Massive galaxies at z 2 from k20
This presentation is the property of its rightful owner.
Sponsored Links
1 / 38

Massive galaxies at z ~ 2 from K20+ PowerPoint PPT Presentation

  • Uploaded on
  • Presentation posted in: General

Massive galaxies at z ~ 2 from K20+. Preamble: (Cimatti, Daddi, Fontana, Arimoto, GOODS, GRAPES, COSMOS ) Looking at z~2 massive galaxies gives us more leverage than looking at z~1 ✰ as their predicted abundance and properties (e.g. Passive vs. starbursting)

Download Presentation

Massive galaxies at z ~ 2 from K20+

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript

Massive galaxies at z 2 from k20

Massive galaxies at z ~ 2 from K20+

Preamble: (Cimatti, Daddi, Fontana, Arimoto, GOODS, GRAPES, COSMOS )

Looking at z~2 massive galaxies gives us more leverage than looking at z~1

✰ as their predicted abundance and properties (e.g. Passive vs. starbursting)

are most critically dependent on theoretical model *assumptions, *algorithms and *parameters →allow to narrow down our model shopping list.

Fontana et al.


A Renzini, STScI, September 27, 2004

The local mass function from the sdss

The Local Mass Function (from the SDSS)

et al. (2003)

In the local universe:

Among the MMGs the old

passively evolving, early-type galaxies outnumber the starforming galaxies by

more than a factor ~10

The high z tail in the k20 sample

The High-z Tail in the K20 Sample

K<20 galaxies at z > 1.6:

~ 0.0 predicted by SAMs

32 observed in the the K20 sample

(apparent agreement with PLE models)


Cimatti et al. 2002


The nature of the k 20 z 1 6 galaxies 1 the star forming galaxies

The Nature of the K<20, z>1.6 galaxies1. The Star-Forming Galaxies

Daddi et al. (2004)

The k 20 z 2 starforming galaxies

The K<20, z≈2 starforming galaxies

Coadded spectra of 5 best

S/N galaxies

(de Mello et al. 2004).

More stronglined than LBGs

both for ISM and photospheric absorptions

➔ >~solar metallicity

which along with:

● M*>1011M⊙

● SFR > ~ 100 M⊙/yr

● Strong clustering ➔

Likely progenitors of local

ellipticals and big bulges

2 the passively evolving galaxies

(The Highest redshift ellipticals)

2. The Passively Evolving Galaxies

Cimatti et al. (Nature, July 8, 2004)

ACS/GOODS images

Coadded VLT spectra

→ zF > 2.5-3

The mg uv feature a key to hi z passive galaxies

The MgUV Feature: a key to hi-z passive galaxies

First used by Dunlop/Spinrad et al '96; Cimatti et al '04; McCarthy et al. '04)

Passively evolving galaxies cont

Passively Evolving galaxies (cont.)

In red LBDS 53w091 (z=1.55) Blue=average of the 4 gals.

1 Gyr 3Gyr

0.5 Gyr

z=1 old EROs


SDSS <z>=0.5




The 4 galaxies in real color

The 4 galaxies in real color

GOODS ACS BViz images

Old galaxies at high redshift

Old galaxies at high redshift

In the K20/GOODS field (32 □)

Passive galaxies with R-K>6,

z>1.5, K<20:

4 objects with zspec

3 objects with zphot

7 objects in total

In the currently “best” semi-analytic model

(Somerville 2004): Mock catalog for a

whole GOODS field (160 □):

Only one object with the same


35 expected scaling from the K20

The acs goods morphologies

32 K20 galaxies at z>1.4 with deep z-band ACS imaging

The ACS/GOODS Morphologies

S=Starforming ➔ mergers, starbursts

P=Passively evolving ➔ Elliptical and Bulge-dominated galaxies

Some inferences so far

Some Inferences (so far)

●Massive (M*>1011M⊙) galaxies appear to be in place at z ~ 2 in much

greater number than predicted by most CDM Simulations

Models with strong SN/AGN feedback do better (Nagamine et al. 2001; Granato et al. 2004) [Anti-hierarchical galaxy assembly!]

While at z=0 most “most massive galaxies” are passively evolving, old ellipticals, by z~2 passive and active star-forming galaxies coexist in nearly equal number

☹Limitations of the K20 survey:

✈relatively small area (prone to cosmic variance)

✈relatively shallow (K<20)

Post k20 go wider go deeper focus on z 2

Post-K20: go wider, go deeper,focus on z~2

Daddi et al. (2004)

The BzK criterion for

selecting BOTH starforming

(reddening independent!) and passively evolving galaxies at 1.4<z<2.5

Calibrated on the K20, GOODS, and GDDS


⇦K20/GOODS data only shown here.

