Thomas R. GreveMax-Planck Institute for AstronomyGalaxy Formation and Evolution from the Epoch of Reionization to z=4Purple Mountain Observatory, Nanjing, April 3rd 2009

1) Cosmic history: the Universe beyond z > 4- Identifying outstanding problems in galaxy formation and evolution and key science drivers for the next decade

2) How do we find galaxies at z > 4?- Dust obscured star formation at z > 4- All-sky optical/near-IR surveys: hunting for z > 4 QSOs - Pristine galaxies at z > 4: Lyman- Emitters

3) Understanding the interstellar medium in z > 4 galaxies?- How interstellar medium studies can help solve the key problems in galaxy formation and evolution

4) Summary

Outline of this talk

Cosmic history: the Universe beyond z > 4

Identifying outstanding problems in galaxy formation and evolution and key science drivers for the next decade

Cosmic History

The new cosmic frontier: the epoch of reionizationKey questions to be addressed in the coming decade:

-When did the EoR start?

-How and when did the first galaxies form?

-How and when did the first supermassive black holes form?

-What was the inter-relationship between supermassive black hole and host galaxy growth at these early epochs?

This requires large, robust samples of z > 4 galaxies!

Dust obscured star formation at z > 42) How do we best observe the first galaxies at z > 4?

LIR = 1x1013LThe dust-obscured UniverseUVHughes et al. (1998)HDF-N850mSCUBAJCMT, Hawaii

~1 sq. degree of sky has been surveyed at submm wavelengths to date resulting in the detection of more than ~400 bright SMGs (>3mJy)

~20-30% of the (sub)mm background has been resolved by blank-field surveys. ~80% by galaxy cluster surveys but poor number statisticsThe submm Universe

Submillimetre/Millimetre SurveysHDF-NSubmm surveys suffer from poor resolution (FWHM=11-15)

A significant population of z > 4 SMGs?

A significant population of z > 4 SMGs?Discovery: a z=4.76 submm-selected source not associated with a QSOSMMJ033229.5 (z=4.76 from optical spectrum) Coppin et al. (2009)870m APEX/LABOCA Survey

A significant population of z > 4 SMGs?

The next submillimetre revolutionSCUBA-2 (first light 2009)

ALMA (first light 2012)

SCUBA-2 will deliver thousands of submm-selected sources

Sub-arcsecond submm/mm interferometry with ALMA:- immediate identification (no need for radio identification)

A census of the z > 4 submm population

Dust obscured star formation at z > 4 All-sky optical/near-IR surveys: hunting for z > 4 QSOs Pristine galaxies at z > 4: Lyman- Emitters

2) How do we best observe the first galaxies at z > 4?

All-sky optical/near-IR surveys: hunting for z>4 QSOsAll-sky surveys such as the SLOAN have found numerous, extremely luminous z > 4 QSOs by means of drop-out techniques in the opticalThey represent massive, extremely rare, overdensities in the primordial density distribution.

The extreme luminosities of z > 4 QSOs make them ideal laboratories to study galaxy formation and black hole growth at the high-mass-endAll-sky optical/near-IR surveys: hunting for z>4 QSOs

Extreme galaxy in place 4 QSOs make them ideal laboratories to study galaxy formation and black hole growth at the high-mass-endLFIR 1013LMgas 7 x 1010MMdust 109M

All-sky optical/near-IR surveys: hunting for z>4 QSOs

Future large samples of distant QSOsFull UKIDSS Large Area Survey (4000 deg2, Y z > 5.8 QSOs: 17 Full Pan-STARRS Survey (10,000 deg2, Y z > 5.8 QSOs: 73 These samples of QSOs will be prime targets for multi-line molecular/atomic follow-up observations!

Dust obscured star formation at z > 4All-sky optical/near-IR surveys: hunting for z > 4 QSOs Pristine galaxies at z > 4: Lyman- Emitters

1) How do we best observe the first galaxies at z > 4?

