A Measurement of the Kinetic SZ Signal Towards MACS J0717.5

Transcription

1 A Measurement of the Kinetic SZ Signal Towards MACS J0717.5

2 A Measurement of the Kinetic SZ Signal Towards MACS J0717.5, Tony Mroczkowski, Mike Zemcov, Phil Korngut, Jamie Bock, Sunil Golwala, Seth Siegel (Caltech), Esra Bulbul (Harvard), Nicole Czakon, Patrick Koch, Kai-Yang Lin, Keiichi Umetsu (SINICA), Eiichi Egami, Tim Rawle, Marie Rex (Arizona), Adam Mantz (Chicago), Sandor Molnar (Taiwan), Leonidas Moustakas (JPL), Elena Pierpaoli, Jennifer Shitanishi (USC), Erik Reese (Penn), ApJ, 778, 52 (2013)

3 The SZ Effect Thermal SZ effect * T CMB T CMB = f(ν,t e )y * y = n e σ T k B T e m e c 2 dl Kinetic SZ effect - Doppler shift * T CMB T CMB = v z c τ e * τ e = n e σ T dl

4 What is the Kinetic Sunyaev-Zel dovich Effect? ksz brightness is independent of redshift and directly proportional to the line of sight velocity relative to CMB Enables absolute velocity measurements at any redshift Enables direct measurements of both the overall cluster peculiar velocity and of velocity structure within the ICM Measurable ksz signal also sourced by patchy reionization (e.g., Zahn+12) ksz signal is dim order of magnitude below thermal SZ Also significant contamination from: primary CMB fluctuations, background dusty galaxies, radio galaxies, atmospheric brightness fluctuations

5 Galaxy distribution, X-ray, and mass modeling all show four distinct peaks C is the main cluster, A has already passed through along the plane of the sky, B and D are infalling along the line of sight (Ma+2009) MACS J ~382kpc C D B A Limousin et al HSTF814W Chandra Cherry-picked for our ksz study based on 3000 km/s spectroscopic LOS velocity measured for sub-cluster B

6 Bolocam Overview 144-pixel spiderweb bolometer array (NTD- Ge, e.g., Planck-HFI, SPIRE) Two non-simultaneous observing bands, 140 GHz and 268 GHz (well positioned for ksz studies) 10.4 m Caltech Submm Observatory angular resolution 58 and 31 arcsec at 140 and 268 GHz

7 Bolocam Data Reduction Actual Cluster Filtered Cluster I ll skip the specifics, but two things... Removing atmospheric fluctuations also removes a lot of cluster signal Option 1: identically filter a model of the SZ signal prior to fitting Option 2: deconvolve the effects of the filtering This talk focuses on option 1 although we also performed the analysis using option 2 and obtained consistent results background galaxies are very bright at 268 GHz remove using Herschel- SPIRE (600, 850, 1200 GHz)

8 Noise limited by fluctuations in background galaxies cannot go deeper with 10-m telescope brightest object is background galaxy, not SZ cluster Dusty Galaxies at 268 GHz SPIRE detects 200 galaxies! Blue: S/N starting at +4 Cross: dusty galaxy Green: sub-clusters B and C

9 SZ Model Use Chandra pseudo-pressure map to create tsz model This model is not a good fit to Bolocam Data CXO Model Residuals 268 GHz 140 GHz

10 SZ Model F-test additional model component needed for B This is a good fit subcluster B does not have tsz spectrum Data CXO+B Model Residuals 268 GHz 140 GHz

11 Peculiar Velocity Constraints Compute 140/268 GHz brightness within 1 aperture centered on sub-cluster B (also for sub-cluster C) Total SZ brightness is equal to f(ν,t e )y (v z /c)τ e depends on ICM y, τ e, T e, and v z Use X-ray spectroscopic data from XMM/Chandra to constrain T e Assume isothermality so that y T e τ e Then constrain y and v z using our two-band SZ data For sub-cluster B we get v z = ± 900 km/s PDF is not Gaussian our data exclude v z < 0 at a significance of 4.2σ sub-cluster C has v z 500 km/s (consistent with v z = 0)

