Conference Summary

Richard Ellis (Caltech)

ITALIA

DEUTSCHLAND

SCHWEIZ

ÖSTERREICH

View from Top Mountain Star

Galaxy Formation – Is the End in Sight?

Madau et al 1996, Baugh et al 1998

Zeldovich (1978): “One can be pretty sure that the problem of galaxy formation will be solved in the 1980’s”

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1990’s: unwarranted confidence from theorists & observers: extended SF histories was an early prediction of CDM models matching optical data only

LESSONS FROM THE PAST

Galaxy Formation Issues

• Do we have a complete census of star formation activity and baryon content at all epochs? - key role of multi-wavelength techniques
• How did the Hubble Sequence emerge at z<1 from the varied active and irregular sources at z > 2? What are the physical processes involved? Are the detailed models correct?
• z > 6 the final frontier: did early galaxies reionize the Universe and what early feedback processes shape the later assembly history?

Challenges:

• Assumed physics & is it time invariant? (IMF, stellar pops, modes of star formation, dust laws etc)

Disclaimer

58 talks × 30 slides = 1740 slides

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AND 54 posters

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All carefully digested, rationalized, inter-compared with results in the literature to give a “lucid, crisp, holistic view of our present understanding of the formation of galaxies…..”

What follows is a brief, personal, selection of key issues

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Apologies if your talk/poster (or even entire field!) is not mentioned

Theoretical Progress

• Two ways to interpret galaxy data

- numerical simulations involving gas dynamics (SPH, GRID..)

- semi-analytic models (SAM)

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• Both use stellar population modeling to match masses,colors, dust (Tonini, Henriques, Silva, Mentuch)

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• This conference: (Moore, Nagamine, Gonzalez, Somerville, Narayanan)

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• Complementarity of SPH and AMR simulations
• Claimed successes: cosmic SFH, local TF relation, morphologies of z~3 galaxies, origin of SMGs, AGN feedback

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• Controversies

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• Hydro: “AGN feedback overstressed in semi-analytic models”
• SAM – need top heavy IMF to explain SMG counts

Nagamine

Governato et al 2006

10^5 SPH particles in total, 500pc resolution

Better match with T-F.

Huge spheroid, disk is unresolved single phase cold gas

Reproducing Local Tully-Fisher Relation & Resolving Angular Momentum Problem

Moore

Desika Narayanan

SMGs form in Mergers

Narayanan, Hayward et al. 2009a

Chapman, Casey

Ways Forward: Velocity Fields with ALMA

Dec 15th 2009

Desika Narayanan Obergurgl

Davé et al 2009: Harassment

Narayanan et al 2009b: Major Mergers

Sub-millimeter Galaxies Are Dissipative Gas Rich Mergers

Neri et al. 2003, Greve et al. 2005,

Tacconi et al. 2006, 2008, Swinbank et al. 2009, Bothwell et al. 2009, Smail et al. 2010, Engel et al. 2010

Tacconi, Walter

Low Metallicity Gas in High z Radio SMGs?

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Chapman

Blain et al 2004 Ap J 611, 725

BLAST power spectra P(k,z)

Correlation length r₀

Clustering of SMGs?

Progress from BLAST and enlarged redshift samples

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Broadly consistent with earlier (noisy) estimates

Viera, Chapman, Halpern

20%(?) of SMGs may end up as massive DRGs?

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Not required that all DRGs form via one route

Hopkins (2004), Hopkins & Beacom (2005)

• complementary diagnostics
• standardized IMF, cosmology, extinction law, luminosity limit

Star formation rate per unit comoving volume

Cosmic Star Formation History

UV, [O II], Hα, mid-IR

Peak z~2-3

Redshift →

Nagamine

Optical-Lilly

Optical-Steidel

BLAST-IR Star Formation Rates. (Grey disks have MIPS photo-z contribution removed.)