Pristine galaxies at z > 4: Lyman- EmittersKodaira et al. (2003)z=6.541z=6.578In the absence of dust and strong optical continuum, the easiest way to find the first galaxies is via the Ly recombination line: the strongest emission line produced by the hydrogen atom (Partridge & Peebles 1967)

Gawiser et al. (2007)

Pristine galaxies at z > 4: Lyman- EmittersLyman- Emitters (LAEs) are likely to be pure starbursts and representing the first building-blocks of galaxiesThe large number of z > 6 LAEs (30 per 0.25 sq. deg) implies that they could play a dominant role in reionizing the Universe

There are currently several hundreds known LAEs at z > 4

JWST+ELT will be able to detect the smallest and most distant galaxies (z > 7), increasing the number of LAEs by order of magnitude

Future samples of distant Lyman- emittersExtremely Large Telescope30m optical/near-IR ground-based telescope

Dust obscured star formation at z > 4All-sky optical/near-IR surveys: hunting for z > 4 QSOsPristine galaxies at z > 4: Lyman- Emitters

1) How do we best observe the first galaxies at z > 4?

What is the most effective way of studying these first galaxies in order to maximize constraints on formation and evolution models?

The gravitational hierarchical build-up of dark matter structures provides the framework for galaxy formation and evolution

Springel et al. (2006), NatureThe interstellar medium (gas and dust) is a key ingredient in galaxy formation and evolution as it provides the fuel for star formation and supermassive black hole accretion

The role of gas in galaxy formation and evolutionDark matterDark matterDark matterGalaxyGalaxyGalaxyso understanding the physical properties of the interstellar medium (ISM) in distant galaxies is fundamental to our picture of galaxy formation and evolution

Observing the interstellar mediumOther important molecular gas tracers: HCN and HCO+Atomic fine-structure lines: [CI] and [CII] ( = 490-1900GHz) Molecular hydrogen (H2) is by far the main component of the ISM but its lack of a permanent dipole moment makes it virtually impossible to observe directly Instead the rotational lines of CO are mainly used to study the ISM J=1-0 ( = 115GHz)J=2-1 ( = 230GHz) . . .The CO J=1-0 line from a local galaxy falls within the 3mm atmospheric window,

as does the (redshifted) CO J=5-4 line from a galaxy at z=4 (obs = 575GHz/(1+z) = 115GHz) DensityTemperature 1-0 Atmospheric transmission vs. frequency 2-1 3-2 CO 5-4

Observational status

This excitation-bias prevents a meaningful comparison between the molecular gas properties of local and high-z galaxies

Greve (2009)

The next five years will see a quantum leap in our ability to study the ISM in galaxies across the Cosmos - one that will take us from an epoch of merely detecting molecular lines at high-z to multi-line surveys capable of fully characterizing the ISM

A new golden era in ISM astronomy

Requires:An exhaustive inventory of the microscopic properties (e.g. chemistry, density, thermal balance) of the ISM in z > 4 galaxies, and their effect on macroscopic properties (e.g. star formation, luminosity, morphology)

Method:- Sampling of the spectral line distributions of CO, HCN and HCO+, [CII] 158m and [CI] 369m

- Spatially and kinematically resolved dust and molecular line observations

- For large samples of z > 4 objects (QSOs, SMGs, and LAEs)

A full understanding of galaxy formation and evolution at z > 4A new golden era in ISM astronomyKey Questions:-When did the EoR start?

-How and when did the first galaxies form?

-How and when did the first supermassive black holes form?

-What was the inter-relationship between supermassive black hole and host galaxy growth at these early epochs?

High-z ISM studies at sub-kpc scalesHigh-resolution observations of the dust and molecular gas provide a direct image of the formation morphology, and can distinguish between several scenarios

A major merger between two gas-rich components (wet merger)

Many minor bursts distributed within an extended potential and interspersed with periods of no star formation

A single monolithic collapse

In addition, one obtains accuratedynamical masses, merger fractions etc.

Imaging galaxy formation

Black hole and galaxy host growth at z > 4Mbulge=0.002MBH scatter < 0.30dex

High-z ISM studies at sub-kpc scalesAn unusually tight relation between the mass of the supermassive black hole and that of its host spheriod has been established in the local Universe.

This relation connects a phenomenon ocuring on spatial scales of 10-5pc (black hole accretion) to the spheriod which is 8 orders of magnitude larger (103pc )

This suggest a deep, co-evolutionary link between the supermassive black hole and the galaxy spheriod.

What is the underlying physics?How does the relation evolve with redshift?

Local relation

Did the black holes start to grow first?

High-resolution CO studies can uniquely probe the MBH-Mbulge relation at high-zLocal relation

QSOs

High-z ISM studies at sub-kpc scalesBlack hole and galaxy host growth at z > 4

Local relation

Or did the bulges grow first?

High-resolution CO studies can uniquely probe the MBH-Mbulge relation at high-zQSOs

SMGs

High-z ISM studies at sub-kpc scalesBlack hole and galaxy host growth at z > 4

Requires:An exhaustive inventory of the microscopic properties (e.g. chemistry, density, thermal balance) of the ISM in z > 4 galaxies, and their effect on macroscopic properties (e.g. star formation, luminosity, morphology)

Method:- Sampling of the spectral line distributions of CO, HCN and HCO+, [CII] 158m and [CI] 369m

- Spatially and kinematically resolved dust and molecular line observations

- For large samples of z > 4 objects (QSOs, SMGs, and LAEs)

A full understanding of galaxy formation and evolution at z > 4A new golden era in ISM astronomyKey Questions:-When did the EoR start?

-How and when did the first galaxies form?

-How and when did the first supermassive black holes form?

-What was the inter-relationship between supermassive black hole and host galaxy growth at these early epochs?

The ISM conditions at z > 4: the density structure of the gasThe dense gas fraction of the ISM in a galaxy may govern its star formation efficiency and hence its evolutionary path. Determining the density structure of the ISM requires a very complete sampling of the CO rotational ladderIs the ISM in QSOs more excited than in submm-selected galaxies?

The ISM conditions at z > 4: the density structure of the gasWeiss et al. (2006)Determining the density structure of the ISM requires a very complete sampling of the CO rotational ladder. As well as of dense gas tracers such as HCN and HCO+

The ISM conditions at z > 4: gas coolingThe [CII] 158m line is the main cooling line in our Galaxy and in typical local starburst (L[CII]/LIR 5x10-3)However, [CII] cools 10x less efficiently in the most IR-luminous galaxies (at low- and high-z)

The ISM conditions at z > 4: gas coolingThe [CII] 158m line is the main cooling line in our Galaxy and in typical local starburst (L[CII]/LIR 5x10-3)However, [CII] cools 10x less efficiently in the most IR-luminous galaxies (at low- and high-z)In metal-poor systems, however, we can have L[CII]/LIR 0.5-1x10-2

An z=7 LAE with LIR 2x1011L (SFR=30M/yr) will be detectable with ALMA! SDSSJ1148+5152 (z=6.42)

Detecting the first objects at z > 7 with ALMAThe [CII] 158m line may be the line of choice for z > 7 objects with ALMA[CII] is 5x brighter than CO(6-5)

Summary

Future surveys with PanSTARRS/UKIDSS, SCUBA-2, and JWST/ELT will drastically increase sample sizes of z > 4 galaxies

The next 5-10 years will see the advent of a number of new, ground-breaking cm/submm/far-IR facilities (e.g. ALMA, EVLA) allowing us to study such samples effectively

For the first time it will be possible to do a detailed characterization of the ISM in primeval galaxies during the epoch of reionization

This will revolutionize our understanding of galaxy formation and evolution at all cosmic epochs

Add STFC February 2009*Add STFC February 2009*Add STFC February 2009*Gas is greenWhat is red in Capak? *Gas is greenWhat is red in Capak? *Add STFC February 2009*Submillimeter galaxiesThe first blank-field submillimeter map was taken with SCUBA of the HDF-N.A handful of submm-sources were detected - and they had no obvious optical/nir counterpart, thus suggesting that these were high-z, dust-obscured starbursts.The surface density of significant sources in the field was so large that the implications were that SMGs constituted a significant population of dust-enshrouded starburst galaxies.

