On the Trail of the Most Massive Clusters in the Universe!

Transcription

1 On the Trail of the Most Massive Clusters in the Universe Jack Hughes Rutgers University In collaboration with Felipe Menanteau (Illinois), L. Felipe Barrientos, and Leopoldo Infante (PUC)

2 Talk Plan Brief review and update on ACT-CL J El Gordo Taking steps to find other examples of massive high-z clusters The next step: the Advanced ACTPol project.

3 The Exceptional Cluster ACT J CMB Optical X-ray Detected in 2008 ACT maps of Southern Strip o Strongest SZ decrement over 755 deg 2 (South + Equator) Optical follow-up o Imaged (griz) at SOAR/SOI (9-12 Dec 2009) o VLT/FORS2 MOS (10-hrs) + Imaging (2 hrs) in Jan redshifts Chandra X-ray Observations o ACIS-I, 60 ks, observed 27 Jan 2011 o Another 300 ks in Feb 2012 Spitzer IRAC warm-phase follow-up o Imaged at 3.6 µm and 4.5 µm Hubble Space Telescope o Optical imaging

4 How We Weighed El Gordo (2012 version) VLT FORS2 (Jan 2011, 10hrs), redshifts for 89 members: Chandra/ACIS (Jan 2011, 60 ks exposure): Combined (χ 2 combined) optical+x-ray+sz: Evrard et al. (2008) Kravtsov, Vikhlinin & Nagai (2006) Vikhlinin et al. (2009) ACT/SZ decrement, ytcmb - Mass CL J (z=0.89) M 200 =(1.38 ± 0.20) h 1 70 M SPT-CL Sehgal J et al. (z=1.14) (2011) M 200 =(1.27 ± 0.21) h 1 70 M

5 Rarity of El Gordo " (Based on its exceptional mass) Combined Mass from optical +X-ray+SZ: Menanteau et al. (2012, ApJ, 748,7) Area of survey: ACT: 755 deg 2 ACT+SPT: 2800 deg 2 Mortonson et al. (2011) exclusion curves for ΛCDM and quintessence parameter distribution. ( El Gordo ) Cluster is unlikely in the ACT survey area alone (3σ), but still allowed in the ACT+SPT sky region if its mass is 1-σ or more below the nominal mass. But need accurate mass not based on gas properties.

6 How We Weighed El Gordo (2014 version) Weak Lensing - Hubble Space Telescope Advanced Camera for Surveys - 2x1 mosaic (to cover NW and SE components) in filters F625W, F775W, F850LP (~2500 s per exposure) - 2x2 mosaic in F606W, 1 ptg in F814W (~1900 s per exposure) M 200 =(3.13 ± 0.56) h 1 70 M Jee, JPH, et al. (2014)

7 Rarity of El Gordo " (Based on its exceptional mass) New Weak Lensing mass: M 200 =(3.13 ± 0.56) h 1 70 M Area of survey: ACT: 755 deg 2 ACT+SPT: 2800 deg 2 Mortonson et al. (2011) exclusion curves for ΛCDM and quintenssence parameter distribution. Caveats: Mass extrapolated to R 200 ; 20%-30% mass uncertainty Jee, JPH et al. (2014, ApJ, 785,20) " " Eddington-bias corrected ( El Gordo ) due to triaxiality; Harrison & Hotchkiss (2013) consider broader rare cluster statistical measures (increases limits by x2) El Gordo is rare, but not in tension with ΛCDM

8 Updates on El Gordo Stay tuned for a report on El Gordo s dynamical state - Karen Ng s talk on Friday afternoon Next a brief report on X-ray results - cold front - merger shock Ng et al. 2015, arxiv:

9 SE Profile: Cold front Edge of core is quite sharp (unresolved by Chandra) Interior: nearly constant density Exterior: β-law profile Density jump at interface

10 A Giant Double Radio Relic Confirmed by ATCA data at 2.1 GHz (highest redshift relics) Relic widths unresolved (< 23 kpc); also highly polarized Radio halo discovered too (610MHz GMRT)" " " Lindner, Baker, JPH, et al. (2013)

11 NW Radio Relic: X-ray Surface Brightness Profile ATCA 2.1 GHz Chandra (0.5-2 kev) X-ray data shows break in both surface brightness and projected temperature profile at edge of radio relic

12 Talk Plan Brief review and update on ACT-CL J El Gordo Taking steps to find other examples of massive high-z clusters The next step: the Advanced ACTPol project.

