IN GALAXY GROUPS? WHERE IS THE CENTER OF MASS MATT GEORGE. 100 kpc 100 kpc UC BERKELEY

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1 WHERE IS THE CENTER OF MASS IN GALAXY GROUPS? 100 kpc 100 kpc MATT GEORGE UC BERKELEY WITH ALEXIE LEAUTHAUD, KEVIN BUNDY, JEREMY TINKER, PETER CAPAK, ALEXIS FINOGUENOV, OLIVIER ILBERT, SIMONA MEI AND THE COSMOS COLLABORATION

2 Motivation for Finding Centers BCG properties and galaxy evolution Cluster finding Mass determination - satellite kinematics - gravitational lensing Halo occupation models Miscentering Fraction Fraction of halos where BCG Center Sloshing and ICM heating Measuring mass-concentration and intrinsic alignments log(mhalo) Skibba et al. 2010

3 Weak Lensing Signal ΔΣ (h M pc -2 ) MaxBCG Increasing richness Projected Distance from Center (h -1 Mpc) Model components: NFW Offset NFW BCG Neighboring halos Non-weak shear Total Johnston et al. 2010

4 Weak Lensing Signal ΔΣ (h M pc -2 ) MaxBCG Increasing richness Projected Distance from Center (h -1 Mpc) Model components: NFW Offset NFW BCG Neighboring halos Non-weak shear Total Fraction of Groups with Correct Center Distribution of Offsets from True Center Fraction Richness (N200) Offset (Mpc) Johnston et al. 2010

5 COSMOS: A panchromatic survey XMM kev CHANDRA GALEX FUV, NUV Magellan - IMAX HST-ACS I814W VLT-VIRMOS CFHT Megacam u*, i* Spitzer MIPS 160, 70, 24 µm Spitzer IRAC 8, 6, 5, 4, 3 µm CFHT Wircam K VLA 20 cm IRAM -30m 1.2 mm Subaru SCam B,V,r,i,z, NB816 NOAO Ks CSO Bolocam 1.1 mm

6 COSMOS: A panchromatic survey X-ray group selection XMM kev CHANDRA GALEX FUV, NUV Magellan - IMAX HST-ACS I814W VLT-VIRMOS CFHT Megacam u*, i* Spitzer MIPS 160, 70, 24 µm Spitzer IRAC 8, 6, 5, 4, 3 µm CFHT Wircam K VLA 20 cm IRAM -30m 1.2 mm Subaru SCam B,V,r,i,z, NB816 NOAO Ks CSO Bolocam 1.1 mm

7 COSMOS: A panchromatic survey X-ray group selection XMM kev CHANDRA GALEX FUV, NUV Magellan - IMAX HST-ACS I814W VLT-VIRMOS CFHT Megacam u*, i* ACS imaging for lensing Spitzer MIPS 160, 70, 24 µm Spitzer IRAC 8, 6, 5, 4, 3 µm CFHT Wircam K VLA 20 cm IRAM -30m 1.2 mm Subaru SCam B,V,r,i,z, NB816 NOAO Ks CSO Bolocam 1.1 mm

8 XMM kev CHANDRA COSMOS: A panchromatic survey UV/Opt/IR SEDs for photometric redshifts and stellar masses ACS imaging for lensing X-ray group selection GALEX FUV, NUV Magellan - IMAX HST-ACS I814W VLT-VIRMOS CFHT Megacam u*, i* Spitzer MIPS 160, 70, 24 µm Spitzer IRAC 8, 6, 5, 4, 3 µm CFHT Wircam K VLA 20 cm IRAM -30m 1.2 mm Subaru SCam B,V,r,i,z, NB816 NOAO Ks CSO Bolocam 1.1 mm

9 X-ray Selected Groups Mass (M ) Finoguenov et al (+2010 in prep) X-ray Luminosity (10 42 erg/s) Leauthaud et al X-ray position gives RA, Dec (uncertain by up to 32 ) Red sequence overdensity gives z, refined w/ spectroscopic z MWL-LX relation gives radius assuming a mass-conc. relation Remove groups with possible projections or overlap

10 Member Selection with Photometric Redshifts dn/dz (group), dn/dz (field), P(zphot) z dn/dz (group), dn/dz (field), P(zphot) z Identify members using photoz probability distribution + measured field/group densities

11 Photometric Redshifts Photometry in 31 UV/Opt/IR bands σ(zspec-zphot) 0.01 for mi < 24 ~94000 galaxies with 0<z<1, mf814w < 24.2 ~3500 total members in 120 groups PDF gives good estimate of redshift uncertainty Ilbert et al. 2009

12 Photometric Redshifts Photometry in 31 UV/Opt/IR bands σ(zspec-zphot) 0.01 for mi < 24 ~94000 galaxies with 0<z<1, mf814w < 24.2 ~3500 total members in 120 groups PDF gives good estimate of redshift uncertainty Ilbert et al dn/dm/ ! z med σz PDF dn/dc/ ! z med σz PDF F814W magnitude M(NUV)-M(R) color dn/dz/ z z dn/dm/ F814W magnitude F814W magnitude 0.01

13 Characterizing the Member Selection Test purity and completeness using spectroscopic redshifts ~20% of photoz-selected members have spectra Spectroscopic member zgal-zgroup < 0.005(1+zgroup) Purity = fraction of selected objects that are members Completeness = fraction of members that are selected