Halpern

Nagamine

Sawicki & Thompson (2006)

Data at z~3-4 adequate test

Emergence of Hubble Sequence: Galaxy Demographics 0<z<3

Growing body of data at 1<z<3: formative period in galaxy evolution

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• Spectroscopic and photometric surveys (Le Fevre, Ilbert)
• Resolved dynamics of star forming galaxies (various)
• Mass-metallicity relation (Mannucci)

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Formation of red sequence at z~0 (Faber, Hudson)

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• Masses and colors of z~2-3 red galaxies (Henriques, Conselice)
• Evidence of star formation thresholds (Faber)
• Timescale of truncation and AGN feedback (Somerville, Faber)
• Morphology versus color (red disks)

Elmegreen et al 2009: Clumpy high redshift galaxies – chains, clusters etc.

Clumpy (10^8Mo), high star-formation rates, extended over ~10kpc radii

ACS images (Elmegreen et al)

Moore

The complex gas flows into a dark matter halo with a forming disk galaxy at a redshift z=3. R=temperature, G=metals and B=density. (Agertz, Teyssier & Moore 2009). One can clearly distinguish the cold pristine gas streams in blue connecting directly onto the edge of the disk, the shock heated gas in red surrounding the disk and metal rich gas in green being stripped from smaller galaxies interacting with the hot halo and cold streams of gas. The disk and the interacting satellites stand out since they are cold, dense and metal rich.

Moore

IFU Spectroscopy 1<z<1.5 (Daniela Vergani, poster)

Resolved Dynamics (~100 pc resn!) via Combination of Lensed Magnification and Keck Adaptive Optics

Jones et al (astro-ph/0910.4488)

6 lensed galaxies 1.7 < z < 3.1 (linear magnification ~8-10) revealing rotation in 5/6 cases

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Rotation would not be revealed without lensing magnification

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1 kpc = 0.13”

Mass – Metallicity Relation @ z~3

F. Mannucci

SINFONI data on LSD and AMAZE programs:

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Can argue z~3 is a formative period where most growth is in mass (with only modest increases in metal content).

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Subsequent evolution is mostly in metallicity

Massive Red Galaxies @ z=2 are Small!

SDSS

2 < z < 3

HST NIC2 sizes of a representative sample of z~2-3 red galaxies with M >10¹¹ M_◉: r_e~0.9 kpc

2-5 times smaller than comparably massive z~0 ellipticals!

Growth in size but not mass?

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half-light radius

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van Dokkum et al (2008) (also Conselice)

Reliability of Stellar Masses?

Henriques

CB07 mass --TP AGB stars included

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BC03 mass -- no TP AGB stars

939 z~4 LBGs in GOODS-S

• Inclusion of TP-AGB stars has little effect on UV- optical SED & inferred stellar masses
• Few catastrophic failures refer to cases with marginal IRAC detections

Effect of TP-AGB Stars

Stark et al, in prep

Dynamical Masses: DEIMOS vs LRIS-R?

Efficiencies from June LRIS-R run (Drew Newman)

DEIMOS G830/9000

LRIS-R 600/1μm

Dynamical Masses & Fundamental Plane 1<z<1.7

Newman, RSE et al (in prep)

• Dynamical masses for red spheroidals in era 1<z<1.7
• Keck: LRIS-R m(AB)<23.5; 8-12 hr integrations

Evol in FP

8

9

11

Red sequence

Blue cloud

10

12

11

9

8

Flow through the color-mass diagram for “central” galaxies

Faber et al. 2007

Quenching band

0

2

4

6

8

Redshift, z

Log (M_halo/M_◉)

15

14

13

12

11

10

9

A schematic model of average halo mass growth

SFR = f(M_halo, z)

M_crit

• Stellar masses from Palomar K-band photometry for a large (8000g) spectroscopic sample (Keck DEEP2)
• The sites of star formation appear to shift from including high-mass galaxies at early epochs (z~1-2) to only lower-mass galaxies at later epochs.
• Using rest-frame U-B color as a SF discriminant, stellar mass functions reveal a threshold stellar mass above which SF is somehow quenched

