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Information about menten

Published on November 15, 2007

Author: Rafael


Slide1:  (Sub)millimeter Astronomy with Single-Dish Telescopes – Now and in the Future Karl M. Menten (Max-Planck-Institut für Radioastronomie) Slide2:  Submillimeter Astronomy – Major science drivers: The cosmological submm background – the star formation history of the universe at high z Structure and energetics of molecular clouds Star and planetary system formation Astrochemistry the Solar System Slide3:  Single dish vs. interferometer? Basic facts: (If you can calibrate your phases) an interferometer is much better to detect faint (point-like) sources Single dish observations are necessary to provide short- spacing information Bolometer arrays will become very large (thousands of elements) Many dozen times the collecting area of ALMA and, thus, very much faster if noise not dominated by systematics (atmosphere) and if the confusion limit is not reached Heterodyne arrays will have ~100 elements at 3 and 2 mm and dozens at submm wavelengths Slide4:  Advantages of array receivers: Mapping speed Mapping homogeneity (map lage areas with similar weather conditions/elevation)  minimize calibration uncertainties. Slide5:  The Galactic Center Region as seen by SCUBA at 850 m The power of (bolometer) array science: Bolometer arrays have completely dominated the field of submillimeter continuum observations for ~20 years now Talks by: Borys, Glenn, Greaves, Johnstone, Kauffmann Posters by: Aguirre, Carpenter, Dowell, Li, Sutzki, et al. Slide6:  The sub-mm Extragalactic Background resolved: Hughes et al. 1998 Slide7:  Bolometer arrays are getting ever larger: yesterday very soon 2006? In addition: MAMBO-II, Bolocam, SHARC-II, … Slide8:  12’ x 12’ (14“ FWHM) rms 1 – 4 mJy 16 sources > 4  15 sources between 3.5 and  < 4 at 450 m: 5 sources > 4 850 m The HDF-North SCUBA Super-map Obviously still far from confusion limit Slide9:  Cumulative Number Counts [deg-2] Confusion limit ist ~0.7 mJy (3) at 850 m. To cover 1 square degree with 5120 bolometers with 100 mJy s-1/2 takes ~40 hours. Slide10:  ALMA will be crucial to get positions accurate enough for optical spectroscopy ( redshifts), maybe even determine redshifts on its own. Accurate position determinations via VLA are currently a bottleneck, as each source requires many hours of observing time. … and no VLA for the southern hemisphere. Spitzer positions might save the day! Slide11:  Fundamental innovations in bolometer technology/observing Superconducting bolometers Superconducting TES (Transition Edge Sensors) thermistors SQUID multiplexer integrated with the bolometers on the wafer SQUID readout amplifier Much reduced complexity, greater sensitivity Much larger bolometers possible Slide12:  Fundamental innovations in bolometer technology/observing “Fast scanning” (= no chopping) Made possible by changes in read-out electronics (DC- biased/AC- coupled  AC-biased/DC-coupled) DC-coupled electronics allow much faster scanning (scanning speed was limited by 2 Hz chopper frequency) No chopper means faithful imaging of large structures free choice of scan direction less complexity new observing modes Technique successfully used at SHARC-II/CSO Slide13:  Bolometer array sizes will ultimately (= soon) be limited by the field of view of the telescope. SCUBA–II will completely fill its. Possible solutions: Telescopes dedicated to large RX array operation? e.g. off-axis antenna/modified Gregorian design (South Pole Telescope; see (p. 33 ff) Radically new, different optics designs possible? The LSST, a telescope designed for a 3° field:  The LSST, a telescope designed for a 3° field 8.4 m diameter f/1.25 cryostat Cryostat window diameter: 1.28 m Not feasible for radio astronomy  huge sidelobes Slide15:  APEX Cassegrain optics N. Halverson/E. Kreysa Slide16:  HERA = HEterodyne Receiver Array Heterodyne arrays are becoming available just now: Slide17:  Important: Uniform