G. J. Stacey

University of Lethbridge, Lethbridge, Alberta, Canada

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Publications (219)317.56 Total impact

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    ABSTRACT: We report the first detection of a mid-J isotopic CO line from an external galaxy. We detected the 13CO (6-5) line from the starburst nucleus of NGC 253. The line is suprisingly bright with an integrated intensity 7% of the 12CO (6-5) line, indicating optical depth in the 12CO line. Our LVG modeling shows that a single warm (T ~ 120 K), dense (n ~ 104 cm-3) component emits most of the 12CO and 13CO line emission from J = 2-1 through J = 7-6. The CO(1-0) line comes from an additional lower excitation envelope. About 60% of the total molecular gas mass within 70 pc of the nucleus is in the warm, dense component. We show that stellar far-UV photons or X-ray photons from a nuclear source are unlikely to be the primary sources of the gas heating. The most likely sources of heat are cosmic rays from the nuclear starburst or microturbulence within molecular clouds.
    EAS Publications Series 01/2008; 31:151-154.
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    ABSTRACT: We report the detection of the 158 mum [CII] line from the LIR ˜ 1014 L&sun; galaxy FSC 10026+4949 at z = 1.12. This is the first detection of [CII] from the z = 1-3 epoch of enhanced starformation. The L[CII]/LFIR ratio is 1.3 × 10-3, larger than the ratio typically seen in local ULIRGs, but similar to that measured in normal and starburst galaxies. This high ratio implies that the UV fields powering the far-infrared emission are of only modest intensity, and that FSC 10026+4949 may be undergoing a galaxy-wide starburst.
    EAS Publications Series 01/2008; 31:159-162.
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    ABSTRACT: We report the detection of 13CO J=6-->5 emission from the nucleus of the starburst galaxy NGC 253 with the redshift (z) and Early Universe Spectrometer (ZEUS), a new submillimeter grating spectrometer. This is the first extragalactic detection of the 13CO J=6-->5 transition, which traces warm, dense molecular gas. We employ a multiline LVG analysis and find ~35%-60% of the molecular interstellar medium is both warm (T~110 K) and dense (nH2~104 cm-3). We analyze the potential heat sources and conclude that ultraviolet and X-ray photons are unlikely to be energetically important. Instead, the molecular gas is most likely heated by an elevated density of cosmic rays or by the decay of supersonic turbulence through shocks. If the cosmic rays and turbulence are created by stellar feedback within the starburst, then our analysis suggests the starburst may be self-limiting.
    The Astrophysical Journal 01/2008; 689. · 6.73 Impact Factor
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    ABSTRACT: The fine structure line of [CI] at 370 μm, and the CO (7→6) rotational line at 371 μm are important coolants which can be used to probe the temperature and density of the warm gas component in regions of enhanced star formation. These lines can be used to provide key constrains on the physical properties of the warm molecular gas component and to deduce the excitation mechanism that heats the molecular gas. We have used the Cornell submillimeter spectrometer, SPIFI, on the JCMT to map the [CI] and CO (7→6) line emission from the nuclear regions of the nearby galaxies NGC 253 and M82, and from the overlap region of NGC4038/9. In both NGC 253 and NGC 4038/9 the [CI] emission appears fairly constant, while the CO (7→6) emission peaks at the nucleus and the most active star-forming region, respectively. The observations of NGC 253 suggest that the majority of the nuclear molecular gas is most likely heated by cosmic rays. The spatial distribution of the line emission in the overlap region of NGC 4038/9 is suggestive of a PDR, with a decrease in density from the most active region to the outside. In contrast, in M82 both the CO (7→6) and [CI] line intensities vary over the mapped region, with the line ratios remaining fairly constant. This suggests a change in the beam filling factor of PDRs with a higher PDR number density in the most active regions.