13 (Planck Collaboration XXIX et al. 2013) Sunyaev-Zel dovich Cluster Catalogs circa March 2013 ACT-CL J (RCS2327) El Gordo Planck All sky Multiple frequencies Large beam (5-10 ) M>5x10 14 M # ACT/SPT deg 2 total - Narrow beam (~1 ) - M>2-3x10 14 M # Note high-z ACT extreme clusters - El Gordo /RCS Planck detections at S/N of 8.0 and 6.3

14 Planck SZ (PSZ1) Sample 861 confirmed (with redshifts) Confirmation process favored candidates with some type of external detection in optical and X-ray surveys - Favored lower redshift systems (z<0.6) - 6% of confirmed clusters are at z>0.6 vs 23% expected for M>5x10 14 M # (Jenkins+2001, Tinker+2008) 366 candidates (as of March 2013) at S/N> confirmed subsequently but prior to PSZ2 (Planck collaboration+2014; Bleem+2014); <z> =0.45, max z=0.92 Expected purity >84% El Gordo & RCS2327 detected by ACT in only 7% of the sky there should be several more in PSZ

15 PSZ1 Unconfirmed Sample Class 1 Class 2 Class 3

16 Archival X-ray Confirmation Search within pointed observations Einstein Observatory IPC, ROSAT PSPC, Chandra, XMM-Newton, Swift XRT Modest yield: 16 high likelihood candidates (including 1 from the EO IPC and 8 from the Swift XRT) ROSAT All Sky Survey Approx. 100 candidates with some X-ray flux August Miller s REU (summer 2014)

17 Optical/NIR Confirmation Brightest cluster galaxy (BCG) Visible to z>1(at r limit ~23.5) Red sequence Visible to z 0.8 (at r limit ~23.5) NIR (K S ) imaging L* galaxies to z~1.5 (at K s limit ~22) BCGs in ACT southern sample SOAR Optical Imager [SOI] and SPARTAN Mayall MOSAIC and NEWFIRM 2013B, 2014A, and 2014B semesters 24 nights awarded; acquired useful data on19 nights Joint NOAO/Chilean Observing Program Observed 72 candidates in griz and 34 in Ks

18 Status vs. Planck S/N (PSZ1)

19 Status vs. Planck S/N (PSZ2) Additional confirmations of PSZ1 candidates in PSZ2-26 (15) were observed by us in optical (IR) PSZ1 clusters dropped from PSZ2 for reason of - low S/N (10) - new pt source msk (7) - IR contamination (10) - internal consistency (2)

20 Status vs. Planck S/N (PSZ2)

21 Talk Plan Brief review and update on ACT-CL J El Gordo Taking steps to find other examples of massive high-z clusters The next step: the Advanced ACTPol project.

22 ACT

23 ACTPol: Sky Coverage Season 1 (2013) deep scans in four patches (70 deg 2, ), mostly observed at night in sky regions with rich overlap of λλλ datasets. Only 1 array at 150 GHz.

24 ACTPol: Stacked CMB Halo Lensing Unlensed CMB Lensed CMB Difference Madhavacheril et al. 2014, arxiv: SDSS/BOSS 12,000 CMASS galaxies 0.4<z<0.7 reside in ~10 13 M # halos Detect lensing at 3.2σ M 200 =2.0± M # c 200 = 5.4±0.8

25 starting

26 Advanced ACTPol (AdvACTPol)

27 Summary El Gordo remains the top of the heap in terms of massive, high redshift clusters. Our recent Hubble weak lensing analysis confirms its high mass. The cluster contains a cold front and a high speed shock both with X-ray measured properties We are extending our search for extreme clusters to the all-sky Planck survey. Already we have found a couple of dozen new clusters to characterize. Much more work now with PSZ2 The approved Advanced ACTPol project, starting 2016, will provide huge samples of SZ-selected clusters and mm-band selected galaxies for further investigation of the distant Universe.

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