12 SZ Fits and Peculiar Velocity Constraints Red: tsz Green: ksz Blue: total Good agreement with Ma+2009 spectroscopy Too good? we were VERY conservative with systematic errors I SZ (MJy/ster) I SZ (MJy/ster) Sub cluster B (Model) ν (GHz) Sub cluster C (Model) ν (GHz) v z ( 1000 km/s) v z ( 1000 km/s) Constraints on Sub Cluster B Bolocam SZ (1, 2, 3 sigma) Ma+2009 spectroscopic (+-1 sigma) Y ( ) int Constraints on Sub Cluster C Bolocam SZ (1, 2, 3 sigma) Ma+2009 spectroscopic (+-1 sigma) Y ( ) int

13 3000 km/s is large, compatible with ΛCDM? Cosmological Implications is it Back of the envelope M = M, infall from infinity reaches 3000 km/s 1.5 Mpc ( 2/3 of virial radius) M0717 ksz 68% region N-body simulations, e.g., Lee & Komatsu (2010), at z = 0.5 such velocities do occur for separations R 200 Adapted from Lee & Komatsu (2010)

14 Possible Systematics Chandra and XMM don t agree on temperatures, especially high temperatures like MACS J In our case, the two instruments disagree at the 2σ level Our best-fit v z using the Chandra-only or XMM-only temperature differ by 500 km/s (0.5σ) significance from 0 effectively unchanged due to covariances between T e, y, and v z Does our aperture contain SZ signal from more than one sub-cluster? Are we measuring an intact ICM moving with a single velocity? X-ray temperature towards sub-cluster B is relatively cold, indicating that it is likely still intact Ruan+13 studied exactly this type of scenario using simulated clusters interactions between the merging ICMs tend to behave in a way that leaves the kinetic SZ signal relatively unchanged ( 10%)

15 Summary We have made a resolved measurement of the kinetic SZ signal towards MACS J Our absolute ksz velocities are consistent with the spectroscopic velocities determined by Ma+2009, strengthening the evidence for their proposed merger scenario 1 Sub Cluster B Velocity 1 Sub Cluster C Velocity Likelihood 0.5 Likelihood v ( 1000 km/s) z v ( 1000 km/s) z

16 Expanded ksz Analysis of 10 Clusters New analysis using AzTEC-ASTI 268 GHz data (Grant Wilson, David Hughes, Alfredo Montaña, & David Sanchez) Cluster 140 GHz 268 GHz combined τ e expected σ v RMS (MJy/ster arcmin) km/s per LOS Merging Clusters Abell CL J MACS J MACS J POS Merging Clusters MACS J MACS J MACS J CL J CL J Relaxed Clusters Abell

17 Non-Parametric Joint SZ/X-ray Deprojections Use soft-band X-ray SB plus SZ to constrain thermodynamics of ICM push to larger radii compared to spectroscopic X-ray (Jennifer Shitanishi and Elena Pierpaoli) Density (1/cm^3) 1e-1 1e-2 1e-3 1e Radius (arcsec) R500 Temperature (kev) Radius (arcsec) R500 Pressure (1e-11 erg/cm^3) 1e1 1e0 1e Radius (arcsec) R500 MACS J Cool-Core Cluster at z = 0.44 Black = Non-Parametric Deprojection Blue = Parametric Fit Green = X-ray Only (Cavagnolo+06) Red = SZ Only (Sayers+13)

18 Non-Parametric Joint SZ/X-ray Deprojections Individual cluster profiles have modest S/N, but we have 45 clusters scale by characteristic radius/normalization to determine ensemble average & cluster-to-cluster scatter Density (1/cm^3) 1e-2 1e-3 1e-4 1e Radius (arcsec) R500 Temperature (kev) Radius (arcsec) R500 Pressure (1e-11 erg/cm^3) 1e1 1e0 1e-1 1e Radius (arcsec) R500 MACS J Non-Cool-Core Cluster at z = 0.54 Black = Non-Parametric Deprojection Blue = Parametric Fit Green = X-ray Only (Cavagnolo+06) Red = SZ Only (Sayers+13) Purple = Isothermal beta (LaRoque+06)

19 Bolocam Public Data Release Bolocam 140 GHz SZ data for 47 clusters are now publicly available via the NASA IRSA website ( Includes arcmin images with 1 arcmin resolution, along with gnfw model fits Nicely complements the Planck data Typical S/N of 12 Contains many of the popular clusters All 25 CLASH clusters All 6 Frontier Fields All 12 MACS high z

20 Bolocam Public Data Release