    12/2007: pages 225-230;
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    ABSTRACT: We discuss optical associations, spectral energy distributions (SEDs), and photometric redshifts for Spitzer Wide-Area Infrared Extragalactic (SWIRE) Survey sources in the European Large-Area ISO Survey (ELAIS) N1 area and the Lockman Validation Field (VF). The band-merged Infrared Array Camera (IRAC) (3.6, 4.5, 5.8, and 8.0 mum) and Multiband Imaging Photometer for Spitzer (24, 70, and 160 mum) data have been associated with optical UgriZ data from the Isaac Newton Telescope Wide Field Survey in ELAIS N1 and with our own optical Ugri data in Lockman-VF. Criteria for eliminating spurious infrared sources and for carrying out star-quasar-galaxy separation are discussed, and statistics of the identification rate are given. Thirty-two percent of sources in the ELAIS N1 field are found to be optically blank (to r=23.5) and 16% in Lockman-VF (to r=25). The SEDs of selected ELAIS sources in N1 detected by SWIRE, most with spectroscopic redshifts, are modeled in terms of a simple set of galaxy and quasar templates in the optical and near-infrared (NIR), and with a set of dust emission templates (cirrus, M82 starburst, Arp 220 starburst, and active galactic nucleus [AGN] dust torus) in the mid-infrared. The optical data, together with the IRAC 3.6 and 4.5 mum data, have been used to determine photometric redshifts. For galaxies with known spectroscopic redshifts, there is a notable improvement in the photometric redshift when the IRAC data are used, with a reduction in the rms scatter from 10% in (1+z) to 7%. Although further spectroscopic data are needed to confirm this result, the prospect of determining good photometric redshifts for much of the SWIRE survey, expected to yield over 2 million extragalactic objects, is excellent. Some modifications to the optical templates were required in the previously uninvestigated wavelength region 2-5 mum. The photometric redshifts are used to derive the 3.6 and 24 mum redshift distribution and to compare this with the predictions of models. For those sources with a clear mid-infrared excess, relative to the galaxy starlight model used for the optical and NIR, the mid- and far-infrared data are modeled in terms of the same dust emission templates (cirrus, M82, Arp 220, and AGN dust torus). The proportions found of each template type are cirrus, 31%; M82, 29%; Arp 220, 10%; and AGN dust tori, 29%. The distribution of the different infrared SED types in the LIR/Lopt versus LIR plane, where LIR and Lopt are the infrared and optical bolometric luminosities, respectively, is discussed. There is an interesting population of luminous cool cirrus galaxies with LIR>Lopt, implying a substantial dust optical depth. Galaxies with Arp 220-like SEDs, of which there are a surprising preponderance compared with preexisting source count models, tend to have high ratios of infrared to optical bolometric luminosity, consistent with having very high extinction. There is also a high proportion of galaxies whose mid-infrared SEDs are fitted by an AGN dust torus template (29%). Of these only 8% of these are type 1 AGNs according to the optical-NIR template fitting, whereas 25% are fitted with galaxy templates in the optical-NIR and have LIR>Lopt and so have to be type 2 AGN. The remainder have LIR<Lopt and so can be Seyfert galaxies, in which the optical AGN fails to be detected against the light of the host galaxy. The implied dust covering factor, >=75%, is much higher than that inferred for bright optically selected quasars.
    The Astronomical Journal 12/2007; · 4.97 Impact Factor
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    ABSTRACT: We present mid-infrared maps and preliminary analysis for 61 galaxies observed with the ISOCAM instrument aboard the Infrared Space Observatory. Many of the general features of galaxies observed at optical wavelengths—spiral arms, disks, rings, and bright knots of emission—are also seen in the mid-infrared, except the prominent optical bulges are absent at 6.75 and 15 μm. In addition, the maps are quite similar at 6.75 and 15 μm, except for a few cases where a central starburst leads to lower Iν(6.75 μm)/Iν(15 μm) ratios in the inner region. We also present infrared flux densities and mid-infrared sizes for these galaxies. The mid-infrared color Iν(6.75 μm)/Iν(15 μm) shows a distinct trend with the far-infrared color Iν(60 μm)/Iν(100 μm). The quiescent galaxies in our sample [Iν(60 μm)/Iν(100 μm) 0.6] show Iν(6.75 μm)/Iν(15 μm) near unity, whereas this ratio drops significantly for galaxies with higher global heating intensity levels. Azimuthally averaged surface brightness profiles indicate the extent to which the mid-infrared flux is centrally concentrated, and provide information on the radial dependence of mid-infrared colors. The galaxies are mostly well resolved in these maps: almost half of them have <10% of their flux in the central resolution element. A comparison of optical and mid-infrared isophotal profiles indicates that the flux at 4400 Å near the optical outskirts of the galaxies is approximately 8 (7) times that at 6.75 μm (15 μm), comparable to observations of the diffuse quiescent regions of the Milky Way.
