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P h o t o z z=0.8 z=0.6 z=0.4 z=0.2 I AB <25 1.4Mio galaxies X-ray contours. X-ray galaxy groups in zCOSMOS. Alexis Finoguenov MPE/UMBC +zCOSMOS team. X-ray+red sequence: 278 Xray+spectroscopy: 195 z<0.8 152/175 91% 0.8<z<1 37/50 74% z>1 6/53 11%. N(z)=>2.
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Photoz z=0.8 z=0.6 z=0.4 z=0.2 IAB<25 1.4Mio galaxies X-ray contours
X-ray galaxy groups in zCOSMOS Alexis Finoguenov MPE/UMBC +zCOSMOS team
X-ray+red sequence: 278 Xray+spectroscopy: 195 z<0.8 152/175 91% 0.8<z<1 37/50 74% z>1 6/53 11% N(z)=>2 View on baryons from COSMOS
X-ray only groups View on baryons from COSMOS
How X-ray groups are different from spectroscopic groups? Spec. completeness is better at low z But drops faster with redshift
Comparison of a group definition X-ray only Spec-z groups with X-rays Spec-z 3 member groups, no X-rays: stacked X-ray signal @<2.e-16> @z>0.8 X-rays (`a 6.e-16 cgs) are more sensitive group tracer compared to IAB<22.5 galaxies Inside dense LSS Fraction of X-ray groups increases by a factor of 2 View on baryons from COSMOS
Stacked X-ray detection of Knobel groups View on baryons from COSMOS
Stacked detection of spectro-z groups
Lx-sigma relation View on baryons from COSMOS
LSS at 0.12, 0.22, 0.34, 0.37, 0.51, 0.73, 0.89 (Optical groups:0.22,0.36,0.38) K.Kovac
Resolving LSS with X-ray groups View on baryons from COSMOS
Fraction of matter resolved in groups Simulations… A. Faltenbacher, AF, N. Drory 2010 ApJ
Environmental dependence of galaxy mass function View on baryons from COSMOS
No change in HOD! View on baryons from COSMOS
Bump in galaxy mass function:centrals vs sattelites View on baryons from COSMOS
Conclusions • X-ray groups approach the status of being spectroscopically confirmed. • X-ray groups are not a subsample of spectroscopic groups • Groups are tracers of density field and can be used to overcome to sample variance. View on baryons from COSMOS
People involved • Masayuki Tanaka – properties of galaxies in X-ray groups using zCOSMOS • Stefania Giodini– HOD of galaxies, galaxy mass function, fossil groups • Alexie Leauthaud– properties of BCGs • Berian James – conditional mass function – modeling • Andreas Faltenbacher – conditional mass function – simulations • Katarina Kovac – density fields • Angela Iovino, MicholBolzonella, Olga Cucciatti – properties of galaxies • Viola Allevato(my PhD student) – clustering analysis • Michael Ballogh – 10 groups at z~0.9 with Gemini • Masayuki Tanaka – groups at z>1 with Subaru • Mara Salvato – high-z clusters • Simona Mei et al. FORS2 program – already 350 redshifts for groups added (or 30% of total number) • And likely you! (a number of on-going efforts!) View on baryons from COSMOS