Bundy et al Ap J 651, 120 (2006)

log stellar mass →

0.4<z<0.7

0.5<z<1

1<z<1.4

Threshold Mass for Quenched Star Formation

“Quasar” mode

(eg. Granato et al., 2004, Springel et al 2005)

Radio

X-rays

Temperature

“Radio” mode feedback

(eg. Croton et al 2006, Bower et al 2006 Okamoto et al 2007)

AGN Feedback

Quiescent hot gas accretes onto central BH creating outflow (radio jet) which suppresses cooling flow and associated SF: may explain downsizing

Supermassive BH grows via merger of two coalescing systems; cold disk gas is driven onto the BH: may explain tight BH mass - bulge relation

• Reproducing local B_J and K luminosity functions
• Switching “radio” feedback off leads to a population of very bright galaxies formed in cooling flows
• But position of the LF break is set by the division between rapid and hydrostatic cooling haloes
• But does this model reproduce evolving mass function and hence the production rate of quiescent early-types?

K-band

B_j band

Popular Models of AGN Feedback

M_K

M_BJ

Bower et al (2006)

importance of different FB modes is mass-dependent:

• SN-driven winds remove baryons from small-mass halos
• some process(es) prevent cooling in large-mass halos (radio jets, clumps, conduction, cosmic ray pressure?)

rss, Hopkins, Cox, Robertson & Hernquist 2008

z=0

• Theorists are finally putting their products on the web
• At last observers can make their own judgements on how well CDM really works!
• `Past light cone’ treatment of MS permits direct comparison with DEEP2/Palomar stellar mass functions
• Comparison shows AGN feedback prescription too effective at high z: fewer blue galaxies than observed

Stringer et al MN 393, 1127 (2009)

Millenium Simulation + AGN Feedback

1 < z < 1.4

0.7 < z < 1

0.4 < z < 0.7

But do AGN live in quenched/quenching galaxies?

Nandra et al. 2006

And Is Morphological Evolution Synonymous with Color Transformation?

Red passive disks in COSMOS

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• significant fraction of red sequence are disks, particularly at low masses

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• red disks are more bulge-dominated than higher z star-forming disks

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• a key intermediate phase in the transition to present day spheroidals

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Bundy et al 0912.1077

Redshift🡺

Log fraction of Red Sequence

today

Big Bang

`First light’

THE FINAL FRONTIER: Z > 7 GALAXIES

Lyman break galaxies:

Rest-frame UV continuum discontinuity

High Redshift Star Forming Galaxies

Lyman alpha emitters:

Located via narrow band imaging

z=5.83

Eyles et al (2005): to produce this mass since z~10 required 5-30 M_◉ yr^-1 comparable to the ongoing SFR (6-20 M_◉ yr^-1) so should see earlier examples if unobscured

HST

IRAC

VLT

Balmer break

A modest 85cm cooled telescope can see the most distant known objects and provide crucial data on their assembled stellar masses and ages

The Spitzer Revolution: Stellar Masses

age (yr)

mass (M_◉)

SMB03-1: z_spec=5.83 IRAC(3.6μm)=24.2 (AB) stellar mass = 3.4 10¹⁰ M_◉ age > 100 Myr

z = 7

t = 50 Myr

t = 100 Myr

t = 300 Myr

t = 500 Myr

t = 600 Myr

t = 800 Myr

Balmer Break as Age Indicator

Age is degenerate with star formation history but can infer time-averaged star formation rate and compare this with actual on-going star formation rate

Stellar Mass Density

completeness limit

V-drops z~5

i-drops z~6

z~4 mass fn.

