Jason Glenn Gordon Stacey

Transcription

1 Jason Glenn Gordon Stacey

2 Need to put in a bit of background Science Spectrometers that exist now Move towards multi-object spectrometers

3 Herschel is detecting tens of thousands of submm galaxies Paul Goldsmith and Mike Seiffert have published a design for a Flexible Quasioptical Input System for a Submillimeter Multiobject Spectrometer (2009 PASP ) Jason, Jonas, and P. Maloney submitted a NASA APRA proposal to do a technology demonstration for a multiobject spectrometer using flexible waveguides and far-infrared KIDs that serves as a precursor for SOFIA and CCAT Z-Spec Cloverleaf results ZEUS detecting redshifted [CII] from a variety of systems ZEUS-2 nearing completion Array receivers are being proposed for big, single-dish telescope (e.g., GBT, LMT) and interferometers (e.g., CARMA) for point source and distributed source observations

4 The Antenna Galaxies Visible (HST) Near-Infrared(Spitzer) Submillimeter (CSO) The interstellar medium in galaxies obscures star formation and supermassive black hole formation, intercepting optical & UV radiation and reemitting it in the infrared and submillimeter. Glenn

5 For a realistic model of galaxy formation, we must understand the galaxies that give rise to the (enormous) Cosmic Far-Infrared Background Radiation COBE (1996): The Cosmic FIR background nearly equals the extragalactic optical/uv background dust-obscured galaxy (star) formation CCAT DUST STARLIGHT Glenn Lagache, Puget, & Dole 2005

6 Rest-frame Sub/Millimeter CCAT Rest-frame Far-Infrared: Redshifted into submillimeter for z z= z= z=3.0 Model Spectrum Glenn Sgr B2 Spectrum, ISO LWS, Goioechea et al. 2003

7 Detection rates of distance submillimeteremitting galaxies (A. Blain) Glenn CCAT 32x32 detector array 200 µm 350 µm 450 µm 620 µm 750 µm 850 µm

8 The galaxy images are stunning, but look at the backgrounds! Science Demonstration Phase data will be acquired in October & November, with a workshop and publications to follow early in spring Glenn The submm sky is rich and there will be much to do with CCAT: Herschel will resolve only ~10% of the submm background and redshifts will be scarce.

9 M74 is ~10 in diameter Glenn

10 Speed of follow-up & galaxy clustering Submillimeter galaxies in the vicinity of z = 2.38 Lyα clouds J (Galaxy protocluster?) Circles: probable detections (22) Squares: possible detections (10) 870 µm map from IRAM 30 m Lyα emitters Approximate F.O.V. requirement (minimum) for CCAT! QSOs Photometric redshifts indicate seven or more 5 20 x L solar galaxies with 2.0 < z < 2.8 spectroscopic redshifts are needed. ALMA primary beam size at 350 µm Glenn Beelen et al., astro-ph/

11 Why Do We Need Multi-Object Spectroscopic Capability? Sites of star formation are clustered Bolocam mm continuum Bally, Glenn, Aguirre, Drosback, Ginsburg, + UTexas & UBC NGC1333, Bolocam Enoch et al CCAT Goal FOV; 20 fibers Glenn

12 Assuming Identical atmospheric transmission (conservative for CCAT) Identical telescope surface RMSs (conservative for CCAT) Identical spectrometer sensitivities (very conservative for CCAT) Spectral resolution of R ~1,000 for line survey & redshift measurement With only one beam (i.e., one object, one fiber), CCAT do quick line surveys & redshift measurements with the same speed as ALMA With a handful of fibers & realistic sensitivities, CCAT would be >10x faster than ALMA in the 350 µm window SPEED SPEED Set : ALMATelescopes CCAT ALMA Glenn = 25m = 12m ALMATunings CCATBeams CCAT ALMA SPEED SPEED Solve forn N D D N N CCAT ALMA = = 1 CCATBeams = 10! 1!! N N = 50 CCATBeams ALMATelescopes ' % & D D CCAT ALMA $ 2 " N # ALMATunings CCAT will be capable of (and required for) spectroscopic follow-up of its own continuum survey catalogs

