The EDGE Project - University of...

The EDGE Project

Stephan S. Meyera, Edward S. Chengb, David A. Cottinghamc,Dale J. Fixsend, Lloyd Knoxe, Robert Silverbergb, Peter Timbief and Grant Wilsong

aUniversity of Chicago, EFI, Center for Cosmological Physics, Chicago, IL, USAbNASA/Goddard Space Flight Center, Greenbelt, MD, USA

cNASA/GSFC, GST, Greenbelt, MD, USAdNASA/GSFC, SSAI, Greenbelt, MD, USA

eUniversity of California, Dept. of Physics, Davis, CA, USAfUniversity of Wisconsin, Dept. of Physics, Madison, WI, USA

gUniversity of Massachusetts, Dept, of Astronomy, Amherst, MA, USA

ABSTRACTEDGE is a Long Duration Balloon (LDB) borne instrument designed to measure the large-scale anisotropy of the CosmicInfrared Background (CIB). The goal is to use this signal as a new observational tool to measure the character of the spa-tial distribution of galaxies at the largest spatial scales. With a 6′ beam mapping more than 400 square degrees of sky at8 frequency bands between 250GHz and 1.5 THz the experiment can determine the variation of galaxy density on spatialscales ranging from> 200 h−1Mpc, where dark matter variations are determined directly from Cosmic Microwave Back-ground Radiation (CMBR) anisotropy, to < 5 h−1Mpc where the distribution of dark matter and galaxies is determinedfrom galaxy redshift surveys and the underlying dynamics of structure growth is non-linear. The instrument consists of a1-meter class off-axis telescope and a Frequency Selective Bolometer (FSB) array radiometer. The FSB design providesthe compact, multi-chromatic, high sensitivity focal plane needed for this measurement.

Keywords: Cosmology, Cosmic Infrared Background, Frequency Selective Bolometers

1. SCIENCE GOALEDGE will measure the galaxy distribution on the largest spatial scales through a new observational tool, the anisotropy ofthe Cosmic Infrared Background (CIB). CIB variations, when observed with 6′ resolution as surface brightness changes,probe the distribution of galaxies at large scales without requiring galaxy counting (See Fig. 1). The speed with whichareas of sky may be measured, relative to source counting, opens new avenues for testing the growth of large-scalestructure. Intrinsic uncertainty due to both source counting noise and sample variance are reduced because of the largesampled volume, enabling higher sensitivity density variation measurements. Redshift information on the structure isobtained at low resolution using submillimeter color information. This measurement of the light emission is compared tothe underlying dark matter distribution to trace the evolution of galaxy bias. EDGE will determine the emission weightedgalaxy bias as a function of redshift, and its dependence on scale-size, to better than 5%.

Knowledge of the variations in the distribution of galaxies on spatial scales ranging from > 200 h−1Mpc, wheredark matter variations are determined directly from Cosmic Microwave Background Radiation (CMBR) anisotropy, to< 5 h−1Mpc where the distribution of dark matter and galaxies is determined from galaxy redshift surveys and theunderlying dynamics of structure growth is non-linear, hold the answers to key unknowns about the origin and earlyevolution of structure.

A strength of the EDGE mission is to span this range of scales and provide a link between these complementarylarge-scale structure probes. EDGE will determine the average large-scale distribution of galaxies from the time when

Further author information: (Send correspondence to SSM)E-mail: [email protected], Telephone: +1 773 702-0097Address: LASR 209; University of Chicago; 5640 S. Ellis Ave.; Chicago, IL 60637, USA

Airborne Telescope Systems II, Ramsey K. Melugin, Hans-Peter Röser, Editors,Proceedings of SPIE Vol. 4857 (2003) © 2003 SPIE · 0277-786X/03/$15.00

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Figure 1. Simulation of the EDGE SkyThis image is a simulation of the CIB fluctuations at 440 GHz. The large map is shown at the EDGE angular resolution.The inset shows a field from Scott et al.1 with protogalaxies identified by red circles. The size of the inset field is aboutone EDGE resolution element.

protogalaxies first ignited to the present time. This will be achieved with a Long Duration Balloon (LDB) platform flyingover Antarctica. EDGE will observe the variation in the CIB in 8 spectral bands ranging from 270 GHz (1,100 µm) to1,500 GHz (200 µm) with 6′ angular resolution over the darkest 400 square degree region of the sky in the SouthernHemisphere.

