Post-Herschel FIR (20-500µm) science objectives

HIGH REDSHIFT OBJECTS.

Alain Omont (IAP)

A deep spectral window into the young Universe complementary to JWST and ALMA

Thanks to: F. Bertoldi, P. Cox, C. De Breuck, E. Falgarone, D. Flower, R. Neri, G. Pineau des ForêtsD. Leisawitz and other contributors to U. Maryland workshops & SAFIR, SPECS, SPICA & SIRCE projects

• Various redshift ranges in galaxy/AGN evolution (z ~ 0.5-20)

• Key astronomical issues

• Present����near-future high-z FIR-submm achievements

• Between JWST & ALMA: drawbacks & advantages

• High-z capabilities of a cryogenic, 8-10m telescope- Galaxy formation: H2 lines & PAH at z > 5 - Galaxy evolution, z ~ 0.5 –7 : spectral lines (+dust)- AGN environment & evolution

• High-z objectives for possible smaller telescopes

• Need for angular resolution���� prepare space interferometry

• Submm all-sky survey

Post-Herschel FIR (20-500µm) science objectives: High Redshift Objects

OUTLINE

z Dphot(Gpc)

1000

--------------------

20 230

12 130

--------------------

6 60

--------------------

2 16-------------------

0.5 3--------------------

0

~ 300 million

~ 3.5 billion

z ~ 7 – 20 ?- ReionizationPopIII stars +1st galaxies-Formation of 1st galaxiesPop. II stars- First AGN

z ~ 4 – 7 :Current frontier- Galaxies and QSOs detection- End of reionization

z ~ 1.5 -4: - Peak of star formationsubmm sources + LBGs- Peak of QSO activity- Proto-cluster formation

z ~ 0.5-1.5 : Final phase of active star formation- ISOCAM sources- Weak X-ray AGN- Cluster formation

X

X

ULIRG

LIRG

Spiral

PAHs

z= 5 1µm 10µm ||///////////////////100///////////////////| 1000

z= 10 1µm 10µm ||///////////////////100///////////////////| 1000

z= 2 1µm 10µm ||///////////////////100///////////////////| 1000

z= 0 |///////////////////////////////////////////|

High-z FIR Objects

X

Very steep SED« inverse K corr.»

High redshift objects

KEY ISSUESCosmology

Confirmation of standard ΛΛΛΛCDM model and parametersIdentification of dark matter and energyOther issues of fundamental physics: inflation, etc.

Formation and evolution of galaxies and structuresFormation of first stars and galaxies; reionizationMerging historyHistory of star formationFormation of clusters and proto-clusters of galaxies

Formation and evolution of massive black-holesFormation and growthPhysics of their environmentRelation with their host galaxy; parallel evolutionMerging of massive black-holes

Main present���� near-future10-1000µµµµm high-z achievements• Extragalactic background and resolution into sources, ���� Energy generation history COBE, ISO, SCUBA����SIRTF, Astro-F, Herschel.

• Star formation historyup to z ~ 20-30ISO, SCUBA����SIRTF, Astro-F, Herschel, ALMA, JWST

• ULIRGs full census and propertiesSCUBA����Herschel, ALMA, Astro-F, WISE

• Detection of galaxies at reionizationepoch���� z ~ 20ALMA, JWST

• Details of galaxy astrophysics/evolutionup to z ~ 3-5ALMA, JWST

• AGN/star-formation connection

• SZ/Ostriker-Vishniak effect from reionizationALMA, etc.

SCUBA (+MAMBO) submm counts

SCUBA(-radio) redshift distributionChapman, Blain, Ivison, Smail 2003

Star-formation rate

SCUBA(-MAMBO) census of high-z ULIRGs

• Take advantage of steep submmspectrum• Account for the whole submm background• zat Keck for radio ones(~50%) (weak AGN ?)���� History of star formationup to z~3-4•Small but uncertain number at z>4�CO detected at IRAM-PdB in 6-8

(Neri et al 2003)

Main present���� near-future 10-1000µµµµm high-z achievements

AGN/star formation connection

• ISO/SWS: disentangling AGN & starburst lines in ULIRGs

• ISOCAM: strong correlation between 15µm & X-Ray (z~0.5-1)

•MAMBO/ IRAM-30m & SCUBA:Dust detection in ~70 high-z QSOs (����z=6.4) and ~15 radiogalaxies

LFIR ~ 1013Lo, starburst or AGN heating

• IRAM PdB (+OVRO, Nobeyama):CO detection in 15 z>2 QSOs or radiogalaxies ���� z = 6.4 ���� starburst����mass of H2 gas up to 1010 Mo, T up to 100K, n up to >104cm-3

