Imaging the Kinetic SZ Signal in a Sample of 10 Massive Clusters

Transcription

1 Imaging the Kinetic SZ Signal in a Sample of 10 Massive Clusters (CIT), Sunil Golwala (CIT), Alfredo Montaña (INAOE), Daisuke Nagai (Yale), Tony Mroczkowski (ESO), Erik Reese (Moorepark), David Sanchez (INAOE), Grant Wilson (UMASS), Mike Zemcov (RIT), John Zuhone (CfA)

2 In 2013 we measured v z of a merging sub-cluster in MACS J using 140/268 GHz Bolocam SZ observations Optical spectroscopy (Ma+2009): ± 250 km/s Our ksz measurement (Sayers+2013): ± 900 km/s NIKA ksz measurement (Adam+2017): ± 500 km/s Wehaveextendedouranalysis using similar datafor a sample of 10 clusters (6 with AzTEC/ASTE at 268 GHz)

3 The SZ Effect Thermal SZ effect * T CMB T CMB T e τ e Kinetic SZ effect - Doppler shift * T CMB T CMB v z τ e Can determine τ e, T e, and v z via SZ brightness in 3+ bands For our two-band analysis we use Chandra spectroscopy to determine T e (completed the Chandra analysis for 3 clusters)

4 Bolocam and AzTEC/ASTE Overview 144-pixel bolometric imaging cameras Two non-simultaneous observing bands, 140 GHz and 268 GHz (well positioned for ksz studies) 10 meter class telescopes angular resolution of 60 and 30 at 140 and 268 GHz For this analysis we degrade both bands to a common resolution of 70

5 SZ Data Reduction Actual Cluster Filtered Cluster Without getting into too much detail... Removing atmospheric fluctuations also removes a lot of cluster signal Option 1: filter a candidate cluster model in an identical way this is how we obtain bulk cluster v z Option 2: deconvolve the filter to obtain an unbiasedimage this ishow weobtainkszv z images, with Planck data to help constrain the overall mean signal in the deconvolved images background galaxies are very bright at 268 GHz remove using Herschel- SPIRE (600, 850, 1200 GHz)

6 Noise limited by variations in background galaxy signal Dusty Galaxies at 268 GHz brightest object usually a background galaxy, not SZ cluster Detect 10s of galaxies at 268 GHz plus 100 more with SPIRE Each cross is a detected galaxy Extrapolate SPIRE detections to 268 GHz via greybody fit Sν = S 0 (1 e (ν/ν 0) β )B(ν,T dust ) Float T dust, set β = 2.15 based on empirical calibration

7 SZ Spectral Fits To Bulk Signal CL J RX J Fit elliptical gnfw model to each band bulk SZ signal Obtain best-fit relativistically-corrected tsz and ksz

8 Constraints on τ e and v z MACS J MACS J SZ spectral fits, including relativistic corrections, then yield τ e and v z when combined with Chandra T e constraint

9 Constraints on τ e and v z A697 A1835 CL J CL J MACS J MACS J MACS J MACS J2129.4

10 Best-Fit Bulk Cluster v z While the ksz depth is fairly uniform over the sample, variations in τ e produce nonuniform v z uncertainties From Mann+Ebeling (2012), plus a handful of other studies, classify as LOS merger, POS merger, or relaxed Non-zero ensemble average due to LOS mergers (+960 ± 360 km/s) Cluster v z (km/s) LOS Merging Clusters A ± 1340 MACS J ± 920 MACS J ± 480 MACS J ± 730 POS Merging Clusters MACS J ± 690 MACS J ± 1160 MACS J ± 1350 CL J ± 970 CL J ± 770 Relaxed Clusters A ± 1210 Ensemble Average AVG ± 260 Lindner+ (2015) ± 380 indicates Chandra analysis is not yet complete and so T e was assumed to be 10 kev. Lindner+ (2015) based on ACT/LABOCA analysis of 11 clusters

11 Two-Band SZ Images A1835 after subtracting background galaxies, deconvolving filtering, and smoothing to an effective resolution of 70

12 Resolved Images of τ e and v z Solve for the value of τ e and v z at each map pixel (smoothed to a resolution of 70 ) see MACS J above Contours start at 2σ and separated by 1σ For presentation, appodize edges of v z map where τ e is small

13 MACS J MACS J2129.4

14 v z Image of A697 A697 shows one of thestrongest ksz signals in our sample (it is one of the likely LOS mergers identified in other analyses) Qualitatively, the ksz v z image matches a linear fit with position to the galaxy spectroscopy of Girardi+ (2006)

15 Interpretation of v z Images To search for resolved velocity structure, determine peak-to-peak of the ksz signal (in SNR) Compare to expected distribution for case of noise only (no LOS v z sub-structure) Previously identified LOS mergers have larger signals than previously identified POS mergers and relaxed Red = LOS mergers, Green = POS mergers, Blue = Relaxed A697andMACSJ2129.4appeartobebinaryLOSmergers compare to binary merger simulations to constrain geometry

16 Summary We have obtained resolved ksz images of a sample of 10 clusters The SZ analysis is basically complete at this point, will soon finalize the Chandra X-ray analysis Results are in good agreement with previous analyses (mainly Mann+Ebeling) LOS mergers have larger ksz signals than POS mergers and relaxed clusters Based on our SZ analysis and previous results, A697 and MACS J appear to be LOS binary mergers will peform detailed comparison with simulations to constrain geometry

17 Use high quality multiwavelength data to constain increasingly complicated parametric models of gas and total mass CLASH HST WL/SL, Subaru WL, Chandra X-ray, Bolocam SZ First effort fit spherically symmetric models to a set of 6 CLASH clusters that have extremely round POS morphology (arxiv: , ApJ in process)

18 Spherical Multi-wavelength CLASH Analysis Value of 1.0 corresponds to Nelson+2014 prediction For 5/6 clusters, c/m values are consistent and constraints are improved significantly with additional data Inconsistent for A383, likely due to LOS elongation No evidence for non-thermal pressure upper limit inconsistent with Nelson+14 (selection? LOS compresson?)

19 Extending analysis to allow for ellipsoidal triaxial geometry Two methods one led by Mauro Sereno (CLUMP-3D) and one based on JACO using Siegel+16 technique

20 p Triaxial Multi-wavelength CLASH Analysis CLUMP3D (observed) ΛCDM relaxed MUSIC2 CLASH-like prior q mat,1 (minor/major axis ratio) p CLUMP3D (observed) MUSIC2 CLASH-like prior cos Ф (LOS inclination of major axis) Sereno+ CLUMP-3D analysis of 16 CLASH clusters nearly complete look for arxiv postings in the coming weeks Initially focus on total mass parameters find good statistical agreement with simulations (CLASH-like MUSIC2 (Meneghetti+2014) and relaxed Bonamigo+2015) Interpretation of gas parameters will be soon to follow...