beams Uniform TRX and TRX not “much” worse than TRX of state-of-the-art single pixel RX Common sense requirements: Schuster et al. 2004 Slide18:  Factor ~160 in resolution! Schuster et al. 2004 Ungerechts & Thaddeus 1987 Slide19:  16 elements 325 – 375 GHz 14" FWHM Slide20:  7 pixels frequency range 602 – 720 and 790 – 950 simultaneously beamsize 9" – 7" and 7" – 6" IF band 4 – 8 GHz CHAMP+ Carbon Heterodyne Array of the MPIfR Slide21:  Important: Uniform beams Uniform TRX and TRX not “much” worse than TRX of state-of-the-art single pixel RX Common sense requirements for any array RX: All of the above superbly met by MMIC array spectrographs! Slide22:  focal plane array: 4×4 pattern. currently mounted on the FCRAO 14m telescope Will be moved to the LMT fixed tuning => best performance at all frequencies being expanded to 32 elements InP MMIC pre-amplifiers: 35-40 dB gain band (Tsys=50 – 80 K) instantaneous bandwidth: 15 GHz (85 – 115.6 GHz with only two local oscillator settings) Slide23:  W-band (80 – 116 GHz) Science with MMIC Array Spectrographs (MASs) Apart from CO J=1-0 lines there are ground- or near-ground-state transitions of HCN, HNC, CN, N2H+, HCO+, CH3OH, SiO… all between 80 and 115 GHz Because of their high dipole moments, these species trace high density gas, n > 104 cm-3 ( CO: n > 102 cm-3) Large-scale distribution of these molecules on larger GMC scales poorly known Strong emission in these lines, as well as in rare C18O isotope, traces high column densities ( star formation) These lines are very widespread (= everywhere) over the whole Galactic center region (-0.50 < l < 20) Slide24:  Other most interesting projects include complete (mostly) 12CO and 13CO mapping of nearby galaxies. These are HUGE (many square arc minutes)! Such maps would be interesting in their own right and are absolutely necessary as zero spacing information for CARMA, the PdBI, and ALMA. REALLY FANTASTIC would be MASs on CARMA and the PdBI!!! … and they would make these facilities highly competitive in the ALMA era, as ALMA will (probably) not have MASs for a very long time. Slide25:  Sensitivity With the IRAM 30m telescope at 90 GHz it would take 25/N hours to produce a Nyquist-sampled map of area one square degree with an N element MAS at an rms noise level of 0.2 K and a velocity resolution of 1 km/s. const 1 for 8/10 bit sampling  FFT spectrometers! Slide26:  New Backend Option: Fast Fourier-Transform (FFT)-Spectrometers Principle: Direct sampling of RX IF with 8/10 bit resolution Continuous FFT calculation with given window function (to suppress side lobes) Calculation of power spectrum Power spectrum averaging Slide27:  Overwhelming advantages of FFT Spectrometers:  FPGAs: Field-Programmable Gate Arrays ADC with 8 or 10 bit sampling (ACs: 2bit) higher sensitivity, no need for total power detectors Much higher dynamic range  Leveling much simpler  simplification of IF module 100% mass production chips  no custom made chips  much better reacion to markets  take full advantage of Moore’s law very high channel numbers: Today: 1 GHz/32768 channels Soon (1 – 2 yrs): 2 GHz/65536 channels Very high degree of integration: Integration of a complete spectrometer(digital filters, windows, FFT, power builder and accumulator) of one chip (AC’s use cascaded chips  can be re-programmed much lower power consumption (more reliable) B. Klein Slide28:  40 x 1 GHz (40 x 32768 channels)  = 30 kHz  v = 0.03km/s@300 GHz 32 x 0.8 GHz (32 x 1024 channels)  = 1 MHz  v = 1km/s@300 GHz FFTS Slide29:  SEQUOIA is just the beginning: MMIC Array Spectrographs (MASs) will soon (within a few years) have ~100 elements and somewhat later have many 100s of elements Large MMIC FPAs currently being developed at JPL (PI Todd Gaier) driven by cosmology (T. Readhead)/space (FFTS) backends will be available With LOs integrated, MASs will revolutionize large areas of molecular line astronomy Question: Will HEMTs become competitive at shorter λλ? Slide30:  Mapping speed