Massive galaxies at z 2 from k20

Why the BzK criterion works

Daddi et al. (2004)

BC03 models with various ages, SF histories,

and reddening:

Nice agreement with the

K20 empirical findings


Cont. SF

SFR ~ e(-t/τ)


Bzk vs lbg ugr selected galaxies

BzK- vs. LBG UGR-selected Galaxies

A preliminary comparison: K20 BzK sample vs UGR sample (Steidel et al. 2004)

UGR Objects (R<25)

E(B-V) < 0.3

<SFR> =~50 M⊙/yr

~9 objects/□'

~2/3 of the BzK+UGR

Star Formation Rate

@ z = 2

Misses highly reddened objects

~ 9 Objects/□'

~2/3 of the BzK+UGR

Star Formation Rate

@ z = 2

Misses highly reddened objects

K20 BzK Objects (K<20)

<E(B-V)> > 0.3

<SFR> = ~ 200 M⊙/yr

~1 Object/□'

~1/3 of the BzK+UGR

Star Formation Rate

@ z=2

Misses objects with K>20

Misses Objects wit


~ 1 Object/□'

~1/3 of the BzK+UGR

Star Formation Rate

@ z = 2

Misses objects with K>20



drwx------ 31 alvio alvio 4096 Feb 20 12:15 .

[[email protected] alvio]$

Going deeper the gmass project

Going deeper: the GMASS project

(Also called the K21 project)

VLT/FORS2 ultradeep spectroscopy (~30 hours integration per mask) over

the UDF/GOODS-South field. PI A. Cimatti, Co-Is as usual

Scheduled for September-November 2004.

The selected targets on the BzK diagram

All targets with:

K>20 (average 21.2)

(4.5)AB<23.5 (FromSpitzer/GOODS)

Perhaps the first Spitzer-selected


Going deeper the udf grapes sample

Going Deeper: the UDF+GRAPES* Sample

Selecting candidate passively evolving galaxies at z>1.4 from the

UDF field (Bz) & GOODS (K) with

the BzK plot. ACS/GRISM spectra from the GRAPES project.

Daddi et al. 2004 (in prep)

Targets down to K=21.1




*Malhotra et al. 2004

Acs cutouts acs grism spectra

ACS Cutouts & ACS/GRISM Spectra

The MgUV Feature as a function of SSP age

and for Continous SF

+ E(B-V)=1.2

Redshifts identified by the MgUV Feature

agree with photo-z's

Acs nicmos morphologies

ACS&NICMOS Morphologies

Sersic index in z



n= 4.7






Passive or active

Passive or Active?

Object #4950 @ z=1.55

Masses and mass densities

Masses and Mass Densities

Typical (stellar) masses of these galaxies are ~ 0.5-2 1011M⊙

The 6 passively evolving galaxies at 1.4<z<2.0 with M* > ~1011M⊙correspond to 20-40% of the number density of such galaxies at z=0.

Assuming ro= 10 Mpc for their correlation length the 1 range

becomes 10-80% (!) COSMIC VARIANCE dominates


Going wider bzk selected galaxies over 1000

Going Wider: BzK-selected galaxiesOver ~ 1000 □

ESO/SUBARU Collaboration:Cimatti, Daddi, Renzini, + Arimoto, Ikuta, Kong,

Broadhurst, Pozzetti et al. Onodera, et al.

K-band (<20.2) from NTT, Bz bands from SuprimeCam

Objects observed with

VIMOS, February '04

❍ Blue grism, R=200

 Red grism, R=600

Reductions in progress

Work in progress

Work in Progress

Typical VIMOS/Blue grism spectra of BzK-selected galaxies (R=200)

Z=2.360 B=24.4

Z=1.565 B=24.3

Z = 1.822


Z=2.200 B=24.3

Goods cosmos


GOODS: 160 + 160 □'COSMOS: 2 □° ACS Equatorial Field

Goal: ~90,000 redshifts w/ VLT/VIMOS

GOODS-South: To be proposed ... + Magellan/IMACS

~6000 redshifts from the VLT + whoever may like to join with other

~2000 released, the rest next fall telescopes





as a function

of redshift

and LSS


by 2006-07.