    The Astronomical Journal 12/2007; 120(2):583. · 4.97 Impact Factor
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    ABSTRACT: We present the analysis of Infrared Space Observatory long-wavelength spectrometer (LWS) observations of the two nearby late-type galaxies NGC 1313 and NGC 6946. Both galaxies have been fully mapped in the [C II] far-infrared fine-structure line at 158 μm, and some regions have been observed also in the [O I] 63 μm and [N II] 122 μm lines. We use these observations to derive the physical properties of the atomic interstellar medium, to establish how they relate to other interstellar medium components (gas and dust), and to establish how they vary with different galaxy components such as nucleus, spiral arms, and disk. The [C II] line is the main cooling line of the atomic medium. In NGC 6946 and NGC 1313, its emission represents 0.8% of the infrared emission. Moreover, the [C II] emission can be spatially associated with three components: the nucleus, the star-forming regions in spiral arms, and the diffuse galaxy disk. This last component contributes 40% in NGC 6946 and ~30% in NGC 1313 to the total emission. We apply the photodissociation region (PDR) model by Kaufman et al. to derive PDR physical parameters responsible for the neutral atomic gas emission (G0, n, and Ts). The results do not significantly differ from what Malhotra et al. recently found by modeling the integrated emission of a sample of 60 normal galaxies. This suggests that the emission in each region under the LWS beam in NGC 6946 and NGC 1313 (corresponding to a linear size of ~1.5 kpc) is likely to arise from a mixture of components similar to the mixture producing the integrated emission of normal galaxies. However, some regions in NGC 6946 have a G0/n ratio ~2–3 times smaller than the mean value found for the normal galaxy sample (1.3), suggesting that the beam-averaged contribution of a less active component in these regions is higher than its contribution in the integrated emission of normal galaxies or, conversely, that the bulk of the integrated emission of the normal galaxies is dominated by a few active regions probably located in their nuclei. CO(1–0) and [C II] in NGC 6946 are well correlated, and the mean [C II]/CO ratio agrees with the mean integrated ratios of the normal galaxies sample. This value (~500) is a factor of ~2 less than the mean ratio found for a sample of normal galaxies observed with the Kupier Airborne Observatory (KAO) by Stacey et al. This difference is probably due to the fact that the KAO beam (55'') is smaller than the LWS beam (75''), such that the Stacey et al. KAO observations are likely to be more biased toward the nucleus of the galaxies and therefore toward more active regions. In NGC 1313 only four LWS regions have been observed in CO(1–0), and three of them were detected. The [C II]/CO(1–0) seems to systematically increase from the northeast to the south, along the S-shaped spiral arm, indicating that the interstellar medium conditions in NGC 1313 are much more inhomogeneous than the conditions in NGC 6946. H I and [C II] in NGC 6946 are completely uncorrelated, probably because they arise from different gas components: [C II] arises principally in dense and warm PDR and H I from diffuse (n 3 × 103 cm-3) gas. On the other hand, in NGC 1313 we successfully detect two distinct gas components: a cirrus-like component, for which H I and [C II] are weakly correlated as observed in our Galaxy, and a component associated with dense PDRs completely uncorrelated from H I as observed in NGC 6946. Finally, we find that the H I residing in dense gas surrounding the star-forming regions and presumably recently photodissociated constitutes a few percent of the total H I. In turn, this dense gas component produces most of the [C II] emission emitted by the atomic neutral medium, even if its contribution is lower in NGC 1313 than in NGC 6946. On the other hand, the [C II] emission arising from ionized gas is higher in NGC 1313 than in NGC 6946.
