Molecules in high redshift galaxies as probes of star formation and galaxy evolution Alain Omont

1. Molecules in high redshift galaxies as probes of star formation and galaxy evolution Alain Omont (IAP, CNRS and Université Paris 6)

2. OUTLINE Molecules in high redshift galaxies as probes of star formation and galaxy evolution • General Features • - Molecules in the ISM of galaxies • - Molecules at high redshift • Millimeter emission of molecules at very high redshift (PdBI) • - CO and the structure of starbursts in SMGs • - Mm follow up of the Spitzer heritage • - CO in high z QSOs and the MBH/Mspheroid relation • PAHs as tracers of starbursts • H2 as tracer of shocks and cooling of warm gas • Prospects (ALMA, etc.) Omont 2007, Rep. Prog. Phys. 70, 1-78 Solomon & Vanden Bout 2005 ARAA 43, 677

3. Important topics NOT to be addressed (* = still poorly documented) • - Local ULIRGs (Yu Gao) • Molecular absorption lines (mm, radio, UV) at high z • Lensing of high-z molecular lines • - * Special features of interstellar chemistry at high redshift •  Other molecules than CO (and H2 and PAHs) • * Evolution of nucleo-synthesis through molecular isotopes • - Host galaxies of the most distant QSOs(Ran Wang) • * Molecular outflows and AGN feedback • H2O mega-masers • Possible variation of fundamental constants measured with molecular lines: me/Mp through UV H2 lines, a through OH lines • - Etc.

4. Molecules are essential ingredient of the interstellar medium • Normal molecular gas: cold (~10-100K) and dense (~103-105 cm-3) •  Various steps of star formation: • - Giant Molecular Clouds • - Accretion disks • - Molecular outflows • - Photo-Dissociation Regions and Compact HII Regions • - Supernova remnants • Warm molecular gas: • - Shocks • - (+ UV or X fluorescence, stellar winds, etc.)

5. Molecules are essential ingredient of the interstellar medium • Rich molecular diagnosis • Velocityfields in dense, obscured gas dynamics: rotation, outflows (inflows), merging, shocks • Massof molecular gas. Dynamical mass of the galaxy • Temperatureprobe: Molecular ladder excitation through collisions (vs radiative processes): CO, NH3, etc. •  Other excitation (shocks, UV…) and cooling processes • Chemistry processes: formation/destruction: UV, Cosmic Rays, shocks, grains, X-rays, etc. • Abundances of elements and isotopes

6. General Features at high redshift • z > (0.5)-1  6…. (mostly ~2) - Cosmic times • D2 distance fading: ~105 from nearby galaxies to local ULIRGs (z~1). Another factor ~200 to z=2 •  Rudimentary information • Exceptional objects. Peak of starbursts and AGN • Metallicity/UV: harsh for molecules

7. Millimeter CO lines are by far the best tracer of molecular gas • H2 is hardly observable in cold gas • - IR lines are not excited and forbidden • - Absorption UV lines are too extincted

8. ------------------------- -------------------------- -------------------------- - --------------------------- ---------------------------- ---------------------------- ---------------------------- --------------------------- --------------------------- --------------------------- --------------------------- J = 10 275 K J = 9 250 K J = 8 180 K J = 7 140 K J = 6 105 K J = 5 75 K J = 4 50 K J = 3 30 K J = 2 15 K J = 1 5 K J = 0 0 K 260µm 1152GHz Rotational CO lines 520µm 576GHz Redshifted lines n = n0 /(1+z) 1.3mm 230GHz 2.7mm 115GHz

9. Millimeter CO lines are by far the best tracer of molecular gas • H2 is hardly observable in cold gas • - IR lines are not excited and forbidden • - Absorption UV lines are too extincted • CO millimeter lines are: • - the strongest millimeter lines • free from dust extinction • observable with heterodyne high velocity resolution • observable with high angular resolution with mm interferometers • - easy to excite in cold gas • - providing a good diagnostic of TK through multi-line studies • - roughly proportional to the mass of H2 • available in 3mm (1.3mm) atmospheric band at practically any redshift • - easy to observe at high z through an « inverse K-correction »