The resulting large-area map provides a powerful synoptic view of the large-scale distribution of galaxies. The primaryuse for this map will be to measure the emission weighted galaxy bias function as a function of redshift and spatial scale.This bias is the link between the galaxy density and the underlying dark matter distribution. The determination of the biasis an essential element in understanding how the cosmic environment influences the formation of galaxies.

This data set in a previously unexplored parameter space will provide unique opportunities for several secondaryscientific goals. 1) Measure the incoherent “ shot noise” or “confusion noise” fluctuation power in each wavelength band.This is an independent measure of the amplitude of the protogalaxy luminosity function. 2) Measure the wavelengthdependence of the fluctuation power in the Galactic dust at high-galactic latitude. These characteristics of the dust willbe relevant to understanding upcoming satellite measurements of the CMBR anisotropy. 3) Produce limits on emissionvariations of intergalactic dust over the whole sub-mm band. While unlikely to exist in quantity, strong limits on suchdust are important for determining the intrinsic brightness of high redshift supernovas. 4) Discover∼ 20 extremely brightsubmillimeter sources in the EDGE field.

1.1. Large Scale Structure and Galaxy EvolutionStructure in our Universe spans scales ranging from protoplanets in stellar disks, where chemistry and gravitational physicsstand on nearly equal footing, to forming stars and stellar systems where gravity, nuclear physics, and chemistry all play

Proc. of SPIE Vol. 4857 205


significant and complex roles, to the formation of galaxies and clusters of galaxies where gravity alone dominates. Furthercomplicating the modeling of these processes is an unknown species of very weakly interacting dark matter – the total ofwhich outweighs the baryons by a factor of 6.2

µ

Figure 2. Anisotropy of the CIB and Other Astrophysical SourcesThis figure shows the sky brightness variations in four of the EDGE bands from low to high frequency, as labeled at thetop. The CIB fluctuations due to the underlying cosmic density power spectrum are shown in red. The CIB confusion-limited noise is the steeply rising pink line labeled ”shot noise.” The green dots are the 1σ noise level (∆� = 50) forthe baseline EDGE mission. Instrument noise, sky sample variance, and noise due to uncertainty in the CMBR and dustsubtraction are included. The black curve shows the CMBR anisotropy in the two lower frequency bands. The dashedblue curve shows the shape and level of Galactic dust emission variations in the 10% of the sky with the lowest dust.6

The problem of structure evolution on the largest scales is relatively straightforward because the variations are smalland the evolution can be modeled with linear growth theory.3 Also on these large scales, CMBR anisotropy measurementshave constrained the matter variations at z ∼ 1000, providing precise initial conditions for the linear modeling.

The power spectrum of the spatial distribution of galaxies is known on much smaller scales from galaxy redshiftsurveys. A direct comparison between the matter density spectrum and galaxy distribution requires the extrapolation ofthe matter spectrum from much larger scales to scales which are non-linear. The ratio of galaxy density variations tomatter density variations is the “galaxy bias.”

The EDGE mission will span this gap in spatial scales. EDGE will provide information on the large-scale galaxydistribution to be directly compared with the matter power spectrum derived from CMBR anisotropy, using only lineargrowth theory. No extrapolation to scales involving non-linear dynamics is necessary. Noteworthy is the fact that thelinear theory predicts a factor of >100 increase of fluctuation power between z = 1000 and z = 5. If the large-scalefluctuations in CIB brightness are not seen as predicted, it would imply that galaxies may not trace the dark matter or eventhat the dark matter fluctuations do not behave as expected from linear theory.