    The Astronomical Journal 12/2007; 124(2):751. · 4.97 Impact Factor
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    ABSTRACT: The far-infrared and submillimeter regimes harbor significant numbers of strong lines useful as diagnostics of processes in the interstellar medium, regions of intense star formation, and AGN activity. Covering a decade or more in wavelength, many of them are emitted or redshifted to wavelengths where they are obscured by atmospheric absorption, and so airborne and space-based instruments must be used. Capable, sensitive detector arrays are needed for this; we have been developing such arrays based on multiplexed superconducting bolometers. At the present level of maturity, we have fielded a submillimeter spectrometer containing around ten detectors of the requisite sensitivity. In the coming months, new instruments will demonstrate up to of order 100 bolometers (e.g., 8× 16). We are working to implement over a thousand pixels in a single detector package. One application for such large arrays is the 100 μ m-655 μ m spectrometer SAFIRE on SOFIA. Future directions will be for space-based observatories such as SAFIR.
    09/2007; 375:217.
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    ABSTRACT: We propose to obtain deep IRS spectra of the outer disk of the nearby edge on spiral galaxy NGC 891. Our primary goal is to investigate the physical state, mass, and heating processes in the molecular ISM through investigations of four pure rotational lines of H2. Pioneering work in the S(0) and S(1) lines with ISO indicate large quantities of warm (T ~ 120 K) molecular clouds along the disk of the galaxy ? fully half of the cold H2 component traced in CO. Furthermore, the ISO results suggest vast quantities of cool (T 12 kpc) for cool molecular gas by deep integrations in the S(1) and S(0) lines. Finally, we plan a sparse map of most of the disk to detect the S(3) line using the Short-Lo spectrometer. The S(0), S(2), and S(1) and S(3) transitions constrain the excitation of para and ortho H2 respectively, and together yield the o/p ratio. The four lines will therefore solidly establish the mass of warm and cool molecular gas in NGC 891. Are there massive quantities of cool gas in the outer disks of galaxies?
    Spitzer Proposal. 05/2007;
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    ABSTRACT: We have obtained large scale, 1' resolution maps of the edge-on spiral galaxy NGC 891 in the 158 micron [CII] and CO(1 - 0) lines. The [CII] distribution largely follows the optical image, but is significantly asymmetric - there is a pronounced ridge of emission to the north. The CO(1 - 0) and 2.8 cm radio continuum are similarly asymmetric suggesting that the [CII] emission arises from both the UV exposed surfaces of giant molecular clouds and from the diffuse ionized medium. For low density media, we estimate 25% of the observed [CII] emission arises from ionized gas clouds. The HI 21 cm line emission bears little resemblance to the other tracers, along the major axis. Assuming "standard" atomic cloud parameters, only 15% of the observed [CII] intensity along the plane comes from the atomic medium. The remainder (60%) of the [CII] emission is associated with dense photodissociation regions (PDRs) on the surfaces of molecular clouds. The [CII]/CO(1 - 0) line intensity ratio for these regions is similar to Galactic molecular clouds, providing an important link between the molecular clouds in NGC 891 and the Milky Way. For the outer regions (r > 4 kpc) of NGC 891, most of the [CII] emission arises from atomic clouds with Galactic parameters (T 100 K, n 30 cm-3). The enhanced [CII] to FIR continuum ratio in these outer regions is a reflection of the increased efficiency for photoelectic heating in low UV field environments. Integrated over the galaxy about 25% of the observed [CII] emission arises from atomic clouds. The [CII] emission may be marginally resolved in the z direction with our 55" beam - indicating a scale height larger than that of CO. This extraplanar [CII] may be associated with the "filaments" observed in the optical recombination lines.