10. ------------------------- -------------------------- -------------------------- - --------------------------- ---------------------------- ---------------------------- ---------------------------- --------------------------- --------------------------- --------------------------- --------------------------- J = 10 275 K J = 9 250 K J = 8 180 K J = 7 140 K J = 6 105 K J = 5 75 K J = 4 50 K J = 3 30 K J = 2 15 K J = 1 5 K J = 0 0 K 260µm 1152GHz « Inverse K-correction » for CO lines  Redshifted lines n = n0 /(1+z) Line J ~ 1+z redshifted into the 3 mm best atmospheric band Line luminosity proportional to J3  strong increase of the 3mm line, almost compensating for the distance2 decrease Rotational CO lines 520µm 576GHz 1.3mm 230GHz 2.7mm 115GHz

11. Millimeter CO lines are by far the best tracer of molecular gas • H2 is hardly observable in cold gas • - IR lines are not excited and forbidden • - Absorption UV lines are too extincted • CO millimeter lines are: • - the strongest millimeter lines • free from dust extinction • observable with heterodyne high velocity resolution • observable with high angular resolution with mm interferometers • - easy to excite in cold gas • - providing a good diagnostic of TK through multi-line studies • - roughly proportional to the mass of H2 • available in 3mm (1.3mm) atmospheric band at practically any redshift • - easy to observe at high z through an « inverse K-correction » • However, • - complex CO line formation  uncertain MH2 • - limited angular resolution  uncertain Mdyn • - limited current sensitivity  massive objects = Submm Galaxies (SMGs)

12. 5 Molecular gas in Sub-Millimeter Galaxies (SMG) From the heritage of SCUBA To updated IRAM-PdBI Waiting for ALMA

13. SMGs: strongest starbursts in the Universe Essential steps of star formation in massive galaxies at z >~ 2 • Revealed by SCUBA surveys at 850µm (+ MAMBO at 1.2mm  AzTEC, LABOCA, BOLOCAM) Easy detection of dust FIR emission through « inverse K-correction », same flux at ~1mmfrom z ~ 0.5 to 10 • At least ULIRGs 1012 Lo  Numerous ~0.1-0.3 per arcmin2  Star Formation Rate SFR > 100 Mo/yr • Account for a significant fraction of submm background • Most exceptional HLIRGs 1013 Lo, 1000 Mo/yr nothing equivalent in the local Universe • Giant starbursts at the peak of star formation, z ~ 2-3  1-4, in massive proto-elliptical galaxies

14. Dissecting SMGs through mm CO lines at IRAM-PdBI • (Very) Large program at the IRAM Plateau de Bure millimeter interferometer (PdBI) (Genzel, Ivison, Neri, Tacconi, Smail, Chapman, Blain, Cox, Omont, Bertoldi, Greve et al.) • -30 SMGs with z~2-3 spectroscopic redshifts from radio positions (Chapman, et al.) • Detection and velocity profiles of CO(3-2) and (4-3) lines for 22 SMGs (Neri et al. 2003, Greve et al. 2005, Tacconi et al. 2006, Smail et al. in prep.). • Subarcsecond resolution imaging in progress (Tacconi et al. 2006, 2008, and in prep.) • Parallel programs for HST imaging and high resolution radio imaging with MERLIN • Key goals • - Physical properties and evolution of the SMG population • - How SMGs fit in general picture of galaxy evolution and formation

