FIR-SubMm Astronomy The crucial transition region between The crucial transition region between Optical/IR and Mm/Cm wavelengths That can be investigated with That can be investigated with Ground-based and Space-Based telescopes With “mixed” detection techniques With “mixed” detection techniques

IAC-IR/SubMm 2006-ThdG 2 FIR/SubMm Wavelength Range TeraHertz Frequency Range Domain of: 1. Cool and Cold Universe and…… Physics 2. Molecular emission and Absorption Rot/Vibrational transitions 3. Atomic and Ionic lines Planck Curves Also in Earth Atmosphere!!

IAC-IR/SubMm 2006-ThdG 3 Atmospheric transmission at CSO and Chajnator APEX

IAC-IR/SubMm 2006-ThdG 4 FIR/SubMm Spectral Line Surveys CSO Spectrum of Orion: 8 nights Spectral survey of Orion-KL showing hundreds of molecular lines with atmospheric transmission overlaid. HIFI will be able to survey outside of the atmospheric windows and at frequencies never probed before, allowing for searches of new molecules. Spectral Survey IRAS16293 JCMT Spectral Survey IRAS16293

IAC-IR/SubMm 2006-ThdG 5 ntensity FIR Unique Science: Water abundant from SWAS, ODIN, ISO, Spitzer, etc Velocity (km/s) 1.9E E E E E-16 W cm -2  m -1 o-H 2 O V LSR (km/s) T A * (K) relative warm H2O ISO-SWS ISO- LWS SWAS

IAC-IR/SubMm 2006-ThdG 6 FIR Science: Water in Comet Lee-- in Martian Atmosphere SWAS Results

IAC-IR/SubMm 2006-ThdG 7 FIR Science: Water towards Sgr B2 and Arp 220 SWAS Results ISO-LWS Results

IAC-IR/SubMm 2006-ThdG 8 IR Spectroscopy of Interstellar Molecules: >120 molecules detected so far (Wootten)

IAC-IR/SubMm 2006-ThdG 9 FIR Science: The (unknown) Molecular Universe: FIR Science: The (unknown) Molecular Universe: Searching for low-lying vibrational transitions of large molecules

IAC-IR/SubMm 2006-ThdG 10 IR Spectroscopy of Interstellar Molecules: Cycle of Organic Molecules in the Universe: Interstellar Organics are formed in ISM Gas, Stellar Outflows and on Dust Grains; Organic material integrated in Solar System, chemically processed/destroyed; In Final Stage of Stars, dust and elements are returned to the ISM; Organic molecules may have seeded the Earth during this cycle

IAC-IR/SubMm 2006-ThdG 11 Hydrides, atoms and ions Atom/IonTransition Freq. (GHz) 12 C 3 P J= P J= C 3 P J= P J= C + 2 P J=3/2- 1/ C + 2 P J=3/2- 1/ N + 2 P J= N + 2 P J= Mg 3 P J= P J= HydrideTransitionFreq (GHz) PH 3  -, N= HBrJ= CH 2  3/2,J=3/2-  1/2,J=1/ o-H 2 OJ KaKc = NH 3 J K = HClJ= SiH 2  1/2, J=3/2-1/ ? CH + J= p-NH 2 J KaKc = NH 3  - N= OH + J= p-H 3 O + J K = NH + 2  1/2,J=3/2-1/ HFJ= SH 2  3/2,J=5/2-3/ HFe o-H 3 O + J K = OH 2  1/2,J=3/2-1/

IAC-IR/SubMm 2006-ThdG 12 Two Main Detection Schemes for Astronomical Sub-/mm Radiation Incoherent detection  direct detectors (bolometer) total power detection no phase information  used on single antenna low spectral resolution Coherent detection  heterodyne receiver frequency down conversion high spectral resolution phase information  single antenna and interferometer

IAC-IR/SubMm 2006-ThdG 13 Thermal BB Background emission for emissivity= 0.04; Resolution=10. Note the two natural backgrounds: - Zodiacal IR - Interstellar dust - Below for Resolution=1000. Detector Sensitivity expressed in Noise Equivalent Power (NEP) Radiation Power in Watts for 1 Hz electrical detection bandwidth where SNR~1