14 Characterizing the Member Selection Test purity and completeness using spectroscopic redshifts ~20% of photoz-selected members have spectra Spectroscopic member zgal-zgroup < 0.005(1+zgroup) Purity = fraction of selected objects that are members Completeness = fraction of members that are selected Caveats: membership criterion is ~3-5σv for groups varying uncertainties for zgal and zgroup mocks will improve our characterization of selection (Peter Behroozi, Michael Busha, Risa Wechsler)

15 1.0 Purity and Completeness Fraction Fraction z spec Bright Faint F814W Fraction Fraction Blue Green Red M(NUV)-M(R) Distance to X-ray center (R/R 200 )

16 1.0 Purity and Completeness Fraction Fraction Bright Faint F814W z spec Field Contamination Fraction Fraction Blue Green Red M(NUV)-M(R) Distance to X-ray center (R/R 200 )

17 1.0 Purity and Completeness Fraction Fraction Bright Faint F814W z spec Poisson Uncertainties (~700 members with spectra) Fraction Fraction Blue Green Red M(NUV)-M(R) Distance to X-ray center (R/R 200 )

18 Bullet Cluster Finding Group Centers A2390 Oguri et al. 2010

19 Stacked Weak Lensing Cluster 1 Cluster 2 Cluster 3 1. Find members

20 Stacked Weak Lensing Cluster 1 Cluster 2 Cluster 3 1. Find members 2. Determine centers

21 Stacked Weak Lensing Cluster 1 Cluster 2 Cluster 3 1. Find members 2. Determine centers 3. Measure shapes of background sources

22 Stacked Weak Lensing Cluster 1 Cluster 2 Cluster 3 1. Find members 2. Determine centers 3. Measure shapes of background sources

23 Stacked Weak Lensing 1. Find members 2. Determine centers 3. Measure shapes of background sources 4. Stack on centers

24 Stacked Weak Lensing Good center Bad center 1. Find members 2. Determine centers 3. Measure shapes of background sources 4. Stack on centers 5. Measure tangential shear in radial bins

25 Preliminary Results 400 BCG galaxy with largest stellar mass within NFW scale radius of X-ray center Weak Lensing Signal!" = = "(<R) - "(R) (h 72 M O pc -2 ) N Lens : 88 Redshift: Physical transverse distance, R (h 72 Mpc)

26 BCG X-ray 400!" = = "(<R) - "(R) (h 72 M O pc -2 ) N Lens : 88 Redshift: 0.60 N Lens : 88 Redshift: Physical transverse distance, R (h 72 Mpc) Physical transverse distance, R (h 72 Mpc)

27 BCG X-ray 400!" = = "(<R) - "(R) (h 72 M O pc -2 ) N Lens : 88 Redshift: 0.60 log 10 (M 200 ): Concentration: 4.19 # 2 : 5.22 d.o.f.: 7 N Lens : 88 Redshift: Physical transverse distance, R (h 72 Mpc) Physical transverse distance, R (h 72 Mpc) NFW Central Galaxy Offset NFW Total

28 BCG X-ray 400!" = = "(<R) - "(R) (h 72 M O pc -2 ) N Lens : 88 Redshift: 0.60 log 10 (M 200 ): Concentration: 4.19 # 2 : 5.22 d.o.f.: 7 N Lens : 88 Redshift: 0.60 log 10 (M 200 ): Concentration: 4.19 # 2 : d.o.f.: Physical transverse distance, R (h 72 Mpc) Physical transverse distance, R (h 72 Mpc) 60 NFW 50 Distribution of offsets Central Galaxy Offset NFW Total N groups Radial Offset (kpc)

29 BCG Luminosity-Weighted Centroid 400!" = = "(<R) - "(R) (h 72 M O pc -2 ) N Lens : 103 Redshift: 0.59 log 10 (M 200 ): Concentration: 3.99 # 2 : 7.83 d.o.f.: 7 N Lens : 103 Redshift: 0.59 log 10 (M 200 ): Concentration: 3.99 # 2 : d.o.f.: Physical transverse distance, R (h 72 Mpc) Physical transverse distance, R (h 72 Mpc) 60 NFW 50 Distribution of offsets Central Galaxy Offset NFW Total N groups Radial Offset (kpc)

30 BCG SM-Weighted Centroid 400!" = = "(<R) - "(R) (h 72 M O pc -2 ) N Lens : 97 Redshift: 0.58 log 10 (M 200 ): Concentration: 4.01 # 2 : 6.34 d.o.f.: 7 N Lens : 97 Redshift: 0.58 log 10 (M 200 ): Concentration: 4.01 # 2 : d.o.f.: Physical transverse distance, R (h 72 Mpc) Physical transverse distance, R (h 72 Mpc) 60 NFW 50 Distribution of offsets Central Galaxy Offset NFW Total N groups Radial Offset (kpc)

31 BCG 2nd Most Massive Member 400!" = = "(<R) - "(R) (h 72 M O pc -2 ) N Lens : 101 Redshift: 0.57 log 10 (M 200 ): Concentration: 3.91 # 2 : 1.84 d.o.f.: 7 N Lens : 101 Redshift: 0.57 log 10 (M 200 ): Concentration: 3.91 # 2 : d.o.f.: Physical transverse distance, R (h 72 Mpc) Physical transverse distance, R (h 72 Mpc) 60 NFW 50 Distribution of offsets Central Galaxy Offset NFW Total N groups Radial Offset (kpc)

32 Summary Galaxy with highest stellar mass near X-ray center appears to be the best tracer of CM for this catalog Other tracers can be offset by ~few hundred kpc Offsets can be due to: interlopers and incompleteness scatter in observables intrinsic separation? To do: study offset-dependent properties satellite and halo concentration