How do we link the initial conditions given to us by the CMBR to the structure seen in the galaxy redshift surveys?How do we link our knowledge of the linear evolution of structure to the non-linear structures we observe today? The keyto resolving these mysteries is the relationship between the dark matter and the structures on both linear and non-linearscales – the bias. EDGE will probe the redshift dependence of the bias at linear scales linking the primordial fluctuationsto variations in the modern Universe.

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Figure 3. The effect of the redshift dependence of the contribution to the CIB fluctuation powerThis plot shows the contribution to CIB anisotropy fluctuation power from various redshifts. The top panel shows howthe lower frequency bands are weighted to higher redshift for fixed scale size.6 The bottom panel shows the how the sizescales with redshift for the lowest frequency EDGE band. The two dashed lines are identical curves.

1.2. The Link Between Bias and the EDGE ObservationsIt is thought that the CIB is generated by the emission of protogalaxies at redshifts from 0.5 < z < 5.4 Such high redshiftsources are expected to be detectable in the far-infrared since the emission spectrum of the dust brightness, Iν ∝ ν4 from150 to > 2000 GHz in the rest frame of the emitter. This compensates for the (1 + z)4 flux diminution for sources atz ≥ 1. This effect is called the “negative K-correction” of submillimeter sources, and makes the source brightness nearlydistance-independent.

This distance independence continues with increasing redshift until the rest frame frequency where the emission peaks,νp ∼ 2500 GHz, moves into the observation band. At that point, the sensitivity of the band to contributions at higherz falls sharply. For example, observations at frequencies of ∼ 1000 GHz are summing over the galaxy population atredshifts less than 2 while the lower frequency measurements are sensitive to a population with a much higher averagedistance.

For the purposes of designing the EDGE measurements, we need a straightforward model that predicts the fluctuationpower as a function of spatial and spectral frequency. Haiman et al.5 constructed such a model which is further exploredby Knox et al.6 and Magliocchetti et al.7

The model5 for the CIB emission starts with a fit to the COBE FIRAS determined8 spectrum. It assumes that the UVemissivity at each redshift is proportional to the Star-Formation Rate (SFR),9 that dust production is proportional to theSFR, and that the dust has the optical properties proposed by Drain and Lee.10 With the optical properties and radiationbackgrounds specified, the dust temperature follows. The two proportionality constants for the UV emissivity and dustproduction are the fit parameters that specify the model CIB curve. Fig. 2 shows the fluctuation power as a function ofspatial scale for four of the EDGE frequency bands.

Due to the large uncertainties in the Far Infrared Absolute Spectrophotometer (FIRAS) measurements, the fit poorlydetermines the parameters and has large uncertainties. There are no proposed missions addressing the daunting task ofimproving the FIRAS determination of the CIB spectrum. Fortunately, we can use a measurement of the spectrum of the



Figure 4. The decorrelation of fluctuations with frequencyThis plot shows the angular correlation between the fluctuations in the 270 GHz band and two other bands.6 For 1500 GHz,spectrally far from 270 GHz, the correlation is lower because the two bands sample galaxy populations at differentredshifts. This is more pronounced at smaller angular scales because those fluctuations originate from lower redshifts thatare weighted less in the 270 GHz band.

CIB anisotropy — although with the added complication that one is not reconstructing the luminosity density, but theluminosity density weighted by the clustering bias of the sources. A differential measurement of the anisotropy spectrumwill provide higher sensitivity, especially at the lower frequencies. This is especially interesting since the limiting redshift(coldest component) we can reach is determined by the low frequency limit (see Fig. 2).