IAC-IR/SubMm 2006-ThdG 14 Specific technical problems for (F)IR Direct Detection Influence Sky background Influence Sky background Atmosphere: transmission and emission Atmosphere: transmission and emission Zodiacal, background within a few AU Zodiacal, background within a few AU Galactic Galactic Stability telescope: (pointing included) Stability telescope: (pointing included) Thermal stability (of emitting surface) Thermal stability (of emitting surface) Stability instrument: Stability instrument: Thermal Thermal Electrical (i/f noise) Electrical (i/f noise) Mechanical pathlength Standing waves Mechanical pathlength Standing waves Remedy and Elimination techniques: Remedy and Elimination techniques: high resolution (wavelength/angular) high resolution (wavelength/angular) Beam switching (faster) Beam switching (faster) Position switching Position switching Frequency switching Frequency switching

IAC-IR/SubMm 2006-ThdG 15 Cooling Techniques for FIR/SubMm Astronomy Cryostats Cryostats Bath cryostat for liquids (N > 77K; He > 4.2K) Bath cryostat for liquids (N > 77K; He > 4.2K) Cryostats for solid cryogens ( H2 > ~20K) Cryostats for solid cryogens ( H2 > ~20K) (IRAS, ISO, WIRE, Spitzer, Herschel, …) (IRAS, ISO, WIRE, Spitzer, Herschel, …) Closed cycle (mechanical) coolers Closed cycle (mechanical) coolers Disadvantages: vibration, power consumption; lifetime,.. Disadvantages: vibration, power consumption; lifetime,.. Staged approach: for example: 70K; 20K; 4K; 0.2K) Staged approach: for example: 70K; 20K; 4K; 0.2K) (Planck, Astro-F, ODIN, …) (Planck, Astro-F, ODIN, …) Radiation (Passive) cooling: Radiation (Passive) cooling: Toward deep space (2.7K) T exp3 dependence Toward deep space (2.7K) T exp3 dependence (SWAS, JWST, SPITZER, …) (SWAS, JWST, SPITZER, …)

IAC-IR/SubMm 2006-ThdG 16 Cryostat and typical IR Satellite

IAC-IR/SubMm 2006-ThdG 17 IR/Submm telescope design requirements. Ambient telescopes: Minimal blocking Minimal blocking No warm elements in f.o.v. (baffles,..) No warm elements in f.o.v. (baffles,..) Secondary mirror undersized Secondary mirror undersized Wobbling secondary (atmosphere) Wobbling secondary (atmosphere) Cryo/cooled telescope: No background contribution if cool enough, No background contribution if cool enough, Reflection/transmission counts. Reflection/transmission counts. Baffles also cooled. Baffles also cooled. Scondary mirror larger is not a problem (Cassegrain,.. ) Scondary mirror larger is not a problem (Cassegrain,.. ) Heterodyne recievers: off-axis Heterodyne recievers: off-axis

IAC-IR/SubMm 2006-ThdG 18 Direct Detection Detector Characteristics: A) Photon Detectors: respond to photons A) Photon Detectors: respond to photons (semiconductors and superconductors) (semiconductors and superconductors) B) Thermal Detectors: absorb photons and thermalise the energy (bolometers) B) Thermal Detectors: absorb photons and thermalise the energy (bolometers)

IAC-IR/SubMm 2006-ThdG 19 TES RÖNTGEN MICRO-CALORIMETERS Eén Beeld Element (Pixel) Energie Spectrum 5 x 5 pixel Röntgen camera 32 x 32 pixel Röntgen camera PRINCIPLE

IAC-IR/SubMm 2006-ThdG 20 Principle of Heterodyne Mixing // 0f IF LO RFIF Heterodyne principle = mixing of two frequencies (signal + local oscillator) to produce (sum and) difference signal (intermediate frequency = IF) Mixing needs non-linear element (e.g. diode, SIS junction) = mixer RF Lower sideband (LSB) Upper sideband (USB) freq f IF = | f LO - f RF | Double sideband mixer: both sidebands converted to same IF Single sideband mixer: Only one sideband converted to IF Sideband separating mixer: two sidebands converted to different IF outputs

IAC-IR/SubMm 2006-ThdG 21 Heterodyne Radiation Detection Combine strong LO signalV LO = cos(  Lo t) + A weak RF signal V S = cos(  S t+  ) Gives total power absorbedP ~ V S V LO cos((  S -  Lo )t +  )+…. !! Amplitude and phase information conserved in IF signal !! Detect radiation at frequencies where no amplifiers are av!!ailable IF signal

