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my dream cluster survey

my dream cluster survey. Yen-Ting Lin Institute for the Physics and Mathematics of the Universe The University of Tokyo. outline. fundamental issues in cluster formation and evolution an ideal cluster survey an IRAC view of cluster galaxy evolution from z=0.4 to z=1.4. fundamental issues.

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my dream cluster survey

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  1. my dream cluster survey Yen-Ting Lin Institute for the Physics and Mathematics of the Universe The University of Tokyo

  2. outline • fundamental issues in cluster formation and evolution • an ideal cluster survey • an IRAC view of cluster galaxy evolution from z=0.4 to z=1.4

  3. fundamental issues • how did cluster galaxy populations form and evolve? • luminosity function • morphological mix • star formation history • brightest cluster galaxies (BCGs) • interactions between galaxies and intracluster medium (ICM) throughout cluster lifetime? • measurement of cluster mass (critical for doing sciences with clusters) • how to meaningfully compare clusters at different redshifts?

  4. luminosity function • LF as a function of cluster mass and cluster-centric distance • redshift evolution • build up of the faint galaxies on the red sequence • origin? • LF of blue galaxies: spectroscopy or/and photometric maximum likelihood approach

  5. luminosity function

  6. blue galaxy luminosity function?

  7. morphological mix • fraction of different morphological types as a function of cluster properties • redshift evolution • local processes more important than cluster membership? • mass-selection vs luminosity-selection of morphology-density relation • rise of S0

  8. morphological mix

  9. star formation history • star formation–density relation evolves with time • at z~1 SF comments at highest densities • opposite trend at z~0 • continuous formation of non-SF/early-type galaxies since high-z, where high-density region leads the process • leads to an age–density relation at fixed morphology • Thomas et al (2005) found strong dependence of early-type ages with environment • Wolf et al (2007) found an age–density relation for A901/902 • Trager et al (2008) didn’t see it for Coma • Poggianti et al (2008) didn’t see it in EDisCS • how is SF shut down? where? • progenitors of bright and faint S0?

  10. star formation–density relation

  11. BCG formation • are BCGs special? • they are larger, have higher velocity dispersion, larger fraction of dark matter, higher α/Fe ratio, higher probability to host radio-loud AGNs, than non-BCGs of same stellar mass, and have different fundamental plane projections (von der Linden et al 07) • magnitude gap between BCG and 2nd brightest galaxy larger than expected than just being the statistical extreme • mass assembly history • late time mergers certainly occurred • are they enough?

  12. : observed Lbcg–Ltot x: mean “statistical” Lbcg–Ltot : one simulated Lbcg–Ltot Lin, Ostriker & Miller (09) • results based on 494 low-z clusters from the C4 catalog (Miller et al ‘05) • dobs = log[Lbcg,obs]-log[Lbcg,sim]; dsim = log[Lbcg,sim]-log[Lbcg,sim] • overall the observed Lbcg–Ltot relation has 0.8% chance to be statistical (0.03% for BCGs in high luminosity clusters; 55% for BCGs in low luminosity systems) • BCGs in massive clusters must experience mergers

  13. outstanding issues • study the evolution of LF, morphology mix, SF, and BCG with clusters that form an evolutionary track • more sensible way to compare clusters at different redshifts • need cluster mass • LF • blue galaxy LF • build up of faint end of red sequence • what transforms morphology? • what shuts down SF? • better measurement of SFH • better way to compare observed luminosity/stellar mass growth of BCGs with theoretical models

  14. an ideal cluster survey • must address fundamental issues in cluster formation and evolution, in addition to those just mentioned • spatial distribution of various galaxy populations • AGN content as a function of cluster mass and redshift • effect of cluster merger and substructures in galaxy evolution • merger rate as a function of halo mass and galaxy mass • facilitate comparison of cluster galaxy properties with the field • baryon fraction as a function of cluster mass and redshift • interactions between galaxies/intracluster space stars and ICM • etc • large area, multiwavelength survey, with large cluster sample spanning wide range in mass and redshift space • different detection algorithms (photometric, weak lensing, spectroscopic, X-ray, Sunyaev-Zeldovich effect), different mass measurements

  15. an ideal cluster survey • makes sense to study galaxy evolution using X-ray or SZE selected clusters, but mass limits may restrict comparisons using evolutionary tracks • perhaps more realistic to conduct large scale imaging and spectroscopic survey (ie a deep version of SDSS), selecting clusters that follow evolutionary tracks for further follow up (spectroscopy, UV/near-IR/IR imaging, X-ray, SZE, radio) • SUMIRE+ACT+eROSITA sounds like great combination!

  16. cluster galaxy evolutionfrom z=1.4 to z=0.4 collaborators: Mark Brodwin, Anthony Gonzalez, Adam Stanford

  17. cluster evolution with Spitzer • studying galaxy evolution within clusters that follow an evolution sequence • connecting halos via mass growth history • IRAC shallow survey (PI: Eisenhardt) • 9 deg2 Bootes field, with optical data from NDWFS and near-IR data from NEWFIRM • good photometric redshift • detecting clusters with wavelet from density peaks • ~335 4.5m selected groups/clusters out to z~2 • galaxy number and luminosity (Ltot) in each cluster determined via statistical background subtraction • lack of cluster mass info (although with good stellar mass measurements)

  18. De Lucia & Blaizot (07) cumulative halo mass function cumulative cluster luminosity function number density number density X X mass luminosity BCGs evolution seen by IRAC • connecting halos via mass growth history • luminosity measured within 5 arcsec aperture (not optimal…) • normalized to the passively evolving L* from single burst model • not much evolution seen: from 3.5L* at z~1.3 to 5.5L* at z~0.5 • much slower than the halo mass growth; also slower than (one) model prediction • need to find a meaningful way to compare to theoretical predictions preliminary! Lin et al (in prep.) Lin et al (in prep.)

  19. cluster galaxy population evolution • calculate mean number of member galaxies • look at the change of member galaxy number from z~1.3 to z~0.5 • growth in number roughly scales with mass growth • BCG growth is slower preliminary! Lin et al (in prep.)

  20. conclusion • some of the fundamental issues in cluster formation and evolution • existing cluster samples too small to facilitate faithful comparison of progenitor-descendent clusters • deep, wide-field survey absolutely needed to construct large cluster sample that spans full range in mass and redshift space • weak lensing seems to be most efficient way to obtain cluster mass for surveys with Subaru • spectroscopy absolutely essential to reveal morphological transform and SFH • SUMIRE in combination with ACT/eROSITA enables studying cluster galaxy evolution using (optically) unbiased cluster sample

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