13 CO rotational ladder: Δν = 115 GHz/(1+z) Direct redshift indicator ladder constrains the physical conditions of the molecular ISM molecular gas mass, excitation [CII] line: Bright! times brighter than mid-j CO lines At z ~1 to 2 mid-j CO receivers 5 to 10 times more sensitive, but [CII] is still easier to detect (on CCAT) Indirect redshift indicator but not too bad since Next comparable brightness shorter wavelength lines are [OIII] (88 and 52 µm) very high z Next comparable brightness longer wavelength lines would be [NII] then check for [CII] or nearby mid-j CO optically distinguishable. Insights on strength of far-uv field, extent of starburst Best is a combination of the line tracers

14 First CO J = 7-6, 8-7, & 9-8 measurements Demonstrates redshift search technique Constrained molecular gas mass (2-50x10 9 M solar ) and pressure (nt>10 6 K cm -3 ) Conclude UV photons and X-rays heat the molecular gas Glenn

15 ZEUS grating spectrometer built to detect redshifted fine-structure line emission from distant galaxies First detection is: MIPS J1428, a hyper-luminous galaxy at z = discovered by Spitzer in Bootes deep field (Borys et al 2006) Subsequent observations show the FIR continuum emission has T d = 42.7 K and a total luminosity of L IR = 3.2 x L Hailey-Dunsheath et al near submission.

16 Lacks any trace of AGN activity likely a distant, luminous analogue of local IRAS selected galaxies, or distant submm selected galaxies Spectrum and far-ir radio flux ratio consistent with a super starburst galaxy Source is likely lensed by a foreground (z = elliptical, but magnification < 10) Strong CO line emission: M ~ M Iono et al

17 [CII] line detected with ZEUS on the CSO with an apparent luminosity, L [CII] ~ L about the far-ir continuum. [CII] line to far-ir continuum ratio in of itself constrains the far-uv field ~ 2000 Together with CO line trace the physical parameters of the gas: n ~ 4000 cm -3 Far-UV fields combined with observed far-ir tells us that we have a galaxy-wide starburst with a characteristic size ~ 6 kpc diameter Scaling from M82, one would arrive at a similar conclusion: MIPS J is undergoing a 4-12 kpc wide starburst

18 Trend towards smaller [CII]/far-IR ratio going away SMGs look like global starbursts High z systems dominated by quasars Good news for [CII] surveys of distance galaxies!

19 Z-Spec ZEUS

20

21 Glenn

22 Glenn

23 Glenn

24 Glenn

25

26 Desire R λ Δλ ~ 1000 optimized for detection of extragalactic lines Operate near diffraction limit: Maximizes sensitivity to point sources Minimizes grating size for a given R Long slit desirable Spatial multiplexing Correlated noise removal for point sources Choose to operate in n = 3, 4, & 5 orders which covers the 610, 450 and 350 µm windows respectively Wavelength (µm) ZEUS Windows ZEUS spectral coverage superposed on Mauna Kea windows on an excellent night

27 Grating BP Filter Wheel M4 Detector Array LP Filter 2 M6 M2 4 He Cold Finger M5: Primary Dual stage 3 He refrigerator M1 M3 LP Filter 1 Scatter Filter Entrance Beam f/12 4 He cryostat There is a series of a scatter, quartz, 2 long λ pass, and a bandpass filter in series to achieve dark performance (P. Ade) Total optical efficiency: ~ 30%, or 24% including bolometer DQE

28 Echelle LWP Filter Detector Cold Finger Cold Head 3 He refrigerator Entrance to Helium section Detector sensitivity requires a dual stage 3 He refrigerator (T ~ 210 mk) Spectral tuning is easy turn the grating drive chain Switching telluric windows is easy turn a (milli K) filter wheel Optics are sized to accommodate up to a pixel array 12 spatial samples 64 spectral elements (> 6% BW) Sampled at 1 res. el./pixel to maximize spectral coverage Interior of ZEUS with some baffles removed. The collimating mirror is hidden behind the middle wall baffles.

29 ZEUS-1 has a 1 32 pixel thermister sensed array from GSFC (SHARC-2 prototype) Building ZEUS-2 with TES sensed NIST Arrays µm , 450 µm , 800 µm Resonantly tuned arrays better sensitivity SHARC-2 CSO GSFC

30 Upgrading to (3) NIST 2-d TES bolometer arrays Backshort tuned 5 lines in 4 bands simultaneously 215 µm (1.5 THz) 350 µm (850 GHz) 450 µm (650 GHz) 625 µm (475 GHz) Imaging capability (9-10 beams)