IAC-IR/SubMm 2006-ThdG 22 Block Diagram of a Heterodyne Receiver to correlator or spectrometer Astronomical RF signal (e.g. 650 GHz) Optics SIS mixer Local oscillator IF amp(s) LO ref in 4 K IF signal out (e.g. 4 GHz) LO signal (e.g. 646 GHz) Components:  Optics Mixer Local Oscillator (LO) Calibration source IF amplifier(s) Dewar and cryogenics Bias electronics Spectrometer(s) Cal source

IAC-IR/SubMm 2006-ThdG 23 Heterodyne Signal Chain Convert incoming radiation into electronic signal (IF) for further processing Spectral information is preserved (Δf/f determined by backend) Heterodyne Instrument Spectrometer/ Correlator Data acquisition “Front End”“Backend” Intermediate Frequency (IF) optical electrical

IAC-IR/SubMm 2006-ThdG 24 Wide Band Spectrometer The WBS is an Acousto-Optical Spectrometer that covers the 4 GHz instantaneous bandwidth in 4 sections. The spectral resolution is 1 MHz. This is equivalent to 0.6 km/s at 480 GHz and 0.15 km/s at 1.9 THz

IAC-IR/SubMm 2006-ThdG 25 Wide Band Spectrometer: proto-type Proto-type Model of the WBS

IAC-IR/SubMm 2006-ThdG 26 Heterodyne Principle

IAC-IR/SubMm 2006-ThdG 27 Multi-Colour HIFI

IAC-IR/SubMm 2006-ThdG 28 In Context: (F)IR Missions IRAS ISO SPITZER Astro-F 2006 JWST-MIRI Herschel SPICA? The FIRM Ultimates? SAFIR SOFIA? SWAS Odin

IAC-IR/SubMm 2006-ThdG 29 ~ arcsecs with few K sensitivity ~ 10 arcsec with micro-K sensitivity Beyond Herschel?? Closing the FIR Spatial Resolution Gap Herschel ESPRIT

IAC-IR/SubMm 2006-ThdG 30 Beyond Herschel?? Higher Sensitivity with cold Optics/Instruments and improved Detectors

IAC-IR/SubMm 2006-ThdG 31 Herschel Spacecraft Characteristics; telescope diameter 3.5 m telescope diameter 3.5 m telescope WFE < 6 m telescope WFE < 6 m telescope temp < 90 K telescope temp < 90 K telescope emissivity < 4% telescope emissivity < 4% abs/rel pointg (68%) < 3.7” / 0.3” abs/rel pointg (68%) < 3.7” / 0.3” science instruments 3 science instruments 3 science data rate 130 kbps science data rate 130 kbps cryostat lifetime 4.0±0.4 years cryostat lifetime 4.0±0.4 years height / width ~ 7.5 / 4 m height / width ~ 7.5 / 4 m launch mass ~ 3200 kg launch mass ~ 3200 kg power ~ 1500 W power ~ 1500 W orbit ‘large’ Lissajous around L2 orbit ‘large’ Lissajous around L2 solar aspect angle deg solar aspect angle deg launcher (w Planck) Ariane 5 ECA launcher (w Planck) Ariane 5 ECA