15. The Plateau de Bure Interferometer

16. CO Survey of submm Galaxies SMM J02396-0134 SMM J02399-0136 SMM J04431+0210 • 22 radio-detected submm galaxies with known optical/near-IR redshift detected in CO (March 2008) • 1<z<3.5 • Variety of profiles: 500-1000 km/s • SFR 500 - >1000 Msun/yr • MH2~ 3x1010 Msun • Mdyn ~ 1011 Msun SMM J09431+4700 SMM J13120+4242 SMM J14011+0252 SMM J16368+4057 SMM J16359+6612 SMM J16366+4105 • (Greve et al. 2005; Neri et al. 2004) • Detection with low angular resolution • High angular resolution: Tacconi+ •  SMM J16371+4053 ERO J16450+4626 SMM J22174+0015 (from P. Cox)

17. High angular resolution CO mapping at PdBI Example of mapping CO in an SMG at PdBI Case of an unresolved ~1kpc rotating disk (2008)

18. Examples of mapping CO in SMGs at PdBI Spatial and Kinematic Evidence for Mergers Double or multiple knots, with complex, disturbed gas motions Tacconi et al. 2008

19. Current conclusions of PdBI CO survey of SMGs • High CO detection rate, close to 100% with current PdBI sensitivity • Large fraction are resolved with subarcsecond resolution (2/3 are resolved in the radio with 0.3’’ MERLIN beam) • Mm lines of the molecular ISM, are unique to trace dynamical masses. (Also large stellar masses > 1011Mo) • SMGs are short-duration (~100 Myr) maximum starburst events in the evolution of a major gas-rich merger of massive galaxies. • Different combinations of ordered disk rotation and merger driven random motions and inflows • The high surface densities in SMGs are similar to compact quiescent galaxies in the same redshift range and much higher than in local spheroids.

20. 11 • The Spitzer Heritage for Molecules in Galaxies • Routine detection of PAHs at z~2 • PAHs are universal (in starbursts) at high z • 24µm bright SMGs and CO detection • Massive detection of H2 rotational lines

21. PAHs at highy redshift as tracers of starbursts PAHs are known to be an important component of the ISM Polycyclic Aromatic Hydrocarbons and related species are nano-particles from ~50 to a few 102 atoms, intermediate between conventional dust and molecules They are not individually identified, but display characteristic IR vibration features from C-H bonds and 2D C-lattice Orion

22. PAHs at highy redshift as tracers of starbursts PAHs are known to be an important component of the ISM Polycyclic Aromatic Hydrocarbons and related species are nano-particles from ~50 to a few 102 atoms, intermediate between conventional dust and molecules They are not individually identified, but display characteristic IR vibration features from C-H bonds and 2D C-lattice It is known from ISO that their bands dominate the mid-IR spectrum of galaxies. They are excited from UV fluorescence, and are thus interesting tracers of star formation The sensitivity of Spitzer InfraRed Spectrometer (IRS) at l~20-30µm allows routine detection of PAHs in 24µm-bright ULIRGs: z~1-2.5, in redshifted 6 to 11µm bands, especially 7.7µm PAH features are known to be relatively weaker in AGN, compared to hot dust continuum. PAHs are thus a good discriminant between starburst and AGN in high-z ULIRGs

23. Yan et al. 2007 Starburst vs AGN PAH spectrum Starbust Composite AGN-starburst

24. PAHs are universal in starbursts at high z Several 10^2 Spitzer/IRS spectra of 24µm sources 24µm bright z~2 starbursts Yan et al. 2007 St mJy Highest z, z=3.01 Huang+07

25. PAHs are universal in starbursts at high z Several tens of SMGs at z~2 SCUBA-MAMBO SMGs Valiante et al. 2007 Spitzer selected SMGs Average obs. spectra (and templates) Huang+ in prep.

