1. Herschel
3.5m
IRAM Plateau de Bure 6  12 x 15m
H2O and other molecules in Herschel high-z galaxies. A new diagnosis of their dense cores
Alain Omont (IAP, CNRS & UPMC)
On behalf of Chentao Yang + H-ATLAS and IRAM Teams

2. OUTLINE
Introduction: Herschel high-z lensed submillimeter galaxies (SMGs)
H2O in local ULIRGs from Herschel spectroscopy
H2O ubiquitous emission in high-z (lensed) SMGs
Excitation of high rotational levels
 diagnosis of dense warm cores/clumps with strong IR
Detection of H2O satellite lines: H2O+
 chemistry of H2O formation
Complementary multi-line CO observations
Work in progress / Prospects:
- High-angular-resolution multiline mapping
- Probing outer galaxy layers with absorption lines
- High-J HCN, HCO+ & HNC in dense, star-forming gas.
- Bright future with ALMA

3. Herschel high-z lensed SMGs
Mm/submm is extremely powerful for detecting high-z sources
Herschel SPIRE surveys ( µm) have observed > 1000 deg2
They have detected >5 105 high-z SMGs
Half are luminous ULIRGs at z>1
(SFR >~ 300 Mo/yr, LFIR ~ 3x Lo)
Several 100’s are strongly lensed SMGs. Increased sensitivity by >~10
Lenses are easily identified among strongest submm sources versus local IRAS sources and blazars
Lens deflectors are mostly ellipticals at z ~ 0.2-1
Various mm/submm high-resolution maps with SMA, IRAM/PdBI, ALMA and lens models
High sensitivity used for line surveys: CO, CH+, H2O …

4. ~10 high-resolution PdBI maps: continuum + CO (or H2O)
SDP.81 ~1mm NC.143
PdBI+SMA mm
Comprehensive survey of ~30 submm lensed galaxies by
880µm SMA maps and lens models by Bussmann et al. 2013
NB.78

5. Continuum Source plane: cont.+CO(5-4) CO velocity structure
Revolutionary ALMA image of SDP81
in Science Verification ALMA Parnership 2015, Dye et al. 2015
Continuum Source plane: cont.+CO(5-4) CO velocity structure

6. H2O in local ULIRGs from Herschel spectroscopy

7. E.g. from Yang et al. 2013 (Herschel archive)
H2O in low-z ULIRGs
E.g. from Yang et al (Herschel archive)
H2O lines have been found very strong, mostly in emission, by Herschel (SPIRE-FTS, etc.) in 40 local (LIRGs/)ULIRGs,
in 7 H2O lines with Eup  600K
with intensity ~ next CO lines

8. H2O in low-z ULIRGs e.g. from Yang et al. 2013 (Herschel archive)
H2O lines have been found very strong, mostly in emission, by Herschel (SPIRE-FTS, etc.) in 40 local (LIRGs/)ULIRGs,
in 7 H2O lines with Eup  600K and various line ratios (excitation)
with intensity ~ next CO lines
LH2O roughly proportional to LIR  Excitation by IR
Reflects the complex structure of the galaxies (e.g. Lijie Liu + in prep.):
- mostly warm dense core more or less excited by IR
- (plus cold extended region, + hot core + ouflows + etc.)

9. H2O at high redshift in Herschel lenses

10. H2O at high redshift in Herschel lenses
Similar situation to low-z ULIRGs was expected in high-z ULIRGs (and HyLIRGs) up to 10 times more IR luminous without local equivalents
Therefore H2O lines should be easily detectable in strong lenses
- Main goal: detailed comparison of high-z SMGs with local ULIRGs
- First high-z H2O detections in Herschel lenses (Omont+2011,2013; Combes+2012) concomitant with confirmed H2O detections in historical lensed QSOs
 16 detections in H-ATLAS lenses at PdBI
Omont+ 2011, 2013, Yang+ 2016
 H2O seems strong in all Herschel lenses

11. H2O in H-ATLAS lensed sources Step 1: Detection
Low-lying line:
rest 752GHz Eu=137K
or rest 989GHz Eu=103K
7 detections reported in
Omont et al. 2013
9 new detections in
Yang (A&A submitted)
H2O is detected in all 16 observed H-ATLAS lenses
1.57 < z < 4.24

12. H2O in H-ATLAS lensed sources Step 1: Detection
Omont et al. 2013
Comparison with CO
PdBI CO: Cox, Ivison et al. in prep.
Striking similarities of line
profiles
 Same region of emission
 No strong differential lensing
Comparable H2O and low-J CO
intensities (but different l)
Similar H2O and adjacent high-J
CO lines (H2O/CO ~ 30-50%)

13. Additional detections 9/9 (16/16 in total)
H2O in H-ATLAS lenses
Step 1:
Additional detections
9/9 (16/16 in total)
Yang et al. 2016
H2O is strong in all
high-z ULIRGs
 detectable in all
lenses with PdBI
 strongest molecular
lines besides CO

14. Good correlation with LIR
Good correlation of LH2O with LIR, almost linear

15. H2O in H-ATLAS lensed sources
Step 2: H2O excitation
Excitation of high rotational levels
 diagnosis of dense warm cores/clumps with strong IR radiation