The Haiman et al.5 model outlined above is used to estimate the CIB anisotropy, given the fit from the CIB spectrummeasurement. At each frequency, the line-of-sight integral of the protogalaxy contribution over redshift is calculated. Themodel takes into account the cosmic geometry, the K-correction, the brightness calculated from the modeled SFR as afunction of redshift and the galaxy biased matter fluctuation power spectrum along the line-of-sight. For the purposes ofmaking conservative predictions for EDGE, we assume a constant galaxy bias of 3. The result of this simple model isshown in Fig. 3, where the contributions to the fluctuations as a function of redshift are shown for different frequencies ata given angular size (top panel) and at different angular sizes for a given frequency (bottom panel). This model quantifiesthe power of the EDGE observations based on reasonable assumptions. The full analysis of the EDGE data will providethe important details on the variation of the source dust properties, particularly with redshift, and refine the model for theSFR.

With the high sensitivity, multiple spectral bands, and large sky coverage provided by EDGE, the differences betweenfrequencies shown in Fig. 3 can be exploited to determine the redshift of the fluctuations. The first result and evidence thatEDGE is detecting different clustered populations at different redshifts will be that the fluctuations will show decorrelationbetween different frequencies. The predicted effect is shown in Fig. 4. Each band is observing a different weighting alongthe line-of-sight integral due to the varying K-corrected spectra.

How well does EDGE determine the parameters of the galaxy distribution? This is tested by modeling the EDGEexperiment according to the sensitivity calculations of Fig. 11 using the scanning coverage of the baseline EDGE mission.The CIB model was used to determine how well the changes in bias and the logarithmic slope of the bias with scale couldbe fit in each of these bands independently. The results are shown in Fig. 5. The top panel shows the relative error in thebias slope to be less than 5% at each redshift independently. The bottom panel shows the relative error in the bias valueitself. Again these errors are in each case less than 5%.



∆∆

Figure 5. EDGE Sensitivity to Model ParametersThe red lines show the forecasted relative errors from EDGE observations on the product of the bias and the CIB bright-ness, jb, (bottom panel, squares) and absolute errors on the bias spectral index parameter, n (top panel, triangles). Themodel has 8 free parameters: jb and n in 4 redshift bins. The baseline mission configuration is assumed. The dashed linesshow the result of a similar calculation for the Planck/HFI instrument.11

2. INSTRUMENTEDGE uses the unique capabilities of the NASA Balloon Program, a new-technology focal plane, and established bal-looning techniques to deliver the sky intensity maps required for precision measurements of the CIB anisotropy.

2.1. GondolaThe EDGE gondola consists of a stabilized platform with a one meter alt-az telescope mounted on it. The platformstabilization is derived from the Sun and is accurate to several degrees. The Telescope servo system operates relativeto the platform. The mechanical layout of the Payload is shown in Fig. 6. of the main EDGE subsystems and theirrelationship to each other.

The azimuthally stabilized gondola provides a Sun-pointed and an anti-Sun side. The electronics, batteries, andvarious mechanisms are placed on the Sun-facing side to be kept warm in the flight environment. The thermal designensures that ambient (∼ 290K) operating temperatures are maintained for all desired subsystems.

Between the Sun and anti-Sun sides is an insulating shield with solar panels mounted on it. The anti-Sun side containsall the cryogenic equipment and includes the Telescope, the Radiometer, and the Gas Cooling System.

2.2. TelescopeThe Telescope system is mounted on the coarse-stabilized gondola platform. The azimuth-elevation mount provides finepointing control for the observations. Pointing is sensed by a Gyroscope which is aligned so that its spin axis along themain telescope beam. The Gyroscope provides short-term guidance information to the Main Computer for tracking theTelescope to an inertial frame (i.e., the sky). Gyroscope drift is evaluated and corrected using a star camera. Coursepointing is derived from the platform position, the GPS latitude and longitude, and encoders on the telescope elevationand azimuth axis.

The optical system is designed to provide a 6′ beam to each of the 7 pixels in the focal plane array and remain under-illuminated for stray light control. An inner Light Shield is carried on the Telescope pointing system to minimize straylight pickup from the Earth and balloon.