26. Mid-IR spectral features (PAHs and silicates) are detected up to z=3 Hundreds of high-z spectra: • PAHsemission bands mostly in starbursts • Silicates in absorption 10µm (+18µm) in compact sources: AGN (+ starbursts) • Composite spectra are frequent • PAH features are weaker in AGN, but frequent, including classical bright high-z QSOs (Lutz et al. 2008) Yan et al. 2007

27. Questions • -------------- • Spitzer data are still very incomplete, many unpublished; their analysis is thus begining • PAH fraction and diagnostic • Modelling observed spectra (in relation with gas properties): • In starbursts: various types; environment • In AGN: • Central regions • Absorption/emission of the host galaxy • Winds: AGN/starbursts

28. 14 • Spitzer 24µm-bright SMGs • Only ~500 SMGs provided by SCUBA/MAMBO surveys( <~ 0.5-1 deg2) • AzTEC • Waiting for SCUBA2, Herschel, much larger(x>10) samples already exist in Spitzer wide field surveys, but difficult to identify • However, easy identification of a special subclass of z~2 SMGs, - large PAH/FIR ratio (strong 24µm) - large stellar mass (1.6µm-rest bump in SED not AGN-dominated) - ~50deg-2, in particular in SWIRE survey: 50 deg2 • With MAMBO/IRAMwe have confirmed they are SMGs by detecting • ~50-60 SWIRE z~2 starburst • ULIRGs/HLIRGsat 1.2mm • (Lonsdale+ 2008, Fiolet+ in prep. • Younger+ in prep.)

29. CO detection in Spitzer 24µm-bright high-z ULIRGs • Spitzer 24µm-bright SMGs are obvious targets for CO search, and • comparison with classical SMGs • However, because of limited mm bandwidth, need for optical • spectroscopic redshifts: difficult in ‘redshift desert’ z~1.7-2.0: • only a few redshifts determined • CO search in IRS sources of Yan et al. in progress at PdBI (Tacconi+ • in prep., Fiolet+ in prep. + Yan, Lutz, Fiolet, Cox, Sajina, Omont et al.) • Easy detection 8/8 observed sources: • - not only on PAH-dominated sources • - but on ‘composite’ AGN/starbursts, and even pure silicate- • absorption spectra (including radio loud ones)

30. MIPS16144 – Integrated CO 3-2 Emission strong PAHs strong MAMBO 1.2m flux (2.9mJy)  strong CO L. Tacconi in prep. ‘PAH’ source, Mambo flux=2.930.56, z=2.13 40 MHz spectral smoothing, rms=0.32 mJy/beam C-configuration

31. Fiolet et al. in prep. Weak 1.2mm MAMBO Srong 10µm silicate absorption Broad CO line Narrow CO line, radio loud

32. 17 CO in high z QSOs and the MBH/Mspheroid relation

33. CO in high z QSOs and the MBH/Mspheroid relation • High continuum 1.2mm detection rate of high-z luminous QSOs(55/200) • Omont +.1996, Carilli + 2001, Omont+ 2001, Omont + 2003, Bertoldi+ 2003, Beelen 2004, Wang+ 2007,2008 •  strong starburst in their host galaxies(practically all the ‘SMGs’ identified at z>4) • CO has been detected in at least 18 high-zQSOs with IRAM-PdBI • CO linewidth provides Mdyn x sin i • MBH may be estimated from broad optical lines, or Lbol • Coppin et al 2008 almost doubled the number of high-z QSOs with CO and MBH IRAM-30m + MAMBO camera Beelen+ 2004 CO(3-2) in J1409+5628

34. The ratio MBH/Msph of bright QSOs at z>~2 is larger than the local relation by an order of magnitude Six z~2 QSOs (i=20°) Coppin et al. 2008 Nine z~2-6 QSOs Shields et al. 2006