16. Observation of a higher excitation H2O line: J=3 Eup = 300K
Yang et al. in prep.
6 observed sources, 5 strong detections
Again quasi-linear
correlation of LH2O with LIR

17. Comparison of H2O excitation with local ULIRGs
Yang et al vs Yang et al. 2013
Variable but very comparable excitation of J=3 line with local ULIRGs

18. Diagnosis of galactic warm, dense cores/clumps
H2O excitation
Diagnosis of galactic warm, dense cores/clumps
Detailed modeling by Gonzalez-Alfonso et al. (2014)
Line ratios trace (in a complex way) conditions in emitting galactic dense cores/clumps :
- Infrared :dust temperature
- Infrared optical thickness
- H2O column density and abundance
- (Gas temperature TK and density n)

19. H2O excitation modeling
Models of Gonzalez-Alfonso+ 2014
Two lines J=2 + J=3 provide only
loose constains on Twarm & NH2O
Adding J=4 line would much
Improve
t100 is expected ~1-3(10?) from:
-scaling from local ULIRGs
-or extension of FIR emission
(~R~0.5-1kpc) and SFR  Mdensegas
-should be confirmed by
CO + continuum high-resolution
mapping
Twarm~45-75K depending on source
Typical H2O abundance ~10-6
Twarm
Twarm
+/-1s contours

20. H2O Excitation 2. Additional constraint on H2O
excitation from observation of
line (Eup/k = 450K)
Marginal detection of two sources
 relatively low excitation?

21. H2O+ as indicator of H2O chemistry/formation
In gas-phase, H2O can be produced through two routes:
Neutral-neutral reactions, usually related to shock, create H2O
O + H2  OH + H; OH + H2  H2O + H at high temperature
At lower temperature, the ion-neutral reaction in Cosmic Ray
Dominated Regions (CRDRs) and X-ray Dominated Regions
(XDRs) generate H2O from O, H+, H3+ and H2, with intermediates
such as O+, OH+, H2O+ and H3O+, and H3O+ + e  H2O + H.
Therefore, H2O+ lines are important for distinguishing
between shock- or ion chemistry origin for H2O in the early
universe

22. Detection of H2O+ in high-z Submillimeter Galaxies
Strong emission of two H2O+ lines observable close to a key H2O line
Seen in local galaxies
Easily detectablewith NOEMA Yang et al. 2016
Strong abundance of H2O+ is key for H2O chemistry
 Cosmic ray ion chemistry
H2O J= H2O+

23. Complementary multi-line CO observations
Complete study of CO achieved with IRAM/30m/EMIR
in 6 H2O high-z galaxies Yang+ in prep
(plus other by van der Werf+)
SLED
NOEMA proposal for higher-J study

24. Work in progress / Prospects:
- High-angular-resolution multiline mapping
- Probing outer galaxy layers with absorption lines
- High-J HCN, HCO+ & HNC in dense, star-forming gas
- Bright future with ALMA

25. High-angular-resolution multiline mapping
PdBI/NOEMA
2mm
Complex structures are expected for high-z SMGs, similar to, but possibly different from local ULIRGs
High angular resolution (+ lens modeling) mandatory to disentangle from lensed images
Confirmed by ALMA image of SDP.81
Even NOEMA may provide key information
CO maps of ~10 H-ATLAS lenses (Oteo+ in prep.)
SDP.81 ALMA
NOEMA maps of NC.143
Yang, Omont et al. in prep.
Continuum 1.2mm, 2mm
2 H2O lines, CO(10-9), H2O+
Work in progress
Evidence for strong differences in various images
SMA
0.88mm

26. Probing outer galaxy layers with absorption lines
Work in progress / Prospects
Probing outer galaxy layers with absorption lines
Absorption by cold extended
regions of the galaxy in lines
connected to the ground state
of H2O, H2O+ , OH, CH+, etc.
Dynamics: outflows, etc.
Marginal detection of H2O, H2O+
Spectacular detection of CH+
(+ very broad emission)
H2O H2O+ H2O+
CH+
H2O+
Falgarone et al. submitted to Nature
Yang et al. in prep.

27. High-J HCN, HCO+ & HNC in dense, star-forming gas
HCN(1-0) best tracer of dense star-forming gas (Gao et al.)
For high-z
HCN(1-0) observable at VLA
HCN higher-J plus HCO+, HNC, etc.) observable at mm l: ALMA, NOEMA
ALMA
Lupu+ HCN(3-2)
PdBI Yang+ HCN(5-4), HCO+(5-4), etc.
VLA
Gao, Yang +
HCN(1-0)

28. Need for ALMA deeper H2O studies in high-z SMGs
ALMA allows much deeper studies: H2O in unlensed SMGs, and comprehensive studies in lensed SMGs: excitation, structure, outflows, isotopologues, (+masers) etc.
The strong magnification of Herschel numerous lenses allows efficient surveys of much weaker molecular lines (H2O+, OH+, CH+, HF, HCN, HCO+, 13CO, CH3OH, etc.)  high-z astrochemistry
with NOEMA  ALMA
ALMA is crucial for high-resolution mapping to provide exquisite details about lens images and modeling and actual spatial structure of the sources and H2O excitation
ALMA is also mandatory for fine deep studies of line profiles, outflows, inflows, extended turbulence (see e.g. CH+ results in SDP17b by Falgarone et al.)
And also for isotopologues, minor species, etc.