• Factor ×5 growth in mass density over 4 < z < 6:
• Substantial mass density at z~5 suggesting much activity >300 Myr earlier (z > 7)
• Mass in place is integral of the past activity

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• Hard to reconcile implied past SF with that observed for luminous dropouts but implied SF nonethless may be sufficient to maintain reionization
• Perhaps early SF is in sub-L* galaxies or is obscured

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Stark & Ellis 2006, Stark et al 2007, 2009

Ouchi et al (2009)

• 1 deg² SXDS field with 608 photometric and 121 spectroscopic Lyα emitters
• Contrast with LBGs: no evolution 3<z<5.7!
• Tantalizing fading (0.^m3) seen in the LF of Ly α emitters over a small redshift interval 5.7< z< 6.6 (150 Myr)
• Does this mark the end of reionization corresponding to an increase in x_HI (e.g. x_HI ~0.6 at z~7)?

A Rapid Drop in Lyα Emitters from 5.7<z<6.6?

Searching for Ionized Bubbles

• z~7 z-dropouts appear strongly clustered.
• Lya emitting dropout sits at the center of overdense region of 4 UV brightest galaxies (~30Mpc )
• Speculation: The overdense region makes a well-established ionized bubble (>30Mpc) that allow the dropout to transmit Lya to observers in partially neutral IGM? → Spec. follow-up

UV bright dropouts

Lya emitting dropout

Size of HUDF/WFC3

Bubble??

Ouchi et al. (2009b, ApJ, 706, 1139)

Ouchi

Testing Reionization via Fraction of Ly α Emitters

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• Keck can probe redshift-dependent Lyα emitting fraction within continuum-selected Lyman break population
• Via z~7 WFC3/IR candidates can test for reduced Lyα fraction claimed by Subaru narrow band surveys

Stark et al, in prep

See also Clement

Hubble WFC3 High z Stampede

WFC3/IR: 850 - 1170nm

2.1 × 2.3 arcmin field of view

0.13 arcsec pixel^-1

10 times survey power of NIC3

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UDF 4.7 arcmin²

60 orbits in YJH

Reaches m_AB~29 (5σ)

Bouwens et al 0909.1803

Oesch et al 0909.1806

Bunker et al 0909.2255

McLure et al 0909.2437

Bouwens et al 0910.0001

Yan et al 0910.0077

Labbé et al 0910.0838

Bunker et al 0910.1098

Labbé et al 0911.1365

Finkelstein 0912.1338

z >7 candidates from WFC3 UDF campaign

McLure et al (2009)

15 z > 7 candidates

z’ Y J H

SED

χ²(z)

3 IR filters c.f. 2 leads to more secure photometric redshifts and reliable UV continuum slopes

But beware..uncertain redshifts still an issue..

z

Y

J

H

Results – I: Luminosity-dependent Evolution

Bouwens, McLure, Grazian

Results – II: z~7 Luminosity Function

Oesch et al, Bunker et al 2009

Ouchi 09 (Subaru)

WFC3 UDF

α = -1.86 ± 0.33 (Oesch)

α = -1.72 ± 0.65 (Ouchi)

NIC UDF

- 10-16 z-band dropouts to Y_AB~28.5 corresponding to 6.5<z<7.5 - Towards a reliable faint end slope: low star formers ~1 M_◉ yr^-1 dominant - Abundance decline of ~×2 since z=6

Did Star Forming Galaxies Reionize the Universe?

Stellar mass density at z~5-6 (and with greater uncertainty at z~7) implies past SF in low luminosity galaxies may be sufficient for reionization, especially if escape fraction of photons is >0.2

Stark et al 2007,2009; Labbé et al 2009ab

cosmic variance z~8

Will We Locate Pop III Stars?

Signature of metal-free Pop III stars may be realized with high quality spectroscopy (e.g. He II 1640 ~ 1-10% Ly α ) to z~14

NB: He II is only briefly visible in nebular phase (~ Myr)

z

Comoving SFR density

Pop III UV spectrum

Schaerer (2002)

stars

nebula

Bromm & Loeb (2006)

Bouwens, see also Bunker, Finkelstein (and early paper by Stanway)

Testing the High z Stellar IMF?

