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The build-up of the Red Sequence

The build-up of the Red Sequence. Lisa Young (NMT) On behalf of the Atlas3D team. The Team. PIs: Michele Cappellari (Oxford), Eric Emsellem (Lyon), Davor Krajnović (Oxford), Richard McDermid (Gemini) CoIs / Students: Roland Bacon, Maxime Bois, Frederic Bournaud,

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The build-up of the Red Sequence

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  1. The build-up of the Red Sequence Lisa Young (NMT) On behalf of the Atlas3D team

  2. The Team PIs:Michele Cappellari (Oxford), Eric Emsellem(Lyon), Davor Krajnović (Oxford), Richard McDermid (Gemini) CoIs / Students: Roland Bacon, Maxime Bois, Frederic Bournaud, Martin Bureau, Roger Davies, Tim de Zeeuw, Jesus Falcon-Barroso, Sadegh Khochfar, Harald Kuntschner, Raffaella Morganti, Thorsten Naab, Tom Oosterloo, Marc Sarzi, Nicholas Scott, Paolo Serra, Remco van den Bosch, Glenn van de Ven, Gijs Verdoes-Kleijn, Lisa Young, Anne-Marie Weijmans

  3. Red sequence≡ mixture of remnants from mergers of gas-rich galaxies (blue cloud) gas-poor galaxies (red sequence)[e.g. Robertson et al. 2006; Cox et al. 2006; Cattaneo et al. 2006] Hierarchical Galaxy Formation Z=0 Z=18 Millenium (Springel et al, 2005) RED U - B BLUE MASS

  4. Goal: To use the structures of nearby early-type galaxies (internal kinematic substructures, stellar populations, and gas), in combination with theoretical models and simulations, to read the formation histories of these galaxies. • Objectives: • measure the incidence of slow and fast rotators, decoupled cores, stellar population gradients, cold gas, etc. in a volume-limited sample • understand the relative importance of dissipational / -less processes, major vs. minor mergers, gas accretion, environment, etc. in the formation of the various kinds of early-type galaxies • fit all of this information into its cosmological context

  5. A Multifaceted Approach to Galaxy Formation • Optical spectroscopy (SAURON on WHT) • Photometry multi-bands (INT, 2MASS, SDSS) • Single-dish CO survey of full sample (IRAM30m) • CO interferometry of detections with CARMA • HI maps of ~150 northern galaxies with WSRT (excl. Virgo) • Archival data (Chandra, XMM, GALEX, HST, Spitzer) • Simulationsof galaxy mergers • Semi-analytic modelingin the cosmological context

  6. Galaxy Classification (@ z=0) Hubble 1936 Kormendy & Bender 1996 But • Similar : • Ellipticity • V / s • S0 proposed as a ‘hypothetical’ class • Ellipticals classified via photometry

  7. Fast rotators Slow rotators λR=0.1 Emsellem et al., 2007

  8. The Red Sequence ( view) Slow Rotator • Wealth of kinematic structures • Most (>60%) early-type galaxies have ionised gas • Trends but no 1/1 relation with a4, cusp slope • Fast Rotators • Oblate systems (with bars) • Anisotropy vs flattening • Disks with lower central a/Fe • Slow Rotators • More spherical, mildly triaxial • All have kpc-sized KDCs • KDCs : no a/Fe enhancement Fast Rotator anisotropy Isotropy

  9. Competition between e.g.: • Gas-rich mergers or gas accretion: lR • Dissipationless mergers: lR • Baryonic angular momentum • expelled outwards in slow rotatorsEmsellem et al. 2007 lRversus Mass Slow Fast RED lR U - B BLUE MASS Log (Mass)

  10. The Next Step  A Complete Survey • Need volume-limited sample  To understand the distribution of Fast & Slow Rotators  To determine the relative fraction of wet / dry mergers  To provide strong low-z constraints on simulations  To understand the role of SF and feedback

  11. ATLAS3D  Observe a complete volume-limited sample of ETGs Atlas3D sample • MK < -21.5 • D < 41 Mpc • |δ– 29| < 35º • |b| > 15º • Subset of E / S0s • “No spiral structure” • (SDSS/DSS2) •  265 galaxies Red Blue