31 M51 - CO(1-0): BIMA Song (Helfer et al. 2003) 12 CO(7-6) 13 CO(6-5) [CI] 3 P 2-3 P 1 [NII] 3 P 1-3 P 0 [CI] 3 P 1-3 P 0 Astrophysics [CI] line ratio: Strong constraints on T 13 CO(6-5) line: Strong constraints on CO opacity [NII] line: Cooling of ionized gas, and fraction of [CII] from ionized media Mapping Advantages Spatial registration perfect Corrections for telluric transmission coupled Expected SNR for the five lines comparable

32 ZEUS detects [CII] from z ~ 1.1 to 2.1 (350 and 450 µm windows) Covers the peak in the star-formation rate per co-moving volume ZEUS-2 expands [CII] coverage to z ~ 0.25 to 3: Straddles the peak tracing the star formation history of the Universe from 11 Gyr ago to the current epoch Other lines accessible as well: ZEUS [CII] Windows Blain et al. 2002, Phys. Rep., 369, 111 [OI] 63 µm: PDRs UV field strength [OIII] 88 µm: ZEUS-1 ZEUS-2 UV field hardness [NII] 122 & 205 µm: n e tracer, [CII] from HII regions

33 With a Milky Way ratio (L [CII] /L far-ir ~ 0.3%, the [CII] line is detectable at redshifts in excess of 5 for L far-ir > L ULIGS typically have 5 times weaker line ratio, so that a L ULIRG is readily detectable! Note that for the Milky Way ratio, the line to continuum ratio (optimally resolved line) is ~ 5:1. An optimized (R ~ 1000 spectro-meter is 10 times less sensitive than an optimized (R ~ 10) photometer Therefore, the line is detected at only 2 times worse SNR than the continuum in the same integration time. L(far-IR) [CII] Limits in terms of L far-ir ULIRGs 1.0E E+11 Milky Way 1.0E E Redshift 5 σ in 4 hours 33

34 ZEUS-2 naturally lends itself to a multi-object nature if we can pipe the light in. If configured in one band (say 350/450 µm), then the usable FoV is ~ 20 beams To avoid source confusion, could configure with 10 feeds Z-Spec s modularity also lends itself well to multi-beam configurations through stacking of the planar waveguides.

35 Mirror MOS Useful for observations of sources which have a low density on the sky Patrol regions over the focal plane assigned to each receiver Low transmission loss with only four reflections Glenn

36 FIRMOS: Far-InfraRed Multi-Object Spectrometer technology development for SOFIA and CCAT Proposal submitted to NASA APRA March 2009 Goal: Demonstrate good throughput, spectral resolution, and sensitivity with a system with a system combining a few flexible waveguides (fibers), a diffraction grating, and some detectors Fibers : Hollow, interior-metallized polycarbonate tubes Detectors: far-infrared detectors like the ATACamera detectors Diffraction grating: Z-Spec-like parallel-plate, 1 st -order, Rowland grating Demonstration: µm from the CSO What follows: If successful, a µm MOS for SOFIA or a submm system for CCAT with 1 or 2 dozen fibers Glenn

37 Derive spectrometer pointing and tracking requirements for CCAT Do we want/need chopping? Continue technology development for MOSs: Mirrors, flexible waveguides, detectors The source densities and optimum field-of-view / number of objects will be updated after the Herschel results are release in the spring Heterodyne array receiver technology for spectral line mapping is proceeding in various groups Glenn

38 Glenn

39 There are significant scientific problems that will only be solved with CCAT in conjunction with other telescopes -CCAT must be considered not only in its complementarity to ALMA, but also JWST, Herschel, SOFIA, TMT et al., GBT. -CCAT is ideally suited to some outstanding questions, such as: How do molecular clouds evolve from the diffuse interstellar medium to dense cores? Glenn

40 How is CCAT complementary to ALMA? -With ~50 heterodyne receiver elements or ~1 beam in a broad band spectrometer for the 850 GHz window, CCATs spectroscopic speed will match ALMA -CCAT will be superior in the 850 GHz atmospheric window and the best (only consistent) site for µm observation -ALMA has a serious zero-spacing problem that the ACA won t solve that CCAT could address CCAT will be required for its own spectroscopic follow-up: -CCATs imaging source catalogs will be enormous -ALMA will be heavily oversubscribed Glenn

41 Receiver technology is extant for prototype first-light CCAT instruments and imminent for 2nd-generation instrumentation Instrumentation -Heterodyne array receivers will be required for mapping of molecular clouds and nearby galaxies -MOS are well suited for extragalactic point sources Instrument development priorities and planning? Toward a White Paper for the Decadal Survey? Glenn