and sensitivity estimates indicate that very large sections (if not all) of the Galactic plane can be imaged HUGE advantage over SiS arrays: Many lines in HEMT band can be imaged simultaneously Necessary Spectrometer capability: Example W-Band: Want to do 20 lines simultaneously need ~300 km/s (= 100 MHz) each Need N  20  100 MHz = N  2 GHz 2 GHz FFTS bandwidth cost ~ 40 kEU today/MUCH less next year At today’s prizes, an FFTS for a 100 element array would cost 4 MEU HOWEVER: Above is the de luxe correlator. To save money, could do fewer lines, use narrower bandwidths Also: Remember Moore’s Law!!! Actually, FFTS prizes are falling hyper-Moore these days Expect 3 kEU/GHz very soon Slide31:  The same spectrometer serving a multi-element MAS would also allow very wide band spectral line surveys toward single positions Slide32:  3 mm region (70 – 116 GHz) in 500 MHz chunks 4000 – 5000 lines!!!! (Belloche, Comito, Hieret, Leurini, Menten, Müller, Schilke) With a HEMT RX this would have taken 2 LO settings  Factor ~100 savings in observing time Slide33:  FFT-Spectrometers – Timeline and Perspectives: 2005/MPIfR: Development of an FFT Spectrometer with 16384 channels 500 MHz bandwidth SUCCESS: Brought into operation at the 100m telescope (April 2005) and (1GHz/32768channels) at APEX (June 2005)!  FFTS Technology available today! Slide34:  FFT Timeline – Perspectives (cont'd): 2005 – 2009: Doable today(!): 3 GHz BW using three cascaded ADCs @ 2GS/s (10- bit) and analog input BW of ~3.3 GHz FFT-Processing: continuous 4 GS/s with 64.000 channels in one high-end Xilinx-Chip (XILINX VII Pro70) (Study by RF-Engines). Cost: kEU 15 – 20 for 1 GHz BW (Hardware) ca. 90 kEUR (one time only) for Xilinx-programming Firm RF-Engines: Slide35:  Timeline – Perspectives (cont'd): > 2009: Complexity of Xilinx chips doubles every 14 – 18 months ► Costs: Grow linearly with each RX element Minimal serial production costs by simple reproduction of system Slide36:  FFTSs and MASs Synergy – Pooling resources FFTSs: Bernd Klein, MPIfR, Collaboration with Arnold Benz (ETH Zürich/Acqiris) Potential “users” for FFTSs and MASs (= possible co-financers): IRAM APEX LMT Effelsberg 100m telescope GBT Madrid 40m telescope, Sardinia Telescope + ... Slide37:  Submillimeter Facilities in the high Atacama desert: ASTE – The Atacama Submillimeter Telescope Experiment 10m NAO Japan, Tokyo U., Osaka Prefecture U., U. Chile  Talk by H. Ezawa (next) Nanten-2 4m Nagoya U., Osaka Prefecture U., Seoul National U., Cologne U., Bonn U., U. Chile APEX – The Atacama Pathfinder Experiment Slide38:  The APEX telescope Built and operated by Max-Planck-Institut fur Radioastronomie Onsala Space Observatory European Southern Observatory on Llano de Chajnantor (Chile) Longitude: 67° 45’ 33.2” W Latitude: 23° 00’ 20.7” S Altitude: 5098.0 m 12 m  = 200 m – 2 mm 15 m rms surface accuracy currently (June 2005) in final testing phase First facility instruments: 345 GHz heterodyne RX 295 element 870 m Large Apex Bolo- meter Camera (LABOCA) Slide39:  Bolometers LABOCA-1: 295-channel at 870 µm (MPIfR, Bochum U., IPHT Jena) FOV: 11', beam 18” (same as MSX and Herschel 250µm) 37+-channel at 350 µm (MPIfR) 324-channel at 1.4/2 mm for Sunyaev-Zel'dovich survey (UCB, MPIfR) new software: BoA (Python/F95) Heterodyne 183 GHz water vapour radiometer 210-270 GHz (OSO) 270-375 GHz (OSO) 375-500 GHz (OSO) 460/810 GHz dual channel First Light Apex Submillimeter Heterdyne Rx (FLASH) 800-900 GHz (MPIfR/SRON, PI) CHAMP+ 600-720/790-920 GHz, 2×7-elements (MPIfR, PI) FIR receivers: up to 1.5 THz = 200 micron (OSO, Köln) Instrumentation Slide40:  Two Major Apex projects: APEX-SZ A 870 m Survey of the Galactic plane Concrete projects (Start: Late 2005) Concept Slide41:  Big Bang 0 379,000 yr z=1089 today 14 Gyr time The Sunyaev-Zel'dovich Effect Zhang, Pen, Wang 2002 Slide42:  SZ X SZ differential surface brightness is independent of redshift. Carlstrom et al. APEX beam at 2mm (40") ~ BIMA beam at 1 cm UCB/APEX SZ Array :  UCB/APEX SZ Array 1.4fλ horns coupled array 330 bolo’s in 6 wedges Each TES bolometer coupled through resonant circuit to SQUID readout direct path to Multiplexing 150 GHz and 217 GHz by swapping horns & filters 14 cm Slide44:  Simulations by M. White Slide45:  The APEX Sunyaev-Zel'dovich Galaxy Cluster Survey Basu Beelen Bertoldi/Co-PI Kreysa Menten Muders Schilke Cho Dobbs Halverson Holzapfel Kermish Kneissl Lanting Lee/Co-PI Lueker Mehl Plagge Richards Schwan Spieler White Sunyaev Böhringer Horellou a collaboration between MPIfR and U.C. Berkeley in association with RAIUB, MPE, MPA, OSO, … Zhang, Pen, Wang 2002 Discover and catalog several 1000 galaxy clusters in a mass limited survey: map 200 deg2 to ~10 mK rms per ~60" pixel. Constrain cosmological parameters and dark energy equation of state, w. SZ contribution of z>10 Supernova-remnants. Observe evolution of structure, and test theories of structure formation. Study clusters in detail: structure, evolution, galaxy populations. Study CMB secondary anisotropies, weak lensing, Ostriker-Vishniac effect, quadratic Doppler effect, etc. A Galactic Plane survey with APEX :  A Galactic Plane survey with APEX F. Schuller, K. M. Menten, P. Schilke, F. Wyrowski Max Planck Institut für Radioastronomie The APEX Galactic Plane survey Survey definition:  The APEX Galactic Plane survey Survey definition Sensitivity: reach 1 Msun in nearby regions, and a few 10 Msun in Galactic Center Gas mass in cores using Hildebrand (1983) and standard physical parameters, b=2, Td=50 K: The APEX Galactic Plane survey :  The APEX Galactic Plane survey Main goals: To have a complete census of high mass star formation in the Galaxy To derive the protostellar IMF down to below 1 Msol in a number of nearby regions Proposed area to observe at 870 mm: -80° < l < +20° ; | b | < 1° Northern part of the plane: complementarity with SCUBA-2 The APEX Galactic Plane survey :  The APEX Galactic Plane survey Sensitivity: one-s = 10 mJy 0.4 Msun detected at 5s at 1 kpc 30 Msun detected at 5s in the Gal. Center Some limited areas in a few southern star forming regions with higher sensitivity (well below 1 Msol) Total observing time: about 1000 hours The APEX Galactic Plane survey:  The APEX Galactic Plane survey Instrumentation: LABOCA (Large APEX BOlometer CAmera) = 295 bolometers for observing at 870 mm APEX beam at 870 mm: 18"= MSX pixels = Herschel at 250 mm The APEX Galactic Plane survey Possible extensions:  The APEX Galactic Plane survey Possible extensions Additional observations at shorter wavelengths: a 37- channel array operating at 350 m will be available soon complementary observations in selected regions Polarimetry at all wavelengths Additional observations at longer wavelengths: use of the UC Berkeley SZ camera (1.4 and 2 mm) as a backup project well-suited for poor weather conditions  dust emissivities (’s) Great complementarity with Herschel GP surveys Slide52:  Telescope “ready”: 11 / 2003 Holography 5 / 2004 1.2 mm Bolometer 5 / 2004 - first light: May 29 460/810 GHz Rx 6 / 2004 Holography 5 / 2005 Regular operation: 8? / 2005 LABOCA-1: 12? / 2005 ASZCa ? / late 2005 CHAMP+ ? / fall 2005 350 micron bolometer ? / 2006 LABOCA-2 (TES technology) ? APEX Timeline 15 m rms Cornell Caltech Atacama Telescope:  Cornell Caltech Atacama Telescope Joint project of Cornell and Caltech/JPL New telescope for submillimeter astronomy 25 m diameter – not confusion limited in reasonable exposure High aperture efficiency up to 200 µm wavelength High, dry, low latitude site – northern Chile (> 5000 m) Field of view (> 15′) for large format bolometer arrays 12 µm surface quality, closed loop active control Feasibility study underway Construction 2008 – 2012 CCAT Slides courtesy of S. Radford  Poster CCAT Design Concept:  CCAT Design Concept 25 m dia., 12 µm surf RC optics, 20′ FOV Active primary surface Panels: large, stiff, kinematic mounts Steel mirror truss Nasmyth foci Az: Hydrostatic bearings El: Rolling