35. H2 at high redshift • H2 UV absorption lines in damped Lyman-α systems of quasars • Emission of H2 mid-IR rotation lines from warm molecular gas of various origin • Breakthrough of (ISO and) Spitzer on H2 emission in local sources (up to z~0.3) • Verma+ 2005, Rigopoulou+ 2002, Valentin & van der Werf 1999, Haas+ 2005:Various ISO results • Roussel et al. (2007)SINGS nearby galaxies • Higdon et al. (2006)Local ULIRGs • Ogle et al. ( 2006)Local radio galaxies • Johnstone et al. (2007)Cooling-flow clusters • Appleton et al. (2006)Galaxy-size shock in Stephan’s Quintet • Egami et al. (2006)IR-luminous brightest galaxy of Zwicky cluster3146 (z=0.3)  Many more unpublished results • However, no H2 rotation line has yet been confirmed at high z • H2 at high z is a major target for future space missions: JWST, SPICA, H2EX, etc. • H2 cooling is fundamental for the formation of the first galaxies from primordial gas • H2 (and HD) chemistry in primordial collapses is included in every model of formation • of first galaxies

36. 20 • The promises of upgraded IRAM-PdBI • (in 2007 PdBI has increased sensitivity by >~2 and baseline by ~2) • Further gain by 2009: larger bandwidth and more bands. • Sensitivity gain in continuum vs 2006 ~4-7 (20-50 in time!) (+ multi-line, uncertain redshifts, extended baseline…) •  Ambitious goals in high-z galaxies in pre-ALMA area: - Several large programs on SMGs, Spitzer galaxies, AGN, radio sources, etc. - More exploration of weaker sources: LBGs, BzKs, AGN, etc. - Multi-line studies • - Deep and ultra-deep fields. Identification of z>5 SMGs • - Systematic follow-up of Herschel (and SCUBA2 sources) • - Etc.

37. The promises of upgraded IRAM-PdBI • (in 2007 PdBI has increased sensitivity by >~2 and baseline by ~2) • Further gain by 2009: larger bandwidth and more bands. • Sensitivity gain in continuum vs 2006 ~4-7 (20-50 in time!) (+ multi-line, uncertain redshifts, extended baseline…) •  Ambitious goals in pre-ALMA area: - Several large programs on SMGs, Spitzer galaxies, AGN, radio sources, etc. - More exploration of weaker sources: LBGs, BzKs, AGN, etc. - Multi-line studies • - Deep and ultra-deep fields. Identification of z>5 SMGs • - Systematic follow-up of Herschel (and SCUBA2 sources) • - Etc. • Longer term: • Further bandwidth increase, up to 16 GHz (correlator) • Multi-beam receivers? • Double the number of antennas? • Ultimate goal: • Make the IRAM Interferometer the leading instrument on the • northern hemisphere with 30-50% ALMA sensitivity in the mm range

38. ALMA 50 12m-antennas  6 times the current PdBI collecting area Excellent site, full submm capabilities (compact array)  breakthrough • Comprehensive studies of high-z dusty starbursts in ALMA ultra-deep fields • Earliest starbursts in the Universe with deep fields, ‘gravitational telescopes’ and ALMA-JWST combined projects • Mapping all kinds of star-forming galaxies at all z: dust and mainly CO, • C+ and CI lines  structure and physical conditions • Blind z determination from CO. Multi-line detections in strong sources • Interstellar chemistry at all redshifts, including isotopomers, • Absorption lines with thousands of background sources  ISM in standard galaxies • Etc. First ALMA Science in 2010!

39. Prospects • JWST • MIRI/JWST will have orders of magnitude improvements in sensitivity, spatial and/or spectral resolution compared with Spitzer  synergy with ALMA • PAHs and H2 in varioustypes of high z galaxies • SKA (when high n bands are implemented) • Will be complementary to ALMA for studying the cold gas, detecting OH and H2O mega-masers and z>2 low-J lines of CO and other molecules • Herschel • Too small collecting area vs ALMA (/500!) for high-z molecules • But will detect 104’s of SMGs in wide surveys with full SEDs, LFIR and SFR • For follow up at PdBI and ALMA Herschel bands and SMG SEDs