    04/2007: pages 90-91;
  • Thomas Nikola, Gordon J. Stacey, Terry Herter
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    ABSTRACT: We present a concept for a far-IR integral field spectrograph for SOFIA, the Cornell Mapping Spectrometer (CMS). CMS takes advantage of the next generation of large bolometer arrays to deliver moderate resolution spectroscopy in the wavelength range between 40 mum and 220 mum over a large field of view. Two separate wavelength channels with each employing six SCUBA-2-like bolometer arrays will provide 64 element spectra over a 10 × 12 spatial pixel footprint. By matching the pixel size to the beam size the field of view obtained is 190" × 160" at the important [CII] line in the long-lambda channel and 77" × 64" at the [OI] line in the short-lambda channel. The sliced image is fed into an R2 echelle spectrometer of modest resolving power (R ≈ 2000). The grating will operate in 4th order at 158 mum in the long-lambda channel and 4th order at 63 mum in the short-lambda channel. This results in nearly matching orders for other important fine-structure lines of [NII] and [OIII]. Filterwheels are placed right in front of the detector arrays to separate the orders. By subdividing the detector assemblies and appropriately placing the 3 × 1 detector sub-assemblies it is possible to observe four fine-structure lines simultaneously. CMS combines the advantages of a FIFI-LS design (instantaneous spatial and spectral coverage) with the sensitivity advantage of bolometers over photo-conductors. This will make CMS the instrument of choice for deep spectroscopic integrations of extended regions in galaxies.
    Proc SPIE 01/2007;
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    ABSTRACT: We report results of a recently-completed pre-formulation phase study of SPIRIT, a candidate NASA Origins Probe mission. SPIRIT is a spatial and spectral interferometer with an operating wavelength range 25–400 μm. SPIRIT will provide sub-arcsecond resolution images and spectra with resolution R = 3000 in a 1′ field of view to accomplish three primary scientific objectives: (1) learn how planetary systems form from protostellar disks, and how they acquire their inhomogeneous composition; (2) characterize the family of extrasolar planetary systems by imaging the structure in debris disks to understand how and where planets of different types form; and (3) learn how high-redshift galaxies formed and merged to form the present-day population of galaxies. Observations with SPIRIT will be complementary to those of the James Webb Space Telescope and the ground-based Atacama Large Millimeter Array. All three observatories could be operational contemporaneously.
    Advances in Space Research. 01/2007;
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    ABSTRACT: Understanding galaxy formation is at the foundation of extragalactic astronomy. Galaxies are thought to be assembled via mergers of small dwarf-like systems at high redshift. One of the best ways of providing observational constraints to the models is through a better understanding of local examples of these "building blocks", star forming dwarf galaxies. We have exploited the SWIRE legacy database to perform an unbiased search for extreme star forming PAH-rich dwarf galaxies. We wish to observe a complete and flux-limited 8 um selected sample of 27 PAH-rich dwarf galaxies in the ELAIS N1 field with the Infrared Spectrograph. This proposal is part of a much larger study of the PAH-rich dwarf galaxy population. However, the Spitzer observations are critical for our project as this is a mid-infrared selected sample and we need to compare the mid-infrared properties with Spitzer surveys of known galaxy type. Only Spitzer enables us to measure the PAH features; directly observe the low-J rotational molecular hydrogen lines; and the fine structure lines in a practically extinction-free wavelength range. These observations will characterize the physical properties of the star-forming regions, e.g., star formation rate, excitation, electron density, warm molecular gas mass. Please note that this is a COMPLETE SURVEY OF 27 PAH-RICH DWARVES. The SPITZER TIME request is SPLIT between this GTO proposal (SJH_PDGT), which has my total GTO time allocation of 6.6 hrs for 4 sources AND a GO proposal (SJH_PDGO) to observe the remaining 23 SOURCES in 37.9 hrs.