• AGN/starburst connection in ~50% of SCUBA galaxies

• Many extensions of ISO work with SIRTF, Astro-F, WISE, Herschel

• Detailed extension of IRAM work with ALMA up to z~15

CO detection at z = 6.42 at VLA & IRAM-Plateau de Bure

CO detection at z = 6.42Bertoldi et al. 2003a, Walter et al 2003, Bertoldi et al. 2003b

Between JWST & ALMA: drawbacks & advantages• JWST: extraordinary sensitivity, peak of stellar emission

high angular and spectral resolution• ALMA: enormous advantage of steep submm dust & CO emission

high velocity (heterodyne) & spatial (interferometry) resolution

• 20-500µm:- Large fraction of (starburst) galaxies energy emitted or redshifted- Crucial for dust enshroudedstar formation and AGN- Main ISM atomic lines, H2, redshifted PAH bands- Very sensitive detectors, weak zodiacal and Galactic background- No galaxy confusion limits for spectroscopy

• But:- Poor resolution with single apertures, very difficult interferometry- ���� Strong galaxy confusion- Difficult heterodyne- No « inverse K correction » for dust and line emission

X

X

ULIRG

LIRG

Spiral

PAHs

z= 5 1µm 10µm ||///////////////////100///////////////////| 1000

z= 10 1µm 10µm ||///////////////////100///////////////////| 1000

z= 2 1µm 10µm ||///////////////////100///////////////////| 1000

z= 0 |///////////////////////////////////////////|

High-z FIR Objects

X

Very steep SED« inverse K corr.»

50 80 100 120 150 200 µm

NII OI CIIOIII OI OIII

Between JWST & ALMA: drawbacks & advantages• JWST: extraordinary sensitivity, peak of stellar emission

high angular and spectral resolution• ALMA: enormous advantage of steep submm dust & CO emission

high velocity (heterodyne) & spatial (interferometry) resolution

• 20-500µm:- Large fraction of (starburst) galaxies energy emitted or redshifted- Crucial for dust enshroudedstar formation and AGN- Main ISM atomic lines, H2, redshifted PAH bands- Very sensitive detectors, weak zodiacal and Galactic background- No galaxy confusion limits for spectroscopy

• But:- Poor resolution with single apertures, very difficult interferometry- ���� Strong galaxy confusion- Difficult heterodyne- No « inverse K correction » for dust and line emission

20µm - 500µm

• Studies at z ~ 5-10 - (end of) reionization epoch – are possible, including spectroscopy

• Detailed studies of galaxies and AGN at z ~ 0.5-4 are easy

WITH A LARGE (8-10m) SINGLE APERTURE TELESCOPEe.g. SAFIR (���� H. Yorke)

- Galaxy formation: (pristine) H2 lines & PAH bands at z > 5- Galaxy evolution, z ~ 0.5 –7 : MIS/star-formation lines- AGN environment & evolution

SAFIR capabilities in comparison

SAFIR will offer orders of magnitude improvement in

• spectroscopic sensitivity• point source detectivity

no confusion limits for spectroscopy!

~ 104

~ 102

• Also large increase in the numberof pixels

R=1000

Arp 220 at z=10M 82 at z=10M 51 at z=5

SPICA

High-z point sources, continuum sensitivity

Detection of large starburst galaxies at z ~10L* galaxies at z ~ 5

Confusion limited at λλλλ>100µm

At least similar sensitivityfor starburst PAH features �z determination

Gravitational lens magnification- a few % of high z sources- factor ~ 2-10 (����10-15)�higher z or fainter objects

�����

* z ~ 5-10 range well studied* lens exploration of higher z*structures well traced at smaller z

8-10m

Fine structure lines: CII, OI, OIII, NII, SiII, FeII, ArIII, etc.Enormous sensitivity gain vs SIRTF/Herschel

Often extinction free, but not in Arp 220 ���� some lines in absorption

• Cooling of the ISM; T and n diagnostic; ionization

• Element abundances���� chemical evolution of galaxies

• Width ���� rotation, dynamical mass(but no heterodyne and spatially unresolved)

• Redshift determination���� tracing structures (high source density, large field of view)

• ���� Combination with ALMA: submm molecular lines: CO, etc.

• ���� IR molecular lines: H2, HD, H2O, OH, etc.���� chemistry, isotopes

Dust spectroscopy�dust composition at all z in various environments

8-10m

50 80 100 120 150 200 µm

NII OI CIIOIII OI OIII

.

