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Red Sequence formation ages

Red Sequence formation ages. Marc Balcells Collaborators GOYA Team : Carmen Eliche-Moral, David Crist óbal, Lilian Domínguez, Mercedes Prieto, Marc Vallbé, Carlos López Tenerife Nbody Team : Carmen Eliche-Moral, César González-García, Alfonso L. Aguerri Instituto de Astrofísica de Canarias.

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Red Sequence formation ages

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  1. Red Sequence formation ages Marc Balcells Collaborators GOYA Team: Carmen Eliche-Moral, David Cristóbal, Lilian Domínguez, Mercedes Prieto, Marc Vallbé, Carlos López Tenerife Nbody Team: Carmen Eliche-Moral, César González-García, Alfonso L. Aguerri Instituto de Astrofísica de Canarias MAGPOP La Palma Workshop

  2. Summary • Major epoch of E galaxy formation: 1 < z < 2 • Ancestors of L* ellipticals stopped making stars at z~1.5 (9 Gyr ago) • Galaxies with centrally-peaked profiles (“with bulges”), 0.3 < z < 1.0: • Define a Red Sequence, of Bulge Colors • Galaxies without ~exponential profiles: color distribution does not show a Red Sequence • Galaxies with bulges: Integrated colors define a Red Sequence as well • Redder bulges live in redder galaxies, with redder disks • We don’t find red-old bulges surrounded by forming, blue disk • Minor mergers make bulge grow from disk material MAGPOP La Palma Workshop

  3. Work in preparation for GOYA survey • Major study of high-z galaxy populations • Using upcoming EMIRNIR multi-object spectrograph on 10.2 m GTC • UFL, UCM, Toulouse, IAC • Guzmán, Gallego, Pelló, Balcells MAGPOP La Palma Workshop

  4. Upcoming GTC Science funds • “GTC Science ‘CONSOLIDER’ program • Spanish ministry of Science • 5 yr, 5 Meuro • Postdoc opportunities to be advertised ~2007 January • Covering most science large programs with GTC • GOYA high-z NIR spectroscopy, EMIR • OTELO narrow-band tunable filter deep survey, OSIRIS • Massive stars in MW, OSIRIS, EMIR • Brown dwarfs, EMIR MAGPOP La Palma Workshop

  5. 0.5 square degree K=J=22 AB mag UBVRI=26 AB mag Fields: Groth GOODSN V0226 (COSMOS-10h) Other, smaller fields (excluded from spectroscopic survey?) SA68 SIRTF-FLS Coppi GOYA Photometric Survey MAGPOP La Palma Workshop

  6. Blue band: power-law, up to B~25 NIR band: break at K~17.5 Galaxy number counts - Groth strip Eliche-Moral et al (2006a) Cristóbal-Hornillos et al (2003) MAGPOP La Palma Workshop

  7. Features in counts = features in LF • Goal is to reproduce entire distribution of counts U,B,K • K counts change slope • U,B counts featureless power law • Features in number counts = feature in LF Euclidean: MAGPOP La Palma Workshop

  8. Modeling • Evolution of local LF back in time • SDSS LFs, morphologically dependent Nakamura et al. 2003 • Ellipticals, early spirals, late spirals, Irregulars • No disappearing dwarf populations • Observationally-motivated model ingredients • Number evolution ~(1+z)2.0 • Extinction AB=0.6 (face-on), all galaxy classes • Salpeter IMF • Metallicities: Solar(E,Sa-b), 0.2solar(Sd), 0.1solar(Ir) • Standard star formation histories • Instantaneous for ellipticals • Exponentially decaying for Spirals, Irregulars • Only ‘free’ parameters: formation epoch for each galaxy class MAGPOP La Palma Workshop

  9. Simultaneously reproduce number counts in Groth, U, B, Ks Eliche-Moral et al (2006a) Wide ranges - 18 mag in B, 10 mag in Ks Late zf=1.5 for ellipticals gives knee in Ks counts Ks~17.5 Extinction prevents bump from appearing in B Number evolution gives right overall slope Reproduce B,K counts MAGPOP La Palma Workshop

  10. Limits on model parameters • zf constrained for E. zf>2.5 does not work. • For S0a-Sb, zf=1.5 to zf=4 good fit • Extinction essential • AB=0.2 does not work • Mergers essential • Otherwise, need to introduce a disappearing population • Moderate variations of rate are OK • IMF, metallicities: little effect • Instantaneous, SSP for ellipticals necessary MAGPOP La Palma Workshop

