1. Strongly lensed high redshift galaxies identified in Herschel wide surveys Prospects for ALMA observations Alain Omont (IAP, CNRS and Université Paris 6) On behalf of the H-ATLAS and HerMES Teams and the IRAM Team

2. Strongly lensed high redshift galaxies identified in Herschel wide surveys Prospects for ALMA observations Using gravitational magnification for studying Ultra-Luminous InfraRed Galaxies (ULIRGs) at high redshift Introduction - (Local ULIRGs) - High-z ULIRGs and the magic of the submm window - Mm/submm continuum & line studies of high-z ULIRGs: the promise of ALMA - Herschel wide surveys multiply by 100 the number of high-z ULIRGs identified - Herschel lenses increase the sensitivity by ~10 for studying high-z ULIRGs Herschel high-z strong lenses - Early studies of Herschel lenses - Prospects and Current status Example: H 2 O mm/submm lines at high z in Herschel lensed galaxies Examples of ALMA programs possible with Herschel high-z lensed galaxies

3. Arp 220: prototype of ULIRGs L IR = 1.4×10 12 Lo thought to be in the final stage of merging radio & NIR imaging  double nuclei projected separation ~300 pc M H2 ~ 10 10 M o within central kpc in accord with simulations of galaxy mergers M 82: prototype of LIRGs, 3.2 10 11 Lo Strong mid-IR PAH emission, even in strong outflow Most high-z ULIRGs seem to have IR SEDs similar to M 82 Arp 220 M 82

4. ULIRGs observed with the WFPC2 of the HST at optical wavelengths. Many of these ULIRGs are merging galaxies See Steve Lord’ s talk

5. SMGs: strongest starbursts in the Universe Important players of star formation at z >~ 2  ULIRGs are much more numerous at high redshift than locally factor close to 1000 at z=2  Revealed by SCUBA surveys at 850µm (+ MAMBO at 1.2mm  AzTEC, LABOCA, BOLOCAM)  « Sub-Millimeter Galaxies » (SMG)  Easy detection of dust FIR emission through « inverse K-correction », same flux observed at  ~ 1mm from z ~ 0.5 to 10

6. from Bertoldi, Voss, Walter L FIR (Lo) = 4x10 12 S 1.2mm (mJy) FIR emission of cold dust (T d ~ 30-40 K) : - steep submm spectrum - compensates for distance - S practically independent of z from z ~ 0.5 to 10 Effect often known as « negative K correction » Redshift degeneracy Dust detection: The Magic of the high-z submm window SPIRE

7. ULIRGs and Star Formation at high-z ULIRGs dominate star formation at z>~2 SMGs (and Herschel/SPIRE) sources are luminous ULIRGs They provide only a small fraction of total star formation > ULIRGs > z=2 SMGs SPIRE sources Lindner+ 2011Le Floch+ 2005 1.2mm Total Spirals LIRGs ULIRGs

8. SMGs: strongest starbursts in the Universe Important players of star formation 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 ~1mm from z ~ 0.5 to 10  Giant starbursts at the peak of elliptical formation z ~ 2-3  1-4  A few 10 12 Lo: at least ULIRGs  ~1 per 3-5 arcmin 2  Most exceptional HLIRGs 10 13 Lo  ~1 per 50-100 arcmin 2 nothing equivalent in the local Universe probably in most massive DM halos  progenitors of BCG/cD galaxies of clusters?  Only ~1000 SMGs provided by SCUBA/MAMBOASTEC/BOLOCAM surveys ( <~ 1-2 deg 2 )  Herschel surveys are detecting several 10 5 SMGs

9. IRAM-PdBI Mm/submm studies of high-z ULIRGs - High extinction makes optical/NIR studies of high-z ULIRGs hardly feasible - Extinction is practically negligible in mm In addition to continuum, molecular mm lines are key tool for high-z ULIRG studies  CO lines are the strongest and most important (but C + ): They give the mass of molecular gas M H2 (Rotation) velocity profile Spatial extension of molecular gas  dynamical mass Rotation line ladder (SLED)  T K + n H2  multi-T K gas  AGN excitation of high-J lines  HCN is the best tracer of dense gas and star formation  H 2 O traces warm, dense gas and very strong IR  C + (very strong, very high freq.) traces diffuse, (partially) ionized gas