IAC-IR/SubMm 2006-ThdG 32 Herschel observatory capabilities Photometry - imaging, 6 broad bands in µm range Photometry - imaging, 6 broad bands in µm range PACS - simultaneous 2 colour fully-sampled (0.5F) imaging with FOV 1.75x3.5 arcmin with R~2.5 centred at 75/110 and 170 m PACS - simultaneous 2 colour fully-sampled (0.5F) imaging with FOV 1.75x3.5 arcmin with R~2.5 centred at 75/110 and 170 m SPIRE - simultaneous 3 colour 2F imaging with FOV 4x8 arcmin with R~3 centred at 250, 363, and 517 m SPIRE - simultaneous 3 colour 2F imaging with FOV 4x8 arcmin with R~3 centred at 250, 363, and 517 m for larger fields ‘on-the-fly’ mapping, mosaicing for larger fields ‘on-the-fly’ mapping, mosaicing sensitivity is somewhat wavelength and observing mode dependant, very roughly for point sources 1mJy - 1 - 1 hour; for mapping confusion limit is important sensitivity is somewhat wavelength and observing mode dependant, very roughly for point sources 1mJy - 1 - 1 hour; for mapping confusion limit is important Spectroscopy - in µm range, varying R in range Spectroscopy - in µm range, varying R in range PACS - 5x5 spatial x16 spectral pixels, FOV 0.8 arcmin, R~1500, ~ m PACS - 5x5 spatial x16 spectral pixels, FOV 0.8 arcmin, R~1500, ~ m SPIRE - FTS spectrometer, R ~ , FOV 2.6 arcmin, ~ m SPIRE - FTS spectrometer, R ~ , FOV 2.6 arcmin, ~ m HIFI - heterodyne spectroscopy with R up to 10 7, ~ and m, 2 orthogonal polarisations, 4000 spectral channels per polarisation, single pixel on the sky, mapping by ‘on-the fly’ or mosaicing observations HIFI - heterodyne spectroscopy with R up to 10 7, ~ and m, 2 orthogonal polarisations, 4000 spectral channels per polarisation, single pixel on the sky, mapping by ‘on-the fly’ or mosaicing observations

IAC-IR/SubMm 2006-ThdG 33 Herschel PACS Instrument Imaging photometry Imaging photometry two bands simultaneously (60-85 or µm and µm) with di-chroic beam splitter two bands simultaneously (60-85 or µm and µm) with di-chroic beam splitter two filled bolometer arrays (32x16 and 64x32 pixels, full beam sampling) two filled bolometer arrays (32x16 and 64x32 pixels, full beam sampling) point source detection limit ~4 mJy (5, 1h) point source detection limit ~4 mJy (5, 1h) Integral field line spectroscopy Integral field line spectroscopy range µm with 5x5 pixels, image slicer, and long-slit grating spectrograph (R ~ 1500) range µm with 5x5 pixels, image slicer, and long-slit grating spectrograph (R ~ 1500) two 16x25 Ge:Ga photoconductor arrays (stressed/unstressed) two 16x25 Ge:Ga photoconductor arrays (stressed/unstressed) point source detection limit 3…20 x W/m 2 (5, 1h) point source detection limit 3…20 x W/m 2 (5, 1h) Focal Plane Footprint 32 x 16 pixels 6.4” x 6.4” 64 x 32 pixels 3.2” x 3.2”

IAC-IR/SubMm 2006-ThdG 34 Instrument concept Imaging photometry Imaging photometry two bands simultaneously (60-85 or µm and µm) with dichroic beam splitter two bands simultaneously (60-85 or µm and µm) with dichroic beam splitter two filled bolometer arrays (32x16 and 64x32 pixels, full beam sampling) two filled bolometer arrays (32x16 and 64x32 pixels, full beam sampling) point source detection limit ~3 mJy (5, 1h) point source detection limit ~3 mJy (5, 1h) Integral field line spectroscopy Integral field line spectroscopy range µm with 5x5 pixels, image slicer, and long-slit grating spectrograph (R ~ 1500) range µm with 5x5 pixels, image slicer, and long-slit grating spectrograph (R ~ 1500) two 16x25 Ge:Ga photoconductor arrays (stressed/unstressed) two 16x25 Ge:Ga photoconductor arrays (stressed/unstressed) point source detection limit 3…10 x W/m 2 (5, 1h) point source detection limit 3…10 x W/m 2 (5, 1h) 32 x 16 pixels 6.4” x 6.4” 64 x 32 pixels 3.2” x 3.2” Focal Plane Footprint

IAC-IR/SubMm 2006-ThdG 35 FPU/optics Chopper sGeGaDetector Red Spectrometer Blue Bolometer Red Bolometer Calibrator I and II 0.3 K Cooler Filter Wheel I Filter Wheel II Grating GeGa Detector Blue Spectrometer Encoder Grating Drive Entrance Optics Photometer Optics Calibrator Optics Slicer Optics Spectrometer Optics

IAC-IR/SubMm 2006-ThdG 36 PACS Photodetectors for spectroscopy 16x25 pixel Ge:Ga extrinsic photoconductor filled arrays 16x25 pixel Ge:Ga extrinsic photoconductor filled arrays 25 linear modules of 16 pixels (stressed/unstressed 25 linear modules of 16 pixels (stressed/unstressed integrated cryogenic readout electronics (CTIA/multiplexer) integrated cryogenic readout electronics (CTIA/multiplexer) background-noise limited performance expected background-noise limited performance expected Red Array (stressed Ge:Ga) Blue Array (unstressed Ge:Ga) with baffle housing

