Red Sequence formation ages

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

2
Summary

• Major epoch of E galaxy formation 1 lt z lt 2
• Ancestors of L ellipticals stopped making stars
  at z1.5 (9 Gyr ago)
• Galaxies with centrally-peaked profiles (with
  bulges), 0.3 lt z lt 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 dont find red-old bulges surrounded by
  forming, blue disk
• Minor mergers make bulge grow from disk material

3
Work in preparation for GOYA survey

• Major study of high-z galaxy populations
• Using upcoming EMIR NIR multi-object spectrograph
  on 10.2 m GTC
• UFL, UCM, Toulouse, IAC
• Guzmán, Gallego, Pelló, Balcells

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

5
GOYA Photometric Survey

• 0.5 square degree
• KJ22 AB mag
• UBVRI26 AB mag
• Fields
• Groth
• GOODSN
• V0226
• (COSMOS-10h)
• Other, smaller fields (excluded from
  spectroscopic survey?)
• SA68
• SIRTF-FLS
• Coppi

6
Galaxy number counts - Groth strip

• Blue band power-law, up to B25

• NIR band break at K17.5

Eliche-Moral et al (2006a)
Cristóbal-Hornillos et al (2003)
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
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 (1z)2.0
• Extinction AB0.6 (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

9
Reproduce B,K counts

• 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 zf1.5 for ellipticals gives knee in Ks
  counts Ks17.5
• Extinction prevents bump from appearing in B
• Number evolution gives right overall slope

10
Limits on model parameters

• zf constrained for E. zfgt2.5 does not work.
• For S0a-Sb, zf1.5 to zf4 good fit
• Extinction essential
• AB0.2 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

11
9 Gyr broad agreement with other age
determinations

• z1.5 lookback-time 9 Gyr
• No major conflict with Population diagnostics
• stellar populations of cluster ellipticals
  age12 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 zform2
• Franx Van Dokkum 1996
• DEEP2 picture RS starts at z1.5
• Michael Cooper, today
• GOODS-K20 morphology Es disappear by z2
• Cassata et al. (2004)
• But is there a selection effect?
• MK-23.6 has KS20.6 at z2

12
Duration of the elliptical formation epoch

• Model captures major growth phase of red
  sequence, 1ltzlt2
• DRGs (Distant Red Gals) - evolved-SED galaxies
  2ltzlt4
• Franx et al 2003 Daddi et al. 2004 de Mello et
  al. 2004
• Model can accommodate a fraction of evolved
  galaxies at zgt2
• Cluster ellipticals? ours are field population.
  Many have star formation
• How much zlt1 migration to red clump can be
  expected from data?
• 30 OK
• 50 (Bell et al. 2004 Faber et al 2005) probably
  OK, pushing it.

13
Physical processes?

• NCMOD did its best to reproduce the appearance of
  a red population at z1.5
• 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
  Mvir6e11 Msun ?
• Birmboim Dekel 03, Dekel Birnboim 06
• Cattaneo et al 2006
• Mergers _at_ zlt1.5 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 z1.5
• Conselice 04

14
Inner structure of Red-Sequence galaxies

• Field galaxies, z0.2 - 1.0 (Groth strip)
• Diameter-limited. Separate in two classes
• With exponential surface brightness profile
• With central surface brightness excess (bulge
  galaxies)

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
• Rgt1.4 at z0.8 matches large NGC spirals

16
Inner structure of Red-Sequence galaxies

• Find
• Bulge galaxies have a Red Sequence in bulge
  colors (R0.2 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
17
Inner structure of Red-Sequence galaxies

• B-R rest-frame nuclear colors strongly
  correlate with integrated galaxy colors
• Same as z0 disk galaxies
• Peletier Balcells 1996
• For galaxies with and without bulges

Domínguez Balcells 2007

• This means
• Disk galaxies in Red Sequence need to have a
  photometric bulge
• Galaxies with Red bulges at z0.8 had red disks
  at z0.8
• Red bulges surrounded by a blue disk of active
  star formation are not seen in Groth up to z0.8

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).

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
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
21
Summary

• Major epoch of E galaxy formation 1 lt z lt 2
• Ancestors of L ellipticals stopped making stars
  at z1.5 (9 Gyr ago)
• Galaxies with centrally-peaked profiles (with
  bulges), 0.3 lt z lt 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 dont find red-old bulges surrounded by
  forming, blue disk
• Minor mergers make bulge grow from disk material