10. IRAM-PdBI In addition to continuum, molecular mm lines are key tool for high-z ULIRG studies  CO lines are the strongest and most important (but C + ): They give the mass of molecular gas M H2 (Rotation) velocity profile Spatial extension of molecular gas  dynamical mass Rotation line ladder (SLED)  T K + n H2  multi-T K gas  AGN excitation of high-J lines  HCN is the best tracer of dense gas and star formation  H 2 O traces warm, dense gas and very strong IR  C + (very strong, very high freq.) traces diffuse, (partially) ionized gas ALMA

11. PdBI CO high-resolution study of SMGS Tacconi et al. 2008 Compact post-mergerResolved pre-merger

12. HERSCHEL See Steve Lord’ s talk Space Observatory, ESA (+NASA)  3.5m dish  3 instruments: 5 Camera-photometer, FTS -SPIRE -SPIRE 250-500µm wide surveys  1000 deg 2 ~4 x 10 5 high-z ULIRGs - PACS 70-160µm Heterodyne -HIFI  May 2009  January-March 2013

13. Herschel high-z extragalactic wide surveys  H-ATLAS  H-ATLAS 550 deg 2  HerMES 70 deg 2 deeper + 270 deg 2 shallow Both mostly SPIRE (250, 350, 500µm) close to confusion limit  Plus PACS surveys: smaller areas, deeper HLS: lensing clusters, 100 deg 2 overlap with SPT (South Pole Telescope) AKARI/NEP ? etc.

14. H-ATLAS PIs Eales & Dunne 550deg 2

15. The HerMES survey SPIRE Guaranteed Time; PIs Seb Oliver & Jamie Bock ~900h(Multi-level Deep fields ~5 deg 2 ) Wide fields ~70 deg 2 Practically all Spitzer wide fields: SWIRE (Lockman, ELAIS-N1, ELAIS-N2, XMM-LSS, CFDS, ELAIS-S1) + FLS, Bootes, AKARI-ADFS practically all observed mostly SPIRE (250, 350, 500µm) practically at the confusion limit somewhat deeper than H-ATLAS multi- ancillary data  + HeLMS 270 deg 2 shallow, equatorial, RA ~ 0

16. without optical IDs with optical IDs Herschel surveys revolutionize the field of high-z submm galaxies Several 10 5 s high-z sources Half H-ATLAS sources have z>1 (inverse K-correction) All high-z sources are ULIRGs with SFR > 300 Mo/yr and L FIR > 10 12 Lo Some Herschel/SPIRE sources are warmer than SMGs and not detected at ~1mm Some cold SMGs not detected by Herschel Lapi et al. 2011

17. Herschel lenses increase the sensitivity by ~10 for studying high-z ULIRGs The power of gravitational lensing Since 20 years lenses mark the frontier of mm radioastronomy

18. Gravitational lensing « Einstein Cross » Einstein ring QSO (radiogalaxy) Cloverleaf QSO X-Ray optical

19. Unlensed SMGS Neri+ 2003 Lensed Cloverleaf Thanks to magnification factor µ ~11 - CO lines are more intense by ~10 than in unlensed SMGs - High S/N HCN & HCO+ lines are detected while they are out of reach in unlensed SMGs with current PdBI sensitivity The power of gravitational lensing

20. Cloverleaf The power of gravitational lensing Since 20 years lenses mark the frontier of mm radioastronomy Rowan-Robinson’s galaxy FIRAS10214Swinbank’s Eyelash SMMJ2135 APM08279+5255

21. Herschel lenses increase the sensitivity by ~10 for studying high-z ULIRGs Herschel high-z strong lenses Early studies of Herschel lenses Prospects and Current status

22. Negrello et al. 2010 Submm wide surveys are ideal for finding high-z lenses -High-z submm sources are very strong (‘inverse K-correction’) - Very steep unlensed counts  Almost half of the strongest SPIRE sources are high-z lenses  Very easy to identify from local galaxies (+ blazars) radio unlensed lensed Local galaxies

23. (faint) Early studies of Herschel high-z strong lenses 1.H-ATLAS SDP Field Negrello et al. Science 2010 ~14.4 deg 2 7000 sources Brightest 500µm sources: 11 sources with S 500μm > 100 mJy 4 nearby galaxies (z<0.05), + 1 blazar, 1 galactic blob  5 high z candidates confirmed redshifts z = 1.5 – 3.4

24. SED of lens candidates in H-ATLAS S DP field clear cases of double-source SEDs z~0.2-0.8 elliptical galaxy + high-z ULIRG Negrello+2010