  11. 9 Gyr broad agreement with other age determinations • z=1.5: lookback-time 9 Gyr • No major conflict with Population diagnostics • stellar populations of cluster ellipticals: age~12 Gyr Vazdekis • Field ellipticals, populations younger than 8 Gr Heavens et al 2005 Schiavon et al 2006 • Distant Cluster Survey, CMD scatter: zform = 2.2 - 2.6 • Taking ‘progenitor bias’ into account, ellipticals zform=2 Franx & Van Dokkum 1996 • DEEP2 “picture”: RS starts at z=1.5 Michael Cooper, today • GOODS-K20 morphology: E’s disappear by z=2 Cassata et al. (2004) • But is there a selection effect? • MK*=-23.6 has KS=20.6 at z=2 MAGPOP La Palma Workshop

  12. Duration of the elliptical formation epoch • Model captures major growth phase of red sequence, 1<z<2 • DRGs (Distant Red Gals) - evolved-SED galaxies 2<z<4 Franx et al 2003; Daddi et al. 2004; de Mello et al. 2004 • Model can accommodate a fraction of evolved galaxies at z>2 • Cluster ellipticals?; ours are field population. Many have star formation • How much z<1 migration to red clump can be expected from data? • 30% OK • 50% (Bell et al. 2004; Faber et al 2005) probably OK, pushing it. MAGPOP La Palma Workshop

  13. Physical processes? • NCMOD did its best to reproduce the appearance of a red population at z~1.5 • Seeing the formation of red, early types by mergers of Spirals? • Stars formed before • Merger-driven quenching of star formation • Seeing the epoch when most halos reached Mvir=6e11 Msun ? Birmboim & Dekel 03, Dekel & Birnboim 06 Cattaneo et al 2006 • Mergers @ z<~1.5 involve more massive halos that shock the gas and inhibbit subsequent star formation? • Merger models not scale-free once gas cooling, heating is included • Process probably related to morphological transition at z=1.5 Conselice 04 MAGPOP La Palma Workshop

  14. Inner structure of Red-Sequence galaxies • Field galaxies, z=0.2 - 1.0 (Groth strip) • Diameter-limited. Separate in two classes • With ~exponential surface brightness profile • With central surface brightness excess (“bulge galaxies”) MAGPOP La Palma Workshop

  15. Colors of bulges and disks • “Bulge” colors: on minor axis of inclined galaxy, choose bluest • Disk colors: on face-on galaxies • K-corrections (UBVIJK) • COSMOPACK tool Balcells & Cristóbal 2002 • Completeness analysis • R>1.4” at z=0.8 matches large NGC spirals MAGPOP La Palma Workshop

  16. Inner structure of Red-Sequence galaxies • Find: • “Bulge galaxies” have a Red Sequence in bulge colors (R=0.2” ~ 1.5 kpc) • “Bulge galaxies” have Red Global colors U-B rest-frame TOTAL colors, bulges vs no-bulges U-B rest-frame BULGE colors, bulges vs no-bulges MAGPOP La Palma Workshop

  17. Inner structure of Red-Sequence galaxies • This means: • Disk galaxies in Red Sequence need to have a photometric bulge • Galaxies with Red bulges at z=0.8 had red disks at z=0.8 • Red bulges surrounded by a blue disk of active star formation are not seen in Groth up to z~0.8 • B-R rest-frame nuclear colors strongly correlate with integrated galaxy colors • Same as z=0 disk galaxies • Peletier & Balcells 1996 • For galaxies with and without bulges • Domínguez & Balcells 2007 MAGPOP La Palma Workshop

  18. Cosmic Variance - GOODSN • Mimicing analysis in GOODS-N • Same red sequence in GOODSN ! • Previous claim for NO RED SEQ IN GOODS, due to an zeropoint error ….. • (see our Abstract in Abstract book). MAGPOP La Palma Workshop

  19. Minor mergers • Accreting disk satellites onto disk galaxies • TF scaling primary-secondary • Result: • Little satellite mass deposition in bulge • Inward transport of disk matter • Bulge growth out of disk material triggered by accretion Eliche-Moral et al 2006b MAGPOP La Palma Workshop

  20. Accretion-driven B/D growth • B/D increases with each accretion, together with Sersic index of bulge. Even if no satellite matter reaches the center ! Eliche-Moral et al 2006b MAGPOP La Palma Workshop

  21. Summary • Major epoch of E galaxy formation: 1 < z < 2 • Ancestors of L* ellipticals stopped making stars at z~1.5 (9 Gyr ago) • Galaxies with centrally-peaked profiles (“with bulges”), 0.3 < z < 1.0: • Define a Red Sequence, of Bulge Colors • Galaxies without ~exponential profiles: color distribution does not show a Red Sequence • Galaxies with bulges: Integrated colors define a Red Sequence as well • Redder bulges live in redder galaxies, with redder disks • We don’t find red-old bulges surrounded by forming, blue disk • Minor mergers make bulge grow from disk material MAGPOP La Palma Workshop

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