Conference Summary

Richard Ellis (Caltech)

ITALIA

DEUTSCHLAND

SCHWEIZ

ÖSTERREICH

View from Top Mountain Star

Happiness is an espresso and Jägermeister at the Top Mountain Star…and a redshift 10 galaxy.

Disclaimer

67 talks × 30 slides = 2010 slides

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AND 35 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 - I

Support for standard model ΛCDM strengthened (White)

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- precision cosmology from CMB

- Cold DM particle vindicated by Lyα forest simulations

- Local Group dwarf discrepancies must relate to baryonic feedback

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- Measurement ≠ understanding (DM/DE remain a mystery)

Viel et al (2013)

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

Theoretical Progress - II

Numerical simulations incorporating hydrodynamics have as much or more predictive power as semi-analytic models (Schaye, Sparre, Henriques, Popping) matching:

- stellar mass functions; star formation histories; color bimodality

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Theoretical Challenges - I

But aren’t there degeneracies in matching integrated properties of galaxies?

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Empirical methods for quantifying mass and environmental-dependent processes offer a refreshing complement to detailed simulations (Lilly)

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The challenge is to marry the two approaches to agree the details of the physical processes involved

Peng et al 2010, 2011

Theoretical Challenges - II

Understanding the gas-phase metal distribution (that in CGM > galaxies)

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Tumlinson et al 2011

COS spectra of 42 galaxies in the vicinity of background QSOs reveals ubiquitous halos of OVI at impact parameters up to 150 kpc

Theoretical Progress

First steps in predicting resolved properties of galaxies with moving mesh AREPO-based simulations (tested against GADGET-based SPH)

Vogelsberger et al 2012, 2013, Torrey et al 2014

Stars

Gas

Metals

Feedback

No feedback

White, Ceverino

Resolved Metal Gradients in Lensed z~2-3 LBGs

HST

The strong magnification for two images of z=2.00 LBG recovers the [O/H] gradient with ~200 pc resolution in the source plane

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Outflow properties follow directly from echellette spectroscopy

Jones et al (2010)

AO resolution sans lensing

Abundance Gradients for Larger Samples Coming..

15 systems from catalog of >50 spectroscopically-confirmed examples

Stark et al 2013

Evolution of Cosmic Gas Density

Next observational frontier after SFR and stellar mass histories:

provides SF efficiency (Narayanan, Lagos, Elbaz, Munoz, Hayward, Hodge, Biggs)

Zafar et al 2013

Saintonge et al 2013

Great progress in surveys and resolved data of targeted examples

Big challenges in utilizing observations and interpreting results

conversion from CO to H₂, CO excitation (high J to low J)…

HI

H₂

The densities of SFR and H2

Lagos et al. (2014)

Difference comes from the contribution from starbursts: they contribute more to the SFR than to H₂ (SF more efficient)

Contrasting Star Formation and H₂

The densities of SFR and HI

Lagos et al. (2014)

(1) The evolution of total neutral gas: �outflow vs. inflow

(2) The size evolution of galaxies: �gas density

Contrasting Star Formation and HI

No Need For Bimodal X_CO?

Narayanan

Modeling gas kinematics/thermal structure, gas-phase metallicity suggests nature is continuous, not bimodal

Continuous X_CO improves interpretation of main sequence

First CO Deep Fields

Walter et al 2014, Decarli et al 2014, Chapman..

Narayanan

Consider an input SFH and its implied H₂ density as TRUTH, limitations of current methodologies could lead to BIASED MEASURE

Resolving the SMGs

Hayward, Geach, Hodge, Walth, Zavala

SMA (Wang et al 2011) and later ALMA (Karim et al 2013) resolve individual sub-mm galaxies revealing multiple components, often at different redshift.

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Typically <65% of the original integrated flux lies in the primary component

ALMA (Karim et al 2013)

SMA (Wang et al 2011)

Correlating FIR emission with LBGs

Geach

Confusion on CII] Detections at High Redshift

The ALMA Story (so far..)

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• ALMA afficionados proclaim CII] is the savior in spectroscopic verification of high redshift SF galaxies
• Ouchi et al (2013) find no CII] in the most intense LAE at z~6.6 (SFR ~100 M_◉ yr^-1)
• Manucci et al report CII] detection of CII] at z~7.1 in LBG with SFR<10 M_◉ yr^-1

Ouchi, Williams, Munoz

The Most Exciting Development?

Watson

A truly remarkable achievement:

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• A spectroscopic redshift at z~7.5 without detecting Lyα!
• Detailed information on a low mass (log M*~9.2) galaxy representative of those contributing to reionization
• ALMA band 6 detection: dust in a system with typical UV properties!

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Cosmic Dawn and Reionization

time

baby galaxies

dark hydrogen clouds

ionized gas bubbles

fully ionized gas

Courtesy: Avi Loeb

Huge progress in observations (HST, ground-based spectroscopy) and simulations of first stars and reionization

Bromm, Robertson, McLure, Stark, Ciardi, Ouchi, Dayal, Wilkins

Bromm

Extremely massive (>100 M_◉) first stars unlikely

How Did Massive Black Holes in z>6 QSOs Form?