25. ID15.141 Submm photometric redshifts Ratios S 250 /S 350 & S 350 /S 500 plus a template such as Arp220  submm z-phot Good agreement with z CO for 6 sources with z CO A good value of z-phot is important for searching z CO with a limited bandwidth Adding 1.2mm MAMBO flux helps: S 1.2mm =10-40mJy Dannerbauer+ Measuring z CO at z>~4 is difficult with Zspec, impossible with Zpectrometer  PdBI, EMIR or CARMA blind search e.g. ID15.141

26. Zspec Lupu et al. to be submitted to ApJ Redshifts have been confirmed with PdBI or CARMA interferometers

27. Best, highest-z H-ATLAS SDP lenses Sub-Millimeter Array images at 870µm Extended images: gravitational arcs on top of the lens galaxy Red 870µm contours on top of I Keck image

28. Extended images: gravitational arcs on top of the lens galaxy from Negrello ESLAB2010 Idealized gravitational arcs

29. S. Serjeant

30. (faint) Early studies of Herschel high-z strong lenses 2.H-ATLAS prominent z=4 lens ID15.141 Cox et al. 2011

31. Z = 4.24

32. (faint) Early studies of Herschel high-z strong lenses 3. HerMES SDP exceptional lens HerMES Lockman-01 = HLSW-01 Very wide image Riechers et al. 2011 PdBI, SMA & CARMA maps K. Scott et al. 2011 Z-Spec spectroscopy Gavazzi et al. 2011 lensing modeling

33. HerMES Lockman-01 = HLSW-01 PdBI + SMA Riechers+ 2011

34. Prospects for studies of Herschel high-z strong lenses A simple extrapolation of 5 lenses in 15 deg 2 H-ATLAS SDP yields ~200-300 similar lenses in total in ~1000 deg 2 Herschel surveys This number may be much increased by lowering the flux limits, e.g. by a factor >~5 for S(350µm) > 80 mJy Work is in progress for extensions of lens identifications: - larger areas - lower flux limits - use of additional data, e.g. NIR surveys for identifying the deflectors One may thus expect thousands of Herschel high z lenses, including ~50-100 lensed sources in which the magnification is > 10

35. Prospects for studies of Herschel high-z strong lenses The two main applications of Herschel lenses should be: 1. Deep studies of high-z lensed sources (see below e.g. for H 2 O, ALMA ) 2. Studying the evolution of dark matter halo of the deflectors - Most deflectors are massive spheroids with a few spirals and groups - Redshifts of the deflectors are found mostly between z = 0.2 and 1, with a significant fraction at z>1. This is much higher than for the deflectors of optical lenses - A major goal is thus to check the evolution of dark-matter halos at z~ 1 In addition Herschel wide surveys are important tools for cosmological studies, through map fluctuation studies, etc. (see e.g. Cooray+ 2010)

36. Work in progress on Herschel high-z strong lenses Enormous amount of work for identifying and following up hundreds of Herschel lenses  2/3 of observations carried on; half of them well processed  Several hundreds: identified candidates planned HST snapshots  Several tens: 1mm observations  PdBI next Winter CO redshifts  PdBI next Winter Identifications of deflector candidate with z-phot  About 10:High-resolution mm/submm images  PdBI next Winter High-resolution optical/NIR (HST, Keck-AO…) Spectroscopic redshifts of deflector Lens models  About 5: Other lines than CO (and CI): H 2 O, C +  PdBI next Winter Multi-line CO SLED  IRAM-30m next Winter

37. H 2 O mm/submm lines at high z - Strong H 2 O emission in the nuclei of local ULIRGs - H 2 O in high-z lensed QSOs - H 2 O in Herschel lenses - Prospects H 2 O is one of the most abundant molecules in the ISM - In cold clouds practically all in ice on grains abundance up to ~10 -4, 1/3 of total oxygen - Desorbed into the gas in hot cores No confirmed detection of H 2 O at high z prior to 2011

38. H 2 O in local ULIRGs (Mrk 231) H 2 O is one of the most abundant molecules in the ISM - In cold clouds practically all in ice on grains abundance up to ~10 -4, 1/3 of total oxygen - Desorbed into the gas in hot cores But it is very difficult to observe in the gas: - Needs to be desorbed from the grains - At low z: H 2 O lines are completely absorbed by water in the Earth atmosphere  space - At high z: H 2 O lines are very weak without lensing amplification No confirmed detection of H 2 O at high z prior to 2011

39. Strong H 2 O emission in the nuclei of local ULIRGs Compact single- double-nuclei (+AGN) of major mergers see talks by D. Sanders and others  Prominent FIR H 2 O absorption lines in local ULIRGs (+AGN) such as Arp220, Mrk231… (ISO; Herschel Gonzalez-Alfonso +2011 ) Evidence for high H 2 O abundance from H 2 18 O, and high 18 O/ 16 O ratio (Gonzalez-Alfonso+2011, Martin+2011)  Herschel/SPIRE: spectacular submm emission lines e.g. Mrk231 (obscured QSO) (van der Werf+ 2010) -Several H 2 O lines up to E exc ~600K -Strong lines comparable to CO (very different from M82 and PDR) - Plus high-J CO (strong), [CI], H 2 O +, OH +, HF, CH +, [NII], etc.