Integral of star formation history

Observed stellar masses

Is there any hope of testing the IMF in high z galaxies?

2003

2004

2005

2006

object: 234161

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host galaxy

m_r = 24.9 ± 0.07

g’ r’ i’ filters

SNe in z > 2 LBGs (CFHT SNLS)

image

subtraction

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SN is offset

from host

centroid by

2.8 ± 0.6 kpc

(physical)

object: 234161

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host galaxy

m_r = 24.9 ± 0.07

2005

g’ r’ i’ filters

SN event

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integrated magnitude

m_r = 26.3 ± 0.14

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SNe in z > 2 LBGs (CFHT SNLS)

g_max= 25.7

r_max= 25.2

i_,max= 25.1

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Keck LRIS spectrum of

LBG and supernova

Lyα at z=2.32

Confirmation of SNIIN (M > 40-60M_◉)

SN LBG

So far 6 SNIIn with z > 2

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Comparison of UV luminosity density of searched LBGs and number of SNIIn tests IMF in star-forming galaxies at z>2 !

Cooke, RSE et al

THE FUTURE

Herschel

James Webb ST

ALMA

SKA

LMT

TMT

Rawlings’ vision of complete inventory of stars, HI, H2 etc (no slide!)

Excitement of First Herschel Science Results

Oliver, Clements

Hermes & Atlas teams

Resolution comparison of BLAST, Herschel and JCMT at 500/450 microns

50 square arcmin simulation based on BLAST counts courtesy of Ed Chapin

Importance of Associated Facilities

Crucial roles for JCMT+SCUBA2, LMT + AzTEC, CCAT…

Dunlop, Arextaga, Hughes, Wilson

SPICA:�JAXA + ESA Cosmic Vision

62

3.5 m telescope

Cooled to < 6K

Instruments cover 5- 210 μm

• MIR spectro-photometer
• FIR imaging spectrometer.
• MIR Medium/High Resolution Spectrometer
• MIR coronagraph
• Focal Plane Camera dedicated to guidance
• FIR and sub-mm spectrometer – optional

Results - Spectra

HBLR z=0.0689

[NeV]

Obscuration

Extended source

strong PAH

AGN2 z=0.015167

Sy1 z=0.03301

Compact source

strong [NeV]

Spinoglio

The Multiplex Advantage

64

Looking closer at the SPIRE background sources

SPICA FIR FTS will take spectra of 7-10 sources/field

Images Rosenbloom, Oliver, Smith, Raab private communication

The Era of Extremely Large Telescopes

A new generation of 20-42m ELTs is being designed:

• Thirty Meter Telescope (www.tmt.org) - Caltech, UC, Canada, Japan +China - 30m f/1 primary via 492 × 1.4m segments - $80M design underway (2004-2009) - $300M raised so far
• Giant Magellan Telescope (www.gmto.org) - Carnegie, Harvard, AZ, TZ, Australia, S Korea - 21m f/0.7 primary via 7 × 8.2m segments - funds for $50M design study being raised
• European ELT (www.eso.org/projects/e-elt) - 42m f/1 primary with 900+ ×1.4m segments - 5 mirror design - 57M Euros design underway (2007-2010)

TMT

GMT

E-ELT

A partnership between: Caltech, U. California, Canada (Japan, China, Brazil?)

AO impacts JWST-TMT Synergy

TMT with AO will have better resolution than JWST (not a dream: Keck AO has better resolution than HST)

– together with large aperture significantly changes space-ground synergy

First sources & cosmic reionization:

• TMT is key to locating more abundant, fainter, smaller sources (AO gives ×10-100 gain over JWST depending on angular size).
• JWST probes to higher z in mid-IR

Lensed galaxies at z ~6

Unlensed sizes ~ 150pc or < 30mas!

Thanks to Conference Organizers..& ESF Staff