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Bromm, Haehnelt

Leo IV abundances c.f. Pop III supernova models

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Pop III Phase May Be Very Short-lived

Leo IV star

10 M_◉, normal energy

30 M_◉, high energy

Simon et al (2011)

Bromm

Progress in Reionization Studies Using 21cm Surveys

Matching simulations with LOFAR, can expect good progress via power spectrum analyses in 7<z<11 shortly

Ciardi, Meisinger, Scobbachi

Lyα visibility decline

• MOSFIRE provides an impressive improvement in z>7 spectroscopy!

Treu et al (2013) – Keck MOSFIRE + BoRG z~8

Finkelstein et al (2013) – Keck MOSFIRE + CANDELS z > 7

Schenker et al (2014) – Keck MOSFIRE + UDF, CLASH 7<z<8.2

Pentericci et al (2014 in prep) – VLT FORS 6<z<7.3

Schenker et al 2014

Konno et al 2014

Stark, Ouchi

~1.5 deg

FoV of HSC

FoV of Suprime

1.7m

Clustering of Lyman α Emitters

The spatial distribution of Lyα emitters over key redshift ranges 5.7, 6.6 and 7.0 contains information on the emerging distribution of ionized bubbles; expect boosting in bias at higher z.

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Can explore with Subaru’s unique imager HSC and massive-multiplexed spectrograph PFS

Subaru 8m

HSC corrector

Ouchi et al (2010)

High Redshift Measurements without Lyα?

Spectra of lensed 10^6-9 M_⦿ z~2-3 galaxies with properties similar to those at z~7

CIII] 1909 Å is stronger in such systems (EW~10-30 Å) reflecting larger T_e and harder ionizing spectrum expected at low (10% solar) metallicities.

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Stark et al (2014a, b)

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First Confirmation of z>6 Sources using CIII]

Stark

Hubble WFC3 High z Stampede (2009)

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

Progress With Hubble Space Telescope

Ferguson, Robertson, Bouwens, McLure

Ultra Deep Field 2012 (>80 galaxies z>6.5)

Wider Area CANDELS survey

z~7 Luminosity Function (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

z~7 Luminosity Function (2014)

Bowler

Tail of luminous galaxies detected only in ground-based panoramic surceys (UltraVISTA, UDS) suggests demise of AGN feedback at early times?

Star Formation History

1Byr 800Myr 400Myr 350Myr

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UDF12/CANDELS, in agreement with CLASH, smooth decline in SF

history to z~10

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Bouwens+(2011), Oesch+(2013) originally claimed a `cliff’ at z~8 but this now seems unlikely

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Continuity has important implications for z>10 studies with JWST and models of reionization

http://udf12.arizona.edu

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Oesch et al 2013

β - wars are over?!

Gonzalez, Smit, Stark, Maseda

Both spectroscopic and ingenious photometric tests confirm increasing nebular emission pollutes broad-band photometry at high z.

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Although we can correct this contamination, why are these lines so strong?

Specific Star Formation Rate: Nebular Emission

Bursty Star Formation

Stark

It is not necessary for the nebular contribution to be consistent with the stellar fit to the continuum SED

The Full Monty: Galaxies Ended the Dark Ages

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HST star formation

Ionized fraction

Spitzer old stars

WMAP τ

The UDF2012 star formation rate density (N(z) and faint end LF slope) integrates to match the stellar mass density and given ξ_ion ( β) matches the CMB optical depth τ

provided

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• LF extrapolated to M_UV~-13
• f_esc~0.2
• SFR extends beyond z~10

Robertson et al (2013)

Unique Role of GRBs

Tanvir

GRBs continue to play an independent role in reionization studies:

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SF history, HI optical depth etc

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Role of Frontier Fields - I

z=5.6

z=6.8

Ellis et al (2001), Kneib et al (2005)

Multiply-imaged sources close to the `critical line’ of maximum magnification offer a number of unique advantages:

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• Geometrically constrained high magnifications (e.g. ×33 and ×25 here)
• Consequent good photometry and spectroscopic possibilities
• Resolved morphologies

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But they are RARE because the relevant survey volume is tiny!

Abell 2218

Kawamata

Role of Frontier Fields - II

A singly-imaged source is located in the vicinity of a cluster but away from the critical line. It offers no geometric information. The magnification is less. Such sources are much more common but offer only a modest boosting in flux

Bradley et al arXiv 1308.1692

Abell 1689

z=7.35

Area vs magnification for ~250 lensed sources in 18 CLASH clusters

Accuracy of Magnification Maps (A2744)

Robertson

Cosmic Variance

RMS/mean

For the first Frontier Field cluster, independently submitted magnification maps and the limited survey volume in the source plane allow us to estimate the uncertainties in surveys of faint high redshift galaxies

THE FUTURE (Steve Rawlings 1961-2012)

James Webb ST

ALMA

SKA

LMT

TMT

SVOM

The Era of Extremely Large Telescopes (ca. 2009!)

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

• Thirty Meter Telescope (www.tmt.org) - Caltech, UC, Canada, Japan +China + India - 30m f/1 primary via 492 × 1.4m segments - $80M design underway (2004-2009) - $300M raised so far

Almost there..ground-breaking Oct 2014

• 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

Substantial progress; construction underway

• 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)

Ground preparation underway, waiting for Brazil

TMT

GMT

E-ELT

Thanks to Conference Organizers!!