Main Electronics Enclosure

Platform Structure

TDRSS High-Gain Antenna Decoupler Mechanism

Battery Box

TelescopeElectronics

Anti-Sun Side Sun Side

(Sun-shade panels along the sidesof the payload not shown for clarity.)1 meter

Momentum Wheel Sun Sensor (4 corners) NSBF Ballast Hopper NSBF SIP Solar Panels

NSBF SIP

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To Balloon

Gas Cooling SystemFlex Line (Schematic)

TelescopeRadiometer

Gas Cooling SystemStorage Cryostat

EDGE Payload Solar Panels

Gondola Layout

Figure 6. EDGE Payload LayoutThe layout of the EDGE payload showing the coarse stabilized platform onto which is mounted the steerable telescope.Some of the ground shielding and sun shielding is not shown for clarity.

The Telescope structure is a low-mass all-Al design that maintains the ground alignment of the Telescope optics,Radiometer, Star Cameras, and Gyroscope during the flight. The azimuth-elevation drives for the Telescope structure areembedded torque motors that control the two axes of motion.

The Primary Mirror is an off-axis section of a paraboloid, 1 meter in diameter. It is a low-mass design using an Alsubstrate. The surface is finished, polished, and overcoated with SiO2 to minimize the operating temperature of the mirror(to reduce thermal loading on the detectors).

The Primary and Secondary Mirrors implement an off-axis telescope system which has been optimized for observationby a single pixel at the chief ray. In the EDGE configuration, with a new secondary mirror, it will provide the nearlywavelength-independent 6′ beam to support the EDGE observations. The Secondary Mirror is a 0.23 meter diameter Almirror.

The Light Shield protects the Primary and Secondary mirrors and the entrance aperture to the Radiometer from straylight. Its main purpose is to ensure that rays of light from the Earth must diffract at least once before illuminating thesecritical optical elements. The Light Shield moves with the Telescope to provide the same protection in all Telescopeorientations. It is a simple two layer sheet aluminum structure.

The temperatures of the Primary and Secondary Mirrors are monitored because the loading on the detectors willchange with these temperatures. We achieve the required 1% monitoring of this loading by measuring the temperaturesof these elements to better than 1 K absolute. These monitors will be placed at a regular spacing on the back side of themirrors. A total of 30 monitors will provide a sufficiently detailed temperature map of the mirrors to correct any effectson the data. These monitors have been built, tested, and qualified as a part of a engineering model telescope.



Photograph of theCryostat

(a) The EDGE Cryostat.

Cross-Sectional Diagramof the Cryostat

FSB Focal Plane

0.25 K

2.8 K20 K

60 K

240 K

Figure 7. EDGE high efficiency cryostat.On the right is a schematic of the EDGE cryostat is a high efficiency, Helium-3 system weighing 10 Kg when loaded withcryogens. Careful super insulation and helical vent tubes reduce the losses.

2.3. RadiometerThe Radiometer consists of a low-mass, long hold-time Cryostat and a Frequency Selective Bolometer (FSB) focal planearray. It provides 56 channels of detector output which are then fed to the Precision Data Acquisition system.

The EDGE Cryostat is an adaptation of the successful design that was used for the TopHat Antarctic flight. It isa novel, low-mass implementation of a 3He evaporation refrigerator. Its detailed design and operation can be found inFixsen et al.12 The design for TopHat provides an 8 day hold-time in flight while keeping the detectors at 250 mK. Aphotograph and diagram of the Cryostat is shown in Fig. 7.

To support at least a ∼ 20 day flight duration needed for EDGE, we will augment the cooling power of the LN2 stageusing cold, 60 K, 4He gas from the Gas Cooling System. The green shaded area was previously used as the LN2 volume,and will be converted into a gas-phase heat exchanger for EDGE.

2.4. DetectorsThe EDGE observations are made possible by the new-technology Frequency Selective Bolometer (FSB) focal planeof Kowitt et al..13 It provides 8 spectral bands and 7 pixels in an extremely compact structure. All 56 detectors op-erate simultaneously, enabling new, high-sensitivity measurements in the far-infrared that require simultaneous spectralinformation. Fig. 9 shows the FSB focal plane array design.