Rotational H2 lines

Need warm molecular gas : T > 100 Kbecause first line, J2����0 (28µm) Tup~500 K

Detected in local galaxies by ISO/SWS,surprisinly strong and extended,

e.g. in non-starburst NGC 891� MH2 ~ 2 109 Mo, T ~ 170 K Valentijn & van der Werf 1999

� Detectable in massive galaxies (MH2 > 109 Mo) up to z = 10 !(J 1148 at z=6.4 has MH2 ~ 2 1010 Mo)

� Detailed view of warm molecular gas at all redshifts up to z ~ 5 (PDRs, shocks, turbulence ?)

[H2EX for local H2 up to z~1]

---------------------------- J = 4 para H2

12 µm

--------------------------- J = 3 ortho H2

17 µm

--------------------------- J = 228 µm

--------------------------- J = 1---------------------------- J = 0

8-10m

Possibilty of detecting pristine H2 in galaxy formation

Detection of H2 at z~10 requires about 109 Mo of warm H2

H2 cooling is crucial for the formation of the first stars and galaxies from pristine gas without metals

However, typical (dust-free) « pristine » H2/H ~ 10-3, and masses of first condensations (Pop. III stars ?) are too small for H2 lines to be detectable

Larger condensations can later collapse at T~104K; however, their subsequent physics and that of H2 are terribly complex and uncertain :photodissociation feedback of H2, but maybe additional H2 formation ??

8-10m

• Detection of pristine H2 is thus possible but uncertain

• It could be helped by (strong) lensing

• Anyway, large (starburst) galaxies with metals already abundant at z~5(Bremer et al 2003) ; maybe reionization agents; H2 detectable���� z=10 ( ����15 with lensing)

High-z AGN

Mid-IR (rest-frame), high ionization lines provide powerfulextinction-free diagnostics of dust-enshrouded AGN :

[MgV] 13.5 , [OIV] 26 , [ArV] 13, and [NeV] 14 and 24µm

• Very strong, detectable at very high z

• Very good discrimination AGN/starburst combiningwith HII lines: soft FeII,III, NeII, SIII, hard SiIV, NeIII, OIII

• Broad lines ���� dynamics of nuclear toroids ���� mass of highly buried black-holes

���� understanding correlation mass-BH/mass-bulge

�accretion history of universe (with X-ray missions)

+ Dust composition around high-z AGN

HII

AGN

8-10m

Arp 220 at z=10

SPICA

Interest of smaller missionsat high redshifte.g. cold 3.5m at L2: SPICA(���� T. Nakagawa)

• Severely limited by confusion for point source continuum

• But still very impressive spectral capabilityfor PAH, fine structure & H2 lines, dust composition, including peak of starburst/AGN activity at z ~ 2• However cannot tackle galaxy-formation/reionization epoch at z > 5

H2EX (1.3m) is limited to the local universe ���� F. Boulanger

SPICA

Submillimeter whole sky survey ���� V. Gromove.g. SIRCE 2m Benford et al.

• Severely limited by confusion (���� more ambitious 3.5m Lamarre)���� a few 107 sources at 500 µm���� >~ 10 mJy���� mostly typical SCUBA sources at z 7 :- strongly lensed- and/or AGN extremely luminous atλλλλ ~ 60 µm

• SZ sources

• Main key special interests- First massive (dusty) condensations in the Universe- Very rare extremely lensed ULIRGs, especially at z>7,

for ALMA, JWST, etc.- Maybe a few (lensed) strong radiosources at z~10 for tracing

HI (21cm) at reionization ?

Need for angular resolution in the far infrared

• Lack of angular resolution in the far-IR/submm is one of the Main drawbacks of single apertures compared to ALMA, JWST

At high z, 1 arcsec = 8-4 kpc at z = 2-10���� no access to galactic structure� no discrimination of AGN environment� source confusion in submm� no resolution of lensed images

• Need for sensitive space interferometry, to be combined with high spectral resolution, e.g. SPECS (���� Leisawitz)

- highly demanding, long-term goal- need to begin to design, build and test the technology

ConclusionsSensitive far-infrared capabilities are mandatory to understandthe high redshift Universe in complement of JWST and ALMA, for:

- Dust-enshrouded star formation- Properties of the ISM, energy balance, chemical evolution,etc- AGN/host-galaxy connection & dust-enshrouded AGN- Dust properties- Galaxy formation and the role of pristine H2

• A large (8-10m) cold telescope has an enormous gain of capabilities, and is required for the most demanding objectives, especially at z >~4

• A smaller (3-4m) aperture may achieve important goals

• Space FIR interferometry will be required to achieve high angular resolutioncombined with high spectral resolution

• A submm sky survey will trace star-formation peaks in whole Universe and increase ALMA/JWST discovery power by revealing unique (lensed) dusty sources

One may expect seredenpitous discoveries from the enormous gain of capabilities of such future missions