IAC-IR/SubMm 2006-ThdG 37 CRE Photoconductor Arrays (Spectrometer) Two 25x16 pixel filled arrays Two 25x16 pixel filled arrays Extrinsic photoconductors (Ge:Ga, stressed/unstressed) Extrinsic photoconductors (Ge:Ga, stressed/unstressed) Integrated cryogenic readout electronics (CRE) Integrated cryogenic readout electronics (CRE) Near-background- noise limited performance expected Near-background- noise limited performance expected

IAC-IR/SubMm 2006-ThdG 38 PACS Bolometer Arrays (Photometer) Two filled arrays: 64x32 pixels (blue) and 32x16 pixels (red) Two filled arrays: 64x32 pixels (blue) and 32x16 pixels (red) Bolometers and multiplexing readout electronics operating at 0.3K Bolometers and multiplexing readout electronics operating at 0.3K Near-background-noise limited performance measured (FM) Near-background-noise limited performance measured (FM) Blue focal plane Photometer unit with blue + red focal planes and 3 He cooler Pixel

IAC-IR/SubMm 2006-ThdG 39 Predicted PACS Instrument Performance Photometer Sensitivity Photometric Bands wavelength [µm] filter transmission (10'x10' in 1 day) on-array chopping/ line scanning off-position chopping wavelength [µm] [mJy] (point source; 5  /1h) Spectrometer Resolving power wavelength [µm] on-array chopping off-position chopping Spectrometer Sensitivity [W/m 2 ] (5 , 1 hour) wavelength [µm] (…but cosmic rays)

IAC-IR/SubMm 2006-ThdG 40 SPIRE Detector Arrays: 300 mK NTD Ge Bolometer Arrays with 2F Feedhorns 520  m 43 detectors 360  m 88 detectors 45 mm  m 19 detectors  m 37 detectors Photometer Spectrometer  Coincident beam centres 250  m 139 detectors

IAC-IR/SubMm 2006-ThdG 41 SPIRE NTD Ge Bolometer Arrays NEP ~ 3 x W Hz-1/2120-K Si JFET readout 1/f noise knee < 100 mHz

IAC-IR/SubMm 2006-ThdG 42 HIFI Instrument: Top Level Requirements and Resulting Concept Heterodyne spectroscopy Heterodyne spectroscopy single pixel on the sky single pixel on the sky very high spectral resolution very high spectral resolution 7 dual-pol mixer bands 7 dual-pol mixer bands GHz ( m) 5x2 SIS mixers, GHz ( m) 5x2 SIS mixers, IF 4-8 GHz GHz( m; 2x2 HEB mixers, GHz( m; 2x2 HEB mixers, IF GHz 14 LO sub-bands 14 LO sub-bands LO source unit in common LO source unit in common LO multiplier chains LO multiplier chains 2 spectrometer systems; 2 spectrometer systems; for each polarisation for each polarisation - auto-correlator spectrometer - acousto-optical spectrometer Angular Resolution (with Herschel): 12”- 40” HIFI designed for: - Spectral Scans and Spectral line surveys - Very high spectral resolution - Widest possible coverage in the unexplored FIR/Submm range 1.Frequency coverage: 480 – 1250 GHz ( m) 1410 – 1910 GHz ( m) 2. Sensitivity Near-quantum noise limit sensitivity IF bandwidth/Resolution: - 4 GHz (in 2 polarisations) – 280 kHz –0.5 and 1 MHz 3. Calibration Accuracy: 10% baseline; 3% goal

IAC-IR/SubMm 2006-ThdG 43 Heterodyne principle

IAC-IR/SubMm 2006-ThdG 44 Latest update LO chain performance All bands: development has been completed. all have been delivered except bands 3 (January)

IAC-IR/SubMm 2006-ThdG 45 IF-1 CA Y Two IF frequencies:10 x IF-1 high (4-8 GHz) for SIS mixers 4 x IF-1 low ( GHz) for HEB mixers IF-1 high (CAY) and low (SRON) designs finished and compliant QM / FM contracts placed and running with Alcatel (Spain) IF-1 development