Band 1 - 270 GHz FSB Detector

Termination

gh Frequency BlockersHig(Fluorogold)

Band 8 - 1500 GHz FSB Detector

A Single-Pixel EDGE FSB Stack, 8 spectral bands.

Figure 8. EDGE FSB PixelA schematic of a single pixel of the EDGE radiometer. The light enters from the bottom right as indicated by the redarrow. it passes through a succession of FSB elements, each absorbing only in a narrow band of frequencies startingwith the highest band and passing through to the lowest frequency band and ending in a termination. Each FSB elementconsists of a tuned resonant backshort behind a bolometer with a resonant absorber.

The FSB design uses a tuned absorber in a 5 mm diameter lightguide backed with a tuned backshort λ/4 behind theabsorber. The bolometer is on the absorber, which spans the lightguide diameter. The unit is designed for a specific rangeof absorbing frequencies and transmits the other radiation. This allows the units to be stacked, one behind the other, in acompact, linear structure. Fig. 8 shows a schematic of one of the 7 pixels.

A model of the absorption, transmission, and reflection of the stacks of detector and backshort meshes has beenvalidated using prototype devices. We have fabricated and tested a prototype FSB stack with 4 spectral bands. Fig. 10shows a measurement of the spectral response of this system at the desired cryogenic temperatures. It also shows thespectral response of a conventional bolometer placed behind the 4-band stack, verifying that these elements absorb all theintended wavelengths.

The EDGE FSBs will use a transition edge sensor (TES) as their temperature sensor. The TES provides two advantagesthat are important for an array instrument with a large number of detectors. First, they have much higher fabrication yield.Our previous process for implantation-doped thermistors involves implanting at a variety of doses, and selecting thewafer with the right characteristics. In contrast, our process for TES hits the design characteristics reliably, thus reducingthe number of wafers required. Second, there is existing technology for multiplexing the TES readout through SQUIDmultiplexers, vastly reducing the cryogenic wiring challenge. The multiplexer design has been demonstrated by Benfordetal.14 and Chervenak et al.15 This system will enable us to read out the 56 detectors with a minimum of supportingparts.

2.5. EDGE Observing Strategy and SensitivityThe EDGE advantage in quantifying the CIB anisotropy stems from its ability to separate and determine the spatial andspectral variations from the astrophysical sources.



Figure 9. EDGE FSB focal plane designThe EDGE focal plane consists of a 7 pixel, 8 spectral channel FSB array with a cone fed input. The red block in thefigure is cooled to 2.7K and the gray part with the FSB elements is at 0.28K. The detectors are shown in black and thelow pass absorptive filters are shown in yellow.

The EDGE observing strategy is driven by the following considerations. 1) Reduce dust contamination by selectinga relatively dust-free area of sky to observe. 2) Select the sky coverage dimensions to provide δ� ∼ 50 spatial frequencyresolution. 3) Select the area of sky to yield a per-pixel S/N on the CIB of∼ 4. 4) Reduce effects of instrumental drifts and1/f noise by repeatedly revisiting points at various time scales. 5) Reduce systematics caused by atmospheric emission.

EDGE will observe an area in the Southern Hemisphere between −60◦ < δ < −30◦and 46◦ < α < 85◦. This isone of the darkest areas of sky in the far-infrared, with minimal Galactic dust foreground. This area is also suitable forobservation from a circumpolar balloon, being at a convenient declination and far from the Sun in January.

Fig. 11 gives estimates of the NEP and derived system sensitivity for EDGE. EDGE is background limited except inthe lowest frequency bands, and the background is largely emission from the optics.

EDGE will observe a patch of sky totaling 400 square degrees, which will yield a per-pixel S/N of at least 4 in theCIB-sensitive bands (440 to 1500 GHz). Although a per-pixel S/N of 1 is theoretically optimal for this kind of observation,it leaves no room for the detection of systematics.