40. Van der Werf et al. 2010 GHz

41. Gonzalez-Alfonso+ 2010 SPIRE van der Werf+ 2010 CO J 15 14 13 12 11 10 9 8 7

42. Strong H 2 O emission in the nuclei of Mrk 231  Prominent FIR H 2 O absorption lines in local ULIRGs (+AGN):Arp220, Mrk231 Evidence for high H 2 O abundance from H 2 18 O, and high 18 O/ 16 O ratio  Herschel /SPIRE: spectacular submm emission lines e.g. Mrk231 (van der Werf+ 2010) - Several H 2 O lines up to E exc ~500K, - Strong lines comparable to CO (very different from M82) - Plus high-J CO, [CI], H 2 O +, OH +, HF, CH +, [NII], etc.  Implications ( Gonzalez-Alfonso+ 2010 ): - Lower levels may be excited by warm dense gas (~100K, ~10 6 cm -3 ), with high H 2 O abundance (>~10 -6 ) - Higher levels imply intense FIR excitation in few 100s pc - Possible role of shocks, AGN (XDR), CR excitation, but unclear  High z: Many objects similar to MrK231 are expected, but very few detections of H 2 O are reported up to now  Herschel lenses

43. H 2 O lines must be easily detectable in many Herschel lenses Herschel SPIRE 250/350/500 µm surveys (~1000deg 2 ) are ideal to find rare, high-z strongly lensed SMGs Negrello+2010 Only 1-2 deg 2 observed by ‘traditional’ SCUBA/MAMBO/ASTEC surveys  practically no strong lens Breakthrough by Herschel surveys  hundreds of strong high-z lenses (while only ~6 found before Herschel) Unique opportunity for deep studies of high-z mm/submm lines As performed with classical mm lenses, e.g. the Cloverleaf H 2 O line intensities are a significant fraction of that of CO lines in Mrk 231. They should be easily detectable in strongly lensed similar high-z ULIRGs Negrello+ 2010

44. PdBI detection of H 2 O in H-ATLAS SPD-17b z = 2.305 ZSpec H 2 O tentative detection Lupu et al. 2011 H-ATLAS SPD-17 identified as lensed ULIRG by Negrello+ 2010 Complex HST image (Negrello+ in prep.) Rich spectrum: high-J CO  z=2.308  L app ~4 10 13 Lo Possible H 2 O 2 02 -1 11 at 299GHz: seems very strong but noisy (2.6  )

45. PdBI detection of SPD-17b at 299GHz z=2.3 Omont et al. 2011 A&A 530, L3 GHz km/s Compact D-conf. Continuum 32+/-2 mJy (+ extended A,B Confs. not yet fully processed)

46. Detection of H 2 O in H-ATLAS G12-29 z= 3.3 One of the strongest Herschel lensed sources: S 500µm = 285 mJy, even detected by Planck Z-Spec/APEX spectrum (Lupu+ in prep.) impressive high-J CO lines up J=10-9 (11-10?)  z~3.254 Confirmed with Zpectrometer 3.2588±0.0012 Strong line at 273.3GHz H 2 O 3 21 -3 12 needed to be confirmed 273 GHz is not currently observable with PdBI, but another strong H 2 O line is expected at 231.96 GHz (in a bad ZSpec channel) (H 2 O is also tentatively detected at 257.7GHz ) PdBI Detection of H 2 O 2 02 -1 11 Preliminary results (R. Neri) C-conf., 6 antennas Very robust detection I ~ 5 +/-0.55 Jy.km/s ~ I(SPD.17b) / 2  ~same luminosity 231.96 GHz  z = 3.260 Width 680 km/s

47. Lensed images of G12-29 Multi-galaxy deflector The K image is very different from ~1mm images Keck K-band SMA 870µm PdBI 1.3mm continuum + H 2 O

48. 5 other detections of H 2 O in high-z sources (at IRAM 2011, except Cloverleaf) Multi-line detection in the lensed QSO APM08279+5255 z = 3.9 van der Werf et al. 2011, plus Lis et al. 2011, Bradford et al. 2011 Zspec tentative detection in the lensed QSO Cloverleaf z= 2.56 Bradford et al. 2009 Plus recent detections of two other Herschel sources and one QSO