Since then the (sub)mm surveys have increased in size - here are an example of that in the HDF-N/GOODS-N, which has now also been osbserved with MAMBO at 1200um. The largest areas surveys today are of the order 1sq. Degree - and several hundreds of SMGs have been detected.

This has resulted in about 25% of the background at 850um has been resolved, maybe as much as 80% when using clusters as grav. Lenses.At 1200um about 15% has been resolved.

We now also know the redshift distribution of the brightest SMGs with radio counterparts, thanks to Keck/LRIS.Blue curve is a model prediction of the SMGs with S850>5mJy..Green dashed is a model prediction of N(z) for S1.4>30uJy. Both models are based on the Blain et al. 2002 models.Horizontal shades: the fraction of SMGs we are missing due to our radio flux limit.Vertical shades: The redshift desert = no strong line features enters the observable range of LRIS.

Their abundance are comparable to that of local massive spheroids, suggesting an evolutionary link between the two.

Remember to mention cluster lens surveys!*Gas is greenWhat is red in Capak? *Add STFC February 2009*Gas is greenWhat is red in Capak? *The most distant quasars at redshifts z > 6 are observed at a time when the universe was less than a billion years old (at the end of the so-called Epoch of Reionization). One of the key aspects in studying these extreme systems is the question how they were able to assemble so quickly after the big bang and what the nature of their extreme far-infrared luminosities is. Radio observations are critical to constrain the properties of the host galaxies and to estimate the total amount of molecular gas. Spectroscopy of molecular gas is currently the only means by which the dynamical masses of the host galaxies in these early systems can be constrained, and thus provide the earliest data points for the evolution of the black hole bulge mass relation with cosmic time (see next*The most distant quasars at redshifts z > 6 are observed at a time when the universe was less than a billion years old (at the end of the so-called Epoch of Reionization). One of the key aspects in studying these extreme systems is the question how they were able to assemble so quickly after the big bang and what the nature of their extreme far-infrared luminosities is. Radio observations are critical to constrain the properties of the host galaxies and to estimate the total amount of molecular gas. Spectroscopy of molecular gas is currently the only means by which the dynamical masses of the host galaxies in these early systems can be constrained, and thus provide the earliest data points for the evolution of the black hole bulge mass relation with cosmic time (see next*Add STFC February 2009*Gas is greenWhat is red in Capak? ***Add STFC February 2009*Gas is greenWhat is red in Capak? *

Not easily observable H2*Redo-plot, showing the epoch of reionization!***Gas is greenWhat is red in Capak? *n recent years a very tight relation between the mass of the central black hole and the stellar density concentration in galaxies (the "bulge") has been established for local galaxies. Does this imply that black holes and galactic bulges evolve strictly coeval or does it merely indicate that big galaxies eventually grow massive black holes ?We try to establish the evolution of the M(black hole) M(bulge) relation over the last 10 billion years. To this end we have to supplement estimates of the black hole mass in quasars (from broad emission lines) with dynamical masses of their host galaxies. The latter will be determined from high spatial resolution Halpha rotation curves to be obtained with adaptive optics observations using SINFONI and PARSEC at the VLT.

In this technique, time delays between brightness variations in the continuum and in the broad emission lines are interpreted as the light travel time between the BH and the line-emitting region farther out. This provides an estimate of the radius r of the broad-line region. We also have a velocity V from the FWHM of the emission lines. Together, these measure a mass , 2 M V r/G bh where G is the gravitational constant. An important advantage is that the BLR is 10 2 times closer to the BH than the stars and gas that are used in HST spectroscopy.

****Very few objects where the full CO ladderOnly one at the moment

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