EDGE will scan the sky using the successful Boomerang scan strategy,16 adapted to our smaller desired sky area. Thetelescope scans in azimuth 16◦ end-to-end at a fixed elevation of 45◦, tracking in order to keep the center of the scan at afixed right ascension (near 4 hours). Scanning at fixed elevation reduces our sensitivity to atmospheric emission, and therotation of the Earth will cause the area that EDGE covers span a small range in declination, sweeping out the entire areaof the map. Taking into account the size of the array, the scanning, and the rotation of the Earth, at the end of each dayEDGE will have covered a patch of sky about 24.3◦ in declination and 16.3◦ in cross-declination, a total of 400 squaredegrees.



Frequency (GHz)

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Band 3 Model

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Band 1

Band 2Band 3

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Figure 10. Response spectrum of prototype 4 channel FSBThe relative response of the four bands of a prototype FSB pixel is shown on the top panel along with the modeledresponse of the third channel. ON the bottom panel is the spectral response of a conventional bolometer placed at the backof the stack where the termination would normally be. The modeled transmission of the third channel is also shown.

Instrument calibration and systematic checks will be verified by a short daily observation of the Galactic plane usingthe secondary chopper. In addition to beam mapping and calibration, the chopper permits the calibration of the detectorand electronic transfer functions in flight. Once a day at solar noon, EDGE will spend 30 minutes executing a scan atelevation 45◦ across the Galactic plane. These data in comparison to the DIRBE and IRAS maps will allow us to verifythat our beam pattern have not changed from ground measurements before the flight.

ACKNOWLEDGMENTSThe development of the FSB detectors has been supported under NASA grant NAG5-9209. We wish to thank our collab-orators on the TopHat experiment from which many of the EDGE designs are derived. EDGE development is partiallysupported by the NSF Center for Cosmological Physics at the University of Chicago. EDGE focal plane development issupported by the NASA MIDEX Detector Development Program.

REFERENCES1. S. Scott, M. J. Fox, J. A. Dunlap, J. S. Sergent, R. J. Peacock, S. Ivison, R.J. Olivier, R. G. Mann, A. Lawrence, A. Ef-stathiou, M. Rowan-Robinson, D. H. Hughes, E. N. Archibald, A. Blain, and M. Longair, “The scuba 8-mjy survey -i: Sub-millimetre maps, sources and number counts.,” MNRAS , 2001. Submitted, preprint astro-ph/0107446.

2. C. Pryke, N. W. Halverson, E. M. Leitch, J. Kovac, and J. E. Carlstrom, “Cosmological parameter extraction fromthe first season of observations with DASI,” ApJ , 2001. Preprint astro-ph/0104490.



Mission Deploy Frequency(GHz) Npix

Beam(arcmin)

Sensitivity1

MJy/sr/Hz0.5Sensitivity1

uK/sec0.5BLIP2 NEP3

EDGE 2007 270 7 6 0.05 16.1 26 41345 7 6 0.06 11.2 45 58440 7 6 0.07 8.4 69 82560 7 6 0.09 6.8 112 127720 7 6 0.13 5.8 199 219920 7 6 0.16 4.5 312 3371180 7 6 0.22 3.7 538 5721500 7 6 0.29 3.0 903 947

Planck4 2007 100 4 8.8 0.01 13.0

143 3 6.5 0.01 13.0217 6 5 0.01 7.2353 6 5 0.03 5.3857 6 5 0.04 1.1

143P 9 6.5 0.01 10.6217P 8 5 0.01 8.8545P 8 5 0.02 2.3

Hershel5 2007 600 43 0.58 2.3 146

857 88 0.41 3.6 1121199 149 0.29 6.6 106

Good for pointsourcecharacterization.

BLAST6 2002 400 9 1.67 0.45 65

666 36 1.00 1.09 56999 64 0.68 2.05 47

Good for pointsourcecharacterization.