    Spitzer Proposal. 05/2006;
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    ABSTRACT: We propose to investigate the nature of a sample of high luminosity infrared bright galaxies in the redshift range of 0.6 to 3 through complete IRS high resolution spectroscopy. Our sample focuses on systems that we will observe in March 2006 in their 158 micron [CII] line emission using Cornell's submm grating spectrometer, ZEUS on the CSO. The combined [CII] and Spitzer IRS spectroscopy will comprise the thesis work of Cornell student Steven Hailey-Dunsheath. The combined data sets will (1) Determine the hardness of the ambient interstellar radiation fields thereby tracing the most massive stars on the main sequence, or revealing the presence of an AGN. (2) Determine the total ionizing flux from stars, hence the relative importance of starformation to accretion in creating the IR luminosity of these sources. (3) Determine the strength of the ambient far-UV radiation fields, hence the physical sizes of the starforming regions. The sources proposed here are among the most distant, and most luminous sources known in the Universe. As such, they are heavily studied by many research groups. We propose deep IRS high resolution spectroscopy for these sources, for which we have built a scientific case coupled to research going on in our group at Cornell. It is clear that the spectra that we obtain will be invaluable for many other science programs including future programs involving Herschel, and JWST. We therefore welcome and encourage collaborations.
    Spitzer Proposal. 05/2006;
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    ABSTRACT: We present a first cut instrument design package for the proposed 25 meter Cornell-Caltech Atacama Telescope (CCAT). The primary science for CCAT can be achieved through wide field photometric imaging in the short submillimeter through millimeter (200 mum to 2 mm) telluric windows. We present strawman designs for two cameras: a 32,000 pixel short submillimeter (200 to 650 mum) camera using transition edge sensed bare bolometer arrays that Nyquist samples (@ 350 mum) a 5'×5' field of view (FoV), and a 45,000 pixel long wavelength camera (850 mum to 2 mm) that uses slot dipole antennae coupled bolometer arrays with wavelength dependent sampling that covers up to a 20' square FoV. These are our first light instruments. We also anticipate "borrowed" instruments such as direct detection and heterodyne detection spectrometers will be available at, or nearly at first light.
    Proc SPIE 01/2006; 6275.
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    ABSTRACT: We present an 11 arcsec resolution map of the central two parsecs of the Galaxy in the CO J =7->6 rotational transition. The CO emission shows rotation about Sgr A*, but also evidence for non-circular turbulent motion and a clumpy morphology. We combine our dataset with available CO measurements to model the physical conditions in the disk. We find that the molecular gas in the region is both warm and dense, with T~200-300 K, n_H2~50,000-70,000 cm^-3. The mass of warm molecular gas we measure in the central two parsecs is at least 2000 M_solar, about 20 times the UV-excited atomic gas mass, ruling out an UV heating scenario for the molecular material. We compare the available spectral tracers with theoretical models and conclude that molecular gas is heated with magneto-hydrodynamic shocks with v~10-20 kms and B~0.3-0.5 mG. Using the conditions derived with the CO analysis, we include the other important coolants--neutral oxygen and molecular hydrogen--to estimate the total cooling budget of the molecular material. We derive a mass to luminosity ratio of 2-3 M_solar/ L_solar, which is consistent with the total power dissipated via turbulent decay in 0.1 pc cells with v_rms~15 kms. These size and velocity scales are comparable to the observed clumping scale and the velocity dispersion. At this rate, the material near Sgr A* its dissipating its orbital energy on an orbital timescale, and cannot last for more than a few orbits. Our conclusions support a scenario in which the features near Sgr A* such as the CND and northern arm are generated by infalling clouds with low specific angular momentum. Comment: 31 pages, including 5 figures, accepted for publication in ApJ
    The Astrophysical Journal 01/2005; · 6.73 Impact Factor