40. 20 Questions to be addressed by observations of molecules in galaxies (at high z) • AGN-galaxy connection and BH growth • - Parallel evolution of AGN and starbursts. Host galaxies of obscured AGN. • - Molecular outflows and AGN feedback. Molecules associated with jets of radio galaxies • Origin of the MBH-s relation. Evolution with redshift • - Host galaxies of the first super massive black holes • - Physics of the central ISM in AGN host galaxies; molecular torus and accretion disk: H2O mega-masers, etc. • Fundamental physics and cosmology • - Possible variation of fundamental constants measured with molecular lines: me/Mp through UV H2 lines, a through OH lines • - H0 determination from H2O mega-masers • - Angular narrow-band correlations in CMB • Interstellar dust and nano-particules • - PAH properties in various galactic environments and redshifts • - (Origin of Diffusse Interstellar Bands) • Galaxy evolution • - Major evolution steps of the structure and star formation of massive galaxies • The first ULIRGs/HLIRGs at • z >5-7 • - Physics of the most extreme starbursts • - Physics of massive galaxy mergers • - What is the importance of very cold molecular gas • - Special features of interstellar chemistry at high redshift • - Evolution of nucleo-synthesis through molecular isotopes • - Early galaxy clustering at z>2 • - Galactic outflows in SMGs • - Galaxy size shocks: accretion shocks; cooling flows; galaxy and cluster collisons, • - Cooling of primordial gas in first (proto-)galaxies through H2 and HD

42. Cosmic Times z Dphot (Gpc) 1000 -------------------- 20 12 -------------------- z= 6 -------------------- z=2 ------------------- z=0.5 -------------------- z=0 • z >~ 20-30 Dark ages No stars, no galaxies • z ~ 6 – 15 ? Reionization • - First galaxies • First QSOs • z ~ 4 – 7 : • Current frontier • - Galaxy and Black-Holeearly assembly • - End of reionization • z ~ 1.5 -4: • - Peak of star formation • in massive elliptical galaxies • Peak of QSO activity • z ~ 0.5-1.5 : • Final phase of active SF • peak in spiral galaxies ~ 300million ~ 3.5 billion

43. Molecules are essential ingredient of the interstellar medium • Cooling through molecular lines • - Cold molecular gas: CO • - Warm: H2, H2O, CO  primordial gas: H2, HD • - (Heating through PAH photo-ionization) • Molecular masers: • OH, H2O  Mega-masers • Connection with interstellar grains • building molecular complexity • - H2 formation on grains • - Other chemical processes on grains. Accretion/desorption • - Polycyclic Aromatic Hydrocarbons (PAH) and related species • - Building molecular complexity  pre-biotic molecules?

44. General features at high z • Distance fading • Flux proportional to 1/DL2 (DL = Luminosity Distance) •  very large factor • “nearby” “local” high-z • galaxies ULIRGs, QSOs SMGs, QSOs • Redshift 0.001 0.1 2 • DL2(Gpc2) 2 10-4 0.2 40 [But additional factor when observing at fixed frequency n  emission at n0 = n(1+z)]

45. Prospects: SMGs in wide Herschel surveys • Full SEDs, LFIR and Star Formation Rate • Detection of tens of thousands SMGs • with full SEDs at maximum of FIR emission •  LFIR (and Tdust)  Star formation rate • Stacking analysiswith Spitzer, radio, etc.

46. Greve et al. 2005 Star formation @ z = 2.5 ▪ Submm bright Galaxy Population  MSB ? ▪ Single or merging LIRGs ? Tacconi et al. 2007 (from P. Cox)

47. Gain in Sensitivity / Time 2007 2008

48. The ‘dream’ Courtesy K. Schuster

49. The Current 5-year Plan

50. Early CO detections ….. and their improvements • CO has been detected at high z since 15 years • FIRAS 10214, Cloverleaf, BR1202-0725, APM 08279+5255,etc. • Significative improvements especially with new capabilities of PdBI • E.g. • - New map of CO(5-4) in • BR1202-0725 •  this rules out lensing and • confirms 2 HLIRGsat ~30-50kpc • - Multiple CO Lines 1.2mm dust map CO(5-4) 3mm spectra