HIFI performance & science

1. HIFI performance & science Frank Helmich – Principal Investigator for HIFI

2. Overview • HIFI performance - time line/overview/lessons learned • Ground - Instrument level testing, Integrated system tests and Thermal Balance/Thermal Vacuum tests • HIFI performance in orbit – CoP, PV and calibration • SEU treatment • Calibration error budget • Science results

3. HIFI performance - ground • At the time of the HIFI proposal some components had low TRL • Before the DM a toy model of the Common Optics Assembly was made, several mixer designs tried, several mixer options explored for HEB, etc • At DM a reasonable test program could be executed – luckily no choice between HRS and WBS made • The QM program was way too short. HIFI had to deliver the QM to industry, who were not ready to use it in their own test program -> major impact on the FM test program • FM program was very intense, but most goals were reached • IST was good preparation for flight – WBS comb problem found • TB/TV time needed absolutely necessary since the impact of the too short QM program needed to be recovered • It is worth to start large missions even if not all technology is ready • Projects like Herschel benefit from stringent ESA-management and a strong ESA team to overcome difficulties in the development

4. HIFI in pictures

5. HIFI performance – in-orbit • CoP and PV very intense period with good results • OD81 anomaly • New CoP for redundant started in January 2010 • New PV – completely reorganized and rushed shortly thereafter • Observing started in April 2010 • As a result of the anomaly engineering, PV and routine calibration was intertwined for a long time • The 10 MHz crystal (MO) for HIFI has a dedicated heater circuit – circuit is failing since June 2010 – no impact on science • The WBS comb is fading – cross correlation with HRS is ready as operational procedure • SEU’s impact the LCU memory once every 13 days – some impact on science

6. SEU’s until now 6

7. SEU treatment • Procedures are now in place at MOC, HSC and at SRON covering all possibilities of SEU’s in either ICU or LCU • The loss in science time has been occassionaly two days/event but generally HIFI is not ON when SEU’s occur • We even did a LCU power cycling, potentially dangerous for the redundant LCU, with no adverse effects • We expect that some science time will still be lost in the future but we have done everything to minimize the effect

8. HIFI calibration • Parameters: • System temperature: very consistent over FM to flight program • Load coupling: established in ILT • Hot and cold load temperature: verified in flight • Side-band ratio: established in ILT, fine-tuned in flight • Optical performance (beamwidth, aperture efficiency, point source coupling, etc.): basis achieved in ILT, fine-tuning in flight • Planetary models: ESA and instruments effort • Standing wave analysis: Done mainly on flight data • Pointing analysis: common activity with ESA, PACS and SPIRE

9. HIFI calibration – System temperature

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11. Band 2 – clear deviation at lower frequencies 11

12. Aperture efficiency and HPBW Determination of aperture efficiency and beam widths have been measured Band 5 results under investigation 12

13. Relative error budget (in percent)

14. Error budget continued • In most cases the limits given are upper limits – we are not able to determine in tests the absolute value of the parameters better than that upper limit – worst case • However, you can be considered very unlucky if you hit any of these upper limits • Consistency checks on spot frequencies show that HIFI spectra are the same within 10% • HIFI data goes to level 2 in the pipeline immediately • HIFI level 2 data is generally directly useable for science • HIFI is by far the best heterodyne instrument around in: frequency coverage; sensitivity and in reliability • HIFI can be considered a major success!!

15. HIFI Science • Life-cycle of gas and dust in the Universe • Emphasis on star-formation • Physics • Chemistry • Our proxies are dust, molecules, atoms and ions • Our measurement tools are spectral lines and shapes

16. First Herschel / HIFI observation (21 june 2009) H2O 110-101 (557 GHz) line Absorption: ~ 20 % deep, ~6 km/s

17. The absorption is not formed in Saturn • If from Saturn, would have to be from levels higher than ~ mbar (where emission comes from) • TB continuum ~ 115 K  TB (line core) ~ 90-95 K • No such temperature exists in Saturn’s stratosphere • Even if it did, no water can exist at 90-95 K • Line width ~1/3 of what expected from rotational broadening • Absorption was not seen by SWAS in 1999 • The ring and satellite system were seen wide open in 1999 ( = -21°) • They were almost edge-on in 2009 ( = -4°) • Absorption probably occurs from material near to equatorial plane  Enceladus torus Bergin et al, 2000

18. Observations from June 2010 and models:sensitivity to column density

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20. Orion KL Methanol Wang et al., 2011, A&A,527, 95 20

21. Sgr B2 N 21

22. NH2 11110-11011 12111-12012 1019-10010 918-909 817-808 NH2 716-707 110-101 615-606 514-505 211-202 413-404 312-303 HNCO 22

23. Sgr B2 N 23

24. H2O 321-212 CO 10-9 H2S H2O+ H2O+ p-NH3 o-NH3 HF p-H2O 24

25. H2O lines: HIFI’s raison d’être Red: HIFI Blue: PACS Observe mix of low- and high-excitation lines to probe cold and hot environments 25

26. Surprise:broad and weak H218O lines Absence of narrow H218O lines, also for higher J, limit water abundance in inner envelope Note that these deep observations down to a few mK do not reveal other lines in WBS than those expected from common molecules (except in HM hot cores) Abundance H2O: high in outflow (10-5-10-4) but low in outer envelope (~10-8) Inner envelope (<10-5) 26

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28. L1448 outflow: H2O vs CO: if it moves we see it! Nisini et al. in prep 28

29. Molecule hunting • Scanning the frequency range of HIFI looking for new lines -> new insights in chemistry and physical conditions IRAS16293-2422 OMC2-FIRS4 Lower: methanol; Upper NH2

30. HF in the ISM: dark gas Orion KL W49N Sgr B2 (M) W51 Sonnentrucker et al. 2010, A&A, 521, L12 Phillips et al. 2010, A&A, 518, 109 van der Werf et al. 2010, A&A, 518, L42 30

31. NEW MOLECULES: H2CL+, H2O+, OH+ • Chloronium detected in absorption toward NGC6334I and Sgr B2(S). • Predicted by chemical models, but column densities ~100 times higher. • OH+ and H2O+: reactive cations that play key role in the oxygen chemical network in UV irradiated regions. Lis et al. 2010, A&A, 521, L9 Ossenkopf et al. 2010, A&A, 518 Neufeld et al. 2010, A&A, 521, L10 Schilke et al. 2010, A&A, 521, L11 31

32. O2 in Orion shock from OTKP “HOP”– Paul Goldsmith 32

33. Conclusion • I thank all of the people who have been working on HIFI hardware and software in the last decade – these are more than 300 men and women • I thank all the scientists for making the great Key Programmes and for their eagerness to do the data reduction and analysis • I thank the colleagues from ESA and SPIRE/PACS for the close collaboration on all aspects of the mission • I thank industry for the collaboration and for providing the platform world-class instruments can use to the best • Reminder: All of us have now started to work on the next challenge: SPICA-SAFARI, which holds great promises for astrophysics, promises we have seen to come true for Herschel and its instruments