Cosmos targets bzk ugr selected

COSMOS Targets BzK+UGR selected

Red, Blue, Black: (K)<0.2

2000; 20,000; 100,000

(BzK-selected galaxies)

Yellow,Cyan: (K)>0.2


(UGR-selected, à la Steidel)

Yellow+Blue: VLT/VIMOS/LR-blue


Red: Magellan/IMACS

Starforming, 1.4<z<2.5

Passive, z>1.4

Galaxies, z<1.4


Data: Bz (SUBARU), K (NOAO, IfA), U (CFHT)

from B. Mobasher catalog

Cosmos targets

COSMOS Targets

Bottom line: all selection

criteria are +/- biased:

the BzK+UGR selection

is the most un-biased

criterion we were able to



ACS (Scoville),

SUBARU (Taniguchi)

CFHT (LeFevere)

VLT (Lilly)

Magellan (McCarthy)

XMM (Hasinger)

Galex (Rich)

VLA (Schinnerer)






 Different CDM Models tuned to match some z=0 observable diverge

widely by z=2.

 By z=2 the massive galaxy mix is ~50-50 passive and starbursting

 Current data favor an early build up of galactic spheroids, with the

more massive ones completing their star formation ahead of the

less massive ones (seemingly “anti-hierarchical”, “downsizing”)

 Fully explored fields (< 100 □) are still dominated by cosmic

variance. But ..................

2005 2007 full mapping of galaxy evolution up to z 6 7

2005-2007 (~full) Mapping of Galaxy Evolution up to z = 6.7



Ellipticals in clusters and field look much the same

Ellipticals in clusters and fieldlook much the same

Bernardi et al. (2003): ~9000

ellipticals in the SDSS sample.

No appreciable trend of the

stellar population content with

local density.

“Field” ellipticals less than

~1 Gyr younger than cluster


Searching for the high z precursors of the mmgs at z 0

Searching for the high-z Precursors ofthe MMGs at z=0

By and large, this is ~equivalent to searching for the precursors of elliptical


@ z=1: Passively evolving “EROs” (R-K>5) in (almost) enough number

Beyond z=1:

■Up to which redshift passively evolving galaxies can be found?

■Given that the bulk of stars in ellipticals formed at z>~3:


Searching for high z massive galaxies the k20 project and beyond

Searching for High-z Massive Galaxies(the K20 Project, and Beyond)

1999: in absence of a better criterion, pick near-IR bright galaxies as best

proxies to MMGs:

i.e. Select for VLT spectroscopy K 20 galaxies ➔ the “K20 project”

PI: A. Cimatti, Co-Is: E. Daddi, A. Fontana, L. Pozzetti, A. Renzini,

G. Zamorani, T. Broadhurst, M. Mignoli, et al.

 Deep VLT Spectroscopy of 546 K 20 objects, over two fields (52 □)

● Now  92% complete ( 95 % over the subfield included in the GOODS field)

1999: in absence of a better criterion, pick near-IR bright galaxies

i.e. Select for VLT spectroscopy K 20 galaxies ➔ the “K20 project”

PI: A. Cimatti, Co-Is: E. Daddi, A. Fontana, L. Pozzetti, A. Renzini,

G. Zamorani, T. Broadhurst, M. Mignoli, et al.

The redshift distribution of the k 20 sample of galaxies

The Redshift Distribution of the K<20 Sample of Galaxies


Pure Luminosity Evolution (PLE) Models apparently do better than CDM (<2002) Semianalytic Models (SAM)(Cimatti et al. 2002)



The stellar masses of k20 galaxies

The Stellar Masses of K20 Galaxies

Stellar masses derived from either color (R-K) (MA)

or SED (UBVRIzJHK) fits

(BF) and the K magnitude.

● Old Passive (Early type)

❍ Early + Emission line

 Photo-z only

X Star forming

The evolution of the galaxy mass function

The Evolution of the Galaxy Mass Function

Fontana et al. (2004)

□ BF Masses

∇ MA Masses

❍ zspec only

Color code:

Bad fit

Poor fit Fair fit

Good fit

Menci et al '02,'04 Nagamine et al '01 Cole et al. '00;Granato et al. '04

(Salpeter IMF) (Gould IMF) Somerville et al. '04a, '04b

(Kennicutt IMF)

Massive galaxies at z 2 from k20

The K20 vs the Munics Mass Function up to z=1.2

(Very nice agreement)

Drory et al. (2004)

1 □o ; K<19.5;

mostly photo-z's

The build up of stellar mass through cosmic time

The Build Up of Stellar MassThrough Cosmic Time

⇧ is my preferred value from

the fossil evidence (mass and formation redshift of local spheroids), i.e. >30% of the stellar mass done by z=3

(Renzini 1998, 1999)

From Fontana et al. (2004)

Baryon to star conversion as a function of galaxy mass

Baryon-to-star conversion as a function of galaxy mass

Available baryons from CDM

simulation assuming cosmic share (b/m)

Two Main Points:

 There are enough massive DM halos to account for the massive galaxies we see

(No fundamental failure of the DM paradigm).

 Strong mass dependence of the baryon-to-star conversion efficiency (many interesting ramifications ... ).


  • Login