  12. Data are there…

  13. Stellarkinematics I V sh3 h4

  14. Ionised Gas ((Sarzi et al 2006) • Detected in >70% (EW ~0.1 Å) • teameffortledbySarzi • At least 20% are starforming • Misalignmentdistributionconfirmingearly SAURON one Gas VelocityMaps

  15. Molecular Gas ≡ CO • IRAM 30m single-dish data (team effort led by Bureau & Young) • 90% complete • detection limit M(H2)~ few 107 Msun • Preliminary results: 20% detection rate. • Same detection rate in Virgo and field galaxies! • CO interferometry: • Survey of detected galaxies with CARMA has been proposed (joint with UC Berkeley) • Very high resolution cases with PdB?

  16. CO detections in early-type galaxies in the Virgo Cluster (ROSAT PSPC: Bohringer et al 1994) CO no CO What is the effect of the cluster environment on the H2 content of early-type galaxies? Not much (preliminary) So are the S0s just stripped spirals? Or where did that molecular gas come from?

  17. CO maps: reading the past and the future • From the gas vs stellar angular momentum we hope to distinguish internal origin (stellar mass loss) vs external origin (accretion/merger?) • … and to quantify the role of gas in the formation of internal substructures. • Gas maps can give the star formation efficiency - for comparisons with spirals and with theoretical models.

  18. Neutral gas ≡ HI • WSRT observations(teameffortledbyMorganti, Oosterloo, Serra) •  100 galaxies (mostlyfieldgalaxies) • 25 on-going (40 nightsallocated) • largest/mostuniformdatabase of early-typegalaxies NGC 2481 NGC 2859 Tidalinteraction OLR ring

  19. Modeling & Simulations • Simulations of Mergers(teameffortledbyBournaud & Bois) •  Library of binary / multiplemergers at highresolution V field Binary 1:1 merger – 6 106particles / comp. / galaxy

  20. Simulations of ETGs • Fast / Slowrotatorswith 1:1 merger… • Orbital angular momentumlR I V s I V s lR lR SlowRotator FastRotator Re Re

  21. From 66 galaxies From SAURON

  22. To ATLAS3D • To 203 galaxies

  23. Semi-Analytical Modelling& the cosmological context • Constraining the main formation/evolutionprocesses • SAM: Team effort led by Khochfar • Simulations in cosmologicalcontext: Team effort led by Naab Nfast / Ntotal

  24. Star formation History • Towardsage, metallicity and a/Fe • Team effort led by McDermid, Kuntschner, Falcon-Barroso, Davies Slow rotators Fast rotators

  25. Revisiting the V/σ diagram Use new formalism for integral-field kinematics Binney 2005 anisotropy Isotropy Diagram for the whole sample Anisotropy trend from 25 Models Cappellari et al., 2007 • Fast-rotators:family of oblate systems • Slow-rotators:distinct - likely triaxial

  26. Gas vs Age

  27. lR: radial profiles FR have high and rising lR SR have quite flat or decreasing lR Emsellem et al., 2007

  28. Kuntschner et al. 2008 Finding inner disks  V [/Fe] [Z/H] Age      Log (R/Re) Log (R/Re) Log (R/Re) Log (R/Re)

  29. What about the other KDCs ? V [/Fe] [Z/H] Age      Log (R/Re) Kuntschner et al. 2008

  30. NGC2974 NGC4552 NGC3414 NGC4473 NGC4621 NGC5813 NGC5846 NGC5845 BH-σ update Tremaine et al. 2002 M87 Ferrarese & Ford 2005 • State-of-the-art models • Typical formal error 30-50% • Internal Structure • Use weighted σe from integral-field Cappellari et al. in prep.

  31. The Next Step ? The SAURON Survey • Complex biases due to selection: (ε,MB), (E,S0) • Quantitative comparison with simulations problematic Jesseit et al. in prep Cox et al. 2006

  32. GenericSimulations • Importance of resolution • lRprofiles •  Needfor 2563 5123 2563 1283 lR Re Re Re

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