software. * Checked to agree with CASA (ALMA s official software) in representative cases.

24 (1) Gaussian test - Fix peak at 0.1 mjy/arcsec 2 (y~0.005!) & vary FWHM - Place at Dec=-23 deg & add thermal noise - Observe at 90GHz for 1 hr with ALMA & ACA Input FWHM=30 Peak=1.5mJy/beam 12m 50, 7 mosaics beam=3.6 rms=0.015mjy/beam peak ~3

25 (1) Gaussian test Peak = 0.1 mjy/arcsec 2 1hr integration Covers 2 2 field

26 (2) Simulated Bullet cluster (Akahori & Yoshikawa, in prep.) N-body / SPH simulation N DM = N SPH = 11.6 million particles Two-Temperature structure Non-equilibrium ionization state of heavy elements DM: NFW density profile ICM: beta-model (beta=2/3) Smaller cluster Main cluster initial relative velocity : 3000km/s impact parameter : 0.24 Mpc

27 (2) Simulated Bullet cluster T sl 340 sec = 1.5 Mpc Sx y Rescaled to match the APEX value y=3.3e-4 (Halverson et al. 2009)

28 Input model SZE+sources Thermal SZE at 90GHz with relativistic correction (Itoh et al. 2004) Point sources (Liang et al. 2000; Wilson et al. 2008; Malu et al. 2010) Flux extrapolated form observed freq. & multiplied by 2 strongest : 1mJy Noise Thermal (inst.+atm.) Phase rms = 20deg Gain rms = 1% (for interferometers)

29 Dirty images (raw data, PSF uncorrected) All baselines, 12m+ACA 12m: 45 mosaics ACA: 23 mosaics Long baseline (>18kλ) image FWHM = sources detected above 8σ

30 Deconvolved images (Source subtracted & PSF corrected) Sources: deconvolved by CLEAN Residuals: deconvolved by Maximum Entropy Method 12m only FWHM=4.5 12m+ACA+SD FWHM=4.7 Input model

31 Comparison with the input Mock vs. model 1 arcsec = 4.4 kpc shock Shock is marginally resolved & spatial resolution of SPH simulation is insufficient

32 (3) Simulated sub-cluster merger (Takizawa 2005) Temperature maps of the central slice t=gyr M sun M sun t=0 t=0.44gyr 0.56Gyr 0.67Gyr -Eulerian mesh - N= L=0.8 Mpc Δx=2kpc 0.78Gyr 0.89Gyr 1.0Gyr kt max ~30 kev V max ~4000 km/s Δτ~0.1 Gyr

33 SZE images at 90GHz SPH Bullet (Akahori & Yoshikawa) Δx~20 kpc near the shock (The image is interpolated.) Mesh Bullet (Takizawa 2005) Δx=2 kpc Sides are reversed.

34 Deconvolved image 1 arcsec = 4.4 kpc <n> Tsl Sx 12m: 7 mosaics ACA: single field FWHM=4.5, smoothed to 10 -y

35 How about other bands? Instrument + Sky σ[jy/beam] T sys / t 1/2 for the same arrays

36 How about other bands? KSZ V=3000 km/s Relative time to reach the same S/N in the same effective resolution for the same sky area TSZ kt=15 kev

37 Summary 1. High resolution SZE mapping provides a powerful probe of ICM physics (shock structure, merger dynamics, etc.), complimentary to high-dispersion X-ray spectroscopy and hard X-ray imaging. 2. ALMA+ACA will be able to resolve compact bright clusters with FWHM=5~10 arcsec at < 100GHz. The SZE observations appear challenging at >100GHz, except for very compact targets.