elem. bearings Calotte dome Slide56:   Gary Melnick’s talk Slide57:  Dome C – Concordia Station Altitude 3250 m South pole: 2300 m Dome A: > 4000 m Could build large single dish plus interferometer of arbitrary baseline length Thank You:  Thank You Bonus Material:  Bonus Material Slide60:  Lots of new entries for Glen Petitpas’: Dumb Or Overly Forced Astronomical Acronyms Site (or DOOFAAS) Slide61:  AC-coupling/DC-bias (old ) vs. DC-coupling vs. AC-bias (new) DC-bias (old) simpler to implement Amplifier have extra noise that rises with falling frequency (1/f). With a wobbler this is not a problem, because we have amplifiers with which 1/f noise only appears below the wobbler frequency (2Hz) Downside: is By wobbling, we do not modulate the total power at the input, therefore the total power is still affected by 1/f-noise. Block DC part and let only AC part through (capacitor between bolo and preamp input  throw away total power) AC-bias (LABOCA) get rid of 1/f noise need phase sensitive detection at the bias frequency  more complex to implement Big advantage: Retain total power  maps contain all the structure Other additional complexity: Need to compensate any change of voltage at the input of the amplifier (atmospheric variations) by an opposing voltage between scans AND keep track of that voltage.  Solved at SHARC II/CSO Slide62:  Solar system objects size scales <1“ (moons, KBOs) to ~1‘ (Jupiter) best done with ALMA (except for nearby comets) no array detector advantage Matthews/Senay/Jewitt (JCMT) Slide63:  3 mm region (70 – 116 GHz) in 500 MHz chunks 4000 – 5000 lines!!!! With ALMA it will be possible to observe that whole spectral range within 10 minutes to confusion limit Slide64:  To make any believable identification of a new species (e.g., glycine) in this jungle you need an interferometer. Show that many lines from candidate species all arise from the same position with the “correct” relative intensities. Usefulness of this approach was demonstrated by L. Snyder and collaborators using BIMA. Slide65:  Spectral line emission in Orion-KL Toward source I mainly SiO Sulphur-bearing species toward Hot Core and Compact Ridge Sulphur- and oxygen-bearing species toward IRc6 Imaging helps to identify lines Oxygen-bearing molecules weaker toward Hot Core and strong toward Compact Ridge Nitrogen-bearing molecules strong toward Hot Core  Henrik Beuther’s talk Confusing picture: Effects of chemistry and excitation Imaging helps! Slide66:  To do science with (3D) line surveys one needs very advanced data analysis tools: Automatic line identification and information extraction (fluxes, velocities) requires up-tp-date “living” molecular spectroscopy database LTE analysis  maps of N(X), Trot non-LTE analysis (LVG/Monte Carlo least sqares method; see Leurini et al. 2004 for CH3OH)  maps of n, Tkin, [X/H2] Fit dynamical models Above all: You need to use an interferometer Slide67:  K-band-Science (18 – 26 GHz) For temperature and column density determinations ideal: Ammonia (NH3) Multiple K-band lines (23.6 – 25 GHz) that can be done simultaneously and simultaneously with 22.2 GHz H2O maser line and simultaneously with 25 GHz series of CH3OH lines (maser and thermal) K-band RX array would be VERY interesting! Slide68:  Mapping speed (1 square degree) rms(1 sec) = 0.2 K at 90 GHz IRAM 30m 24” FWHM@90 GHz Positions to observe for a Nyquist-sampled map of 1 square degree 90000 Time needed for a map with an N pixel array 25/N hours Slide69:  Current and future SZ surveys: name type beam telescope clusters when arcmin m ACBAR Bolo 4 few ? Bolocam Bolo 151 1 10 10s ? SuZIE Bolo 1 10 ? 1997 BIMA HEMT few 2001 CBI HEMT 13 4 0.9 ? ? SZA HEMT 8 0.1 3.5 ? 2005? AMiBA HEMT 19 2 1.2 100s 2006 AMI HEMT 10 1 3.7 100s 2006 APEX Bolo 325 0.75 12 1,000s 2006 ACT Bolo 1000 1 6 1,000s 2007 Bolocam-2 Bolo 0.2 40 ? 2007? SPT Bolo 1000 1 8 20,000 2007 Planck Bolo 5 2 10,000 2008 Compilation: F. Bertoldi

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