49. Inferred conclusions for H 2 O in high-z ULIRGs The detection of H 2 O implies special excitation conditions in an intense IR field and a warm dense gas, similar to Mrk 231 with higher luminosity The high H 2 O/CO ratio makes it unlikely that the H 2 O emission originates in classical PDRs But all the evidence suggests that SDP.17b, G12-29 and Mrk 231 have similar properties, with warm, dense gas and strong IR field ( plus possibly shocks, XDR, CR). However, this needs to be confirmed by higher excitation lines of H 2 O  ALMA

50. Prospects for H2O studies in Herschel lenses (with ALMA)  (Full) ALMA will easily detect H 2 O multi-lines in hundreds of Herschel high-z lenses (filler in ALMA Cycle 0 for 3 sources, and search for H 2 O in 8 additional H-ATLAS lenses is scheduled at 18 PdBI next Winter)  Together with high-J CO lines, H 2 O lines will provide rich information about the conditions in the dense warm ISM of the compact merger nuclei of SMGs, and their strong FIR, plus shocks, X Rays, Cosmic Rays, etc.  The full ALMA sensitivity will also allow detection of weaker lines or details of H 2 O lines such as: - Absorption lines - Outflows - Isotopologues H 2 18 O, H 2 17 O (possibly HDO, D 2 O?) - Other molecules detected in Mrk 231: OH +, H 2 O + (related to H 2 O and allowing diagnostic of XDR chemistry), HF, etc. - And many other molecules allowing, together with H 2 O, further checks of the ISM of merger nuclei for their physical conditions, chemistry, dynamics, AGN influence, etc.

51. ALMA 50 x 12m dishes + ACA array 7m dishes

52. Prospects, strategy and questions for ALMA There will be 100’s of strongly lensed sources available for ALMA - Object selection in function of goals - Systematic studies of specific classes if populated enough - Muli- studies: EVLA, JWST, HST, etc. This would allow in particular to populate rare classes of objects for comprehensive ALMA studies, e.g. - highest redshifts, z>4 even z>5 - strong AGN of various types - radio loud - L IR > 10 13 Lo, L IR <10 12 Lo - H 2 O mega-masers - cluster lensing - extremely strong amplification, etc. Studies of the lensing galaxies through ALMA observations will have important cosmological applications But detailed lensing models are needed for inferring properties of lensed SMGs Anyway, ALMA will have a fantastic time with such sources!

53. Examples of ALMA programs possible with Herschel lenses Blind CO redshift determination and the highest redshifts - Finding redshifts for 100’s sources remain a major issue - Searching for z~>~6 objects (lensed or not) is specially important ALMA high-resolution imaging of strong lenses - ALMA can do that in the continuum, CO lines & C + line (+H 2 O lines, etc.) - Structure of the ISM and SF; AGN molecular torus - Dynamics: rotation, M dyn, mergers, outflows, etc. High sensitivity molecular (and atomic) spectroscopy - H 2 O, HCN...: diagnostic - etc.: chemistry, isotopologues Golden objects with two background sources lensed by the same galaxy, making possible cosmological tests that are independent of the mass of the lens.

54. ALMA Cycle 0 Projects on Herschel high-z strongly lensed galaxies  Accepted (top 10%) - 0.53’’ resolution snapshot mapping at 870µm of 30 HerMES lenses (Riechers et al.) - Comprehensive study of a z=1 H-ATLAS lens (Orellana et al.)  Fillers - Multi-line H 2 O study in the three high-z H 2 O sources visible from ALMA (van der Werf et al.) - Dense gas tracers (HCN,HCO+ …) in H-ATLAS SDP sources (Lupu et al.) - High-resolution mapping of a cluster-lensed high-z source (Egami et al.)

55. Summary Herschel surveys will observe ~1000 deg 2 First lens identifications and intensive follow-up confirm that one may expect hundreds of lensed SMGs with magnification ~5-10  Unique legacy for mm/submm studies of molecular gas in high-z major starbursts (ULIRGs even below the confusion limit) Effective sensitivity increase by ~10 for ALMA, IRAM/NOEMA etc. for studies of high-z ULIRGs H 2 O is an important tracer of compact, dense warm, strong-IR nuclei of SMGs, especially obscured AGN New step in studying high-z lensing and their dark matter structures at higher deflector redshift up to z >~ 1 But needs much follow-up and high-quality lensing modeling