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    ABSTRACT: The redshift (Z) and of Early Universe Spectrometer (ZEUS) is a long slit echelle grating spectrometer that we are constructing for use in the submillimeter (350mum, 450mum, and 610mum) windows on the James Clerk Maxwell Telescope (JCMT). ZEUS has a resolving power of R≡lambda/DeltaLambda~1000, optimized for detecting broad, faint lines from extragalactic sources. The detector is a 16×32 pixel array of pop-up bolometers equipped with superconducting transition edge sensors linked into a SQUID multiplexed readout. This array should provide the requisite sensitivity at ~300mK, a temperature easily achieved using a two stage 3He refrigerator. ZEUS is optimized to quickly obtain spectra of point sources over very broad bands in the submillimeter windows. In the 350mum window, ZEUS will provide an instantaneous 27 resolution element spectrum, for each of 16 spatial elements on the sky. The roughly 10% bandwidth 350mum window can therefore be covered with just four settings of the grating. Each pixel is mapped into 5" on the sky (roughly 1•lambda/D at 350 mum), so that the field of view is 5"×80". At 610mum, the slit is opened to 12" (2.4 pixels) resulting in a resolving power of around 500. ZEUS can quickly change wavelength or telluric window, adapting well to the demanding weather conditions in the short submillimeter windows. To minimize the effects of stray background radiation, two cold cut-on filters are used, together with 300mK band pass filters mounted on a filter wheel. This filter train fully sorts the echelle grating order, blocking unwanted radiation, but with high submillimeter band transmission. The expected point source sensitivities for 370mum, 444mum, and 610mum are 2.7×1017 W m-2Hz-1/2, 1.2×10-17 W m-2Hz-1/2, and 1.6×10-17W m-2Hz-1/2, respectively. Our primary scientific objectives are to (1) Investigate Ultraluminous Infrared Galaxies (ULIGs) via their (CI) and mid-J CO line emission-what are the origins of their tremendous infrared (IR) luminosities? Why are some ULIGs weak in the 158 mum (CII) line? (2) Probe star formation in the early Universe using highly redshifted far-IR fine-structure line emission-especially that of the 158 mum (CII) line. How strong are starbursts in the early Universe? and (3) Provide redshifts for all 850 mum SCUBA sources, providing source distance, luminosity, and number counts as a function of z. What is the evolutionary history of starformation in the early Universe?
    Proc SPIE 12/2004;
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    ABSTRACT: We have been developing an architecture for producing large format, two-dimensional arrays of close-packed bolometers, which will enable far-infrared to millimeter wavelength (lambda=100μm-2mm) cameras and spectrometers to obtain images and spectra orders of magnitude faster than present instruments. The low backgrounds achieved in these instruments require very sensitive detectors with NEPs ranging from 10-17 to 10-19 W/(Hz-1/2). Superconducting transition edge sensor bolometers can be close-packed using the Pop-Up Detector (PUD) format, and SQUID multiplexers operating at the detector base temperature can be intimately coupled to them. The array unit cell is 8x32 pixels, using 32-element detector and multiplexer components. We have fabricated an engineering model array with this technology featuring a very compact, modular approach for large format arrays. We report on the production of the 32-element components for the arrays. Planned instruments using this array architecture include the Submillimeter and Far-InfraRed Experiment (SAFIRE) on the SOFIA airborne observatory, the South Pole Imaging Fabry-Perot Interferometer (SPIFI) for the AST/RO observatory, the Millimeter Bolometer Camera for the Atacama Cosmology Telescope (MBC/ACT), and the Redshift "Z" Early Universe Spectrometer (ZEUS).© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
    10/2004;
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    ABSTRACT: Cornell and Caltech are undertaking a two year conceptual design study for a 25-m class sub-mm telescope. The nominal location for this facility will be the high Atacama Desert of Northern Chile. The baseline design is a segmented mirror telescope optimized for operation at wavelengths longer than 200 microns to take advantage of a low precipitable water vapor at the site. We discuss science drivers and their implications for telescope design and technical requirements, and planned technical study areas.
    Proc SPIE 10/2004;
  • Proc SPIE 09/2004;

Publication Stats

2k Citations
317.56 Total Impact Points

Institutions

  • 2014
    • University of Lethbridge
      Lethbridge, Alberta, Canada
  • 1992–2012
    • Cornell University
      • Department of Astronomy
      Ithaca, New York, United States
  • 1991–2009
    • University of California, Berkeley
      • Department of Physics
      Berkeley, CA, United States
  • 2005
    • California Institute of Technology
      Pasadena, California, United States