SOFIA7 2005 1499 384 0.15 0.20 2.0

2725 384 0.08 0.65 2.04997 384 0.05 2.17 2.0

High sensitivitybut short flights.

LMT8 2005 143 144 0.19 0.58 654

214 144 0.12 0.98 493273 144 0.10 1.42 439

Excellentsynergy for pointsource followup.

Figure 11. Sensitivity of EDGE and other instruments in the frequency band.The calculated sensitivity of the EDGE detector system. The sensitivity given for all pixels for and the BLIP and NEPgiven on a per detector basis These sensitivities form the basis for the predictions in Fig. 2 and 5.

1Total system sensitivity at the given frequency (all pixels for given mission)2BLIP: Background Limited Performance (per pixel) in 10−18 W/

√Hz3NEP: Noise Equivalent Power (per pixel) in 10−18 W/

√Hz4http://astro.estec.esa.nl/SAgeneral/Projects/Planck/5http://astro.estec.esa.nl/SAgeneral/Projects/First/

6http://www.hep.upenn.edu/blast/7http://sofia.arc.nasa.gov/index.html

8http://www.imfgtym.org

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5. Z. Haiman and L. Knox, “Correlations in the Far-Infrared Background,” ApJ 530, pp. 124–132, Feb. 2000.6. L. Knox, A. Cooray, D. Eisenstein, and Z. Haiman, “Probing early structure formation with far-infrared backgroundcorrelations,” ApJ 550, p. 7, 2001.

7. M. Magliocchetti, L. Moscardini, P. Panuzzo, G. L. Granato, G. De Zotti, and L. Danese, “Theoretical predictionson the clustering of SCUBA galaxies and implications for small-scale fluctuations at submillimetre wavelengths,”MNRAS 325, pp. 1553–1558, Aug. 2001.



8. D. J. Fixsen, E. Dwek, J. C. Mather, C. L. Bennett, and R. A. Shafer, “The spectrum of the extragalactic far-infraredbackground from the cobe FIRAS observations,” ApJ 508, p. 123, 1998.

9. P. Madau, “Starlight in the universe,” in Proceedings of the Nobel Symposium, Particle Physics and the Universe(Enkoping, Sweden, August 20-25, 1998), Physica Scripta , 1999. Preprint astro-ph/9902228.

10. B. T. Draine and H. M. Lee, “Optical properties of interstellar graphite and silicate grains,” ApJ 285, pp. 89–108,Oct. 1984.

11. L. Knox, A. Cooray, D. Eisenstein, and Z. Haiman, “Probing early structure formation with far-infrared backgroundcorrelations,” ApJ , p. in press, 2000.

12. D. J. Fixsen, E. S. Cheng, T. M. Crawford, S. S. Meyer, G. W. Wilson, E. S. Oh, and E. H. Sharp, “Lightweightlong-hold-time dewar,” RSI 72, p. 3112, 2001.

13. M. S. Kowitt, D. J. Fixsen, A. Goldin, and S. S. Meyer, “Frequency selective bolometers,” Appl. Opt. 35, p. 5630,1996.

14. D. J. Benford, C. A. Allen, J. A. Chervenak, M. M. Freund, A. S. Kutyrev, S. H. Moseley, R. A. Shafer, and J. G.Staguhn, “Multiplexed readout of superconducting bolometers,” Int. J. IR MM Waves 21(12), p. 1909, 2000.

15. J. A. Chervenak, K. D. Irwin, E. N. Grossman, J. M. Martinis, C. D. Reintsema, and M. E. Huber, “Superconductingmultiplexer for arrays of transition edge sensors,” App. Phys. Lett. 74, p. 4043, 1999.

16. S. Masi, P. A. R. Ade, R. Artusa, J. J. Bock, and A. B. etal, “Boomerang: a scanning telescope for 10 arcminutesresolution cmb maps.” preprint astro-ph/9812454, 1999.



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