http oberon roma 1 infn itolimpo OLIMPO An

(http: //oberon. roma 1. infn. it/olimpo) OLIMPO An arcmin-resolution survey of the sky at mm and sub-mm wavelengths Silvia Masi Dipartimento di Fisica La Sapienza, Roma and the OLIMPO team

Spectroscopic surveys (SDSS, 2 d. F) have now mapped the 3 D large scale structure of the Universe at distances up to 1000 Mpc 4 G ly rom us e f c n ta dis Clusters of Galaxies are evident features of this distribution. But when did they form ? How did gravity coagulate them from the unstructured early universe, and was this process affected by the presence of Dark Energy ?

OLIMPO and clusters • Answer these questions in a completely independent way is one of the science goals of the OLIMPO mission. • Observing clusters of galaxies in the microwaves, this telescope has the ability to detect them at larger distances (and earlier times) than optical and X-ray observations. • The number count of clusters at early times is one very sensitive to the presence and kind of Dark Energy and Dark Matter in the Universe, so OLIMPO can provide timely and important data for the current cosmology paradigm.

Inverse Compton scattering of CMB photons against hot electrons in the intergalactic medium of rich clusters of galaxies SZ effect [CMB through cluster – CMB] (m. Jy/sr) CMB g Cluster ee- g US About 1% of the photons acquire about 1% boost in energy, thus slightly shifting the spectrum of CMB to higher frequencies.

S-Z • • • SZ effect has been detected in several clusters (see e. g. Birkinshaw M. , Phys. Rept. 310, 97, (1999) astro-ph/9808050 for a review, and e. g. Carlstrom J. E. et al. , astro-ph/0103480 for current perspectives) The order of magnitude of the relative change of energy of the photons is Dn/n ˜ k. Te/mec 2 ˜ 10 -2 for 10 ke. V e-, and the probability of scattering in a typical cluster is n L ˜ 10 -2. So we expect a CMB temperature change DT/T ˜ (n L)(k. Te/mec 2)˜ 10 -4. The strength of the effect does not depend on the distance of the Cluster ! So it is possible to see very distant clusters (not visible in optical/X).

Carlstrom J. , et al. Astro-ph/0208192 ARAA 2002 The SZ signal from the clusters does not depend on redshift.

mm observations of the SZ • However, these detections are at cm wavelengths. At mm wavelengths, the (positive) SZ effect has been detected only in a few clusters. • Expecially for distant and new clusters (in the absence of an optical/X template) both cm (negative) and mm (positive) detections are necessary to provide convincing evidence of a detection. • The Earth atmosphere is a strong emitter of mm radiation. • An instrument devoted to mm/submm observations of the SZ must be carried outside the Earth atmosphere using a space carrier. • Stratospheric balloons (40 km), sounding rockets (400 km) or satellites (400 km to 106 km. . ) have been heavily used for CMB research.

At balloon altitude (41 km): At 90 and 150 GHz balloon observations can be O 2 CMB-noise limited & Ozone lines

CMB anisotropy SZ clusters Galaxies Total @ 150 GHz mm-wave sky at 150 GHz

OLIMPO • Is the combination of – A large (2. 6 m diameter) mm/sub-mm telescope with scanning capabilities – A multifrequency array of bolometers – A precision attitude control system – A long duration balloon flight • The results will be high resolution (arcmin) sensitive maps of the mm/submm sky, with optimal frequency coverage (150, 220, 340, 540 GHz) for SZ detection, Determination of Cluster parameters and control of foreground/background contamination.

CMB anisotropy SZ clusters Galaxies 150 GHz 220 GHz 340 GHz 540 GHz 30’ mm-wave sky vs OLIMPO arrays

The uniqueness of OLIMPO • OLIMPO measures in 4 frequency bands simultaneously. These bands optimally sample the spectrum of the SZ effect. • Opposite signals at 410 GHz and at 150 GHz provide a clear signature of the SZ detection. • 4 bands allow to clean the signal from any dust and CMB contamination, and even to measure Te. - 0 + +

OLIMPO observations of a SZ Cluster • Simulated observation of a SZ cluster at 2 mm with the Olimpo array. • The large scale signals are CMB anisotropy. • The cluster is the dark spot evident in the middle of the figure. • Parameters of this simulation: comptonization parameter for the cluster y=10 -4 ; scans at 1 o/s, amplitude of the scans 3 o p-p, detector noise 150 m. K s 1/2, 1/f knee = 0. 1 Hz, total observing time = 4 hours 3 o 3 o

Simulations show that: • For a – Y=10 -5 cluster, – in a dust optical depth of 10 -5 @ 1 mm, – In presence of a 100 K CMB anisotropy • In 2 hours of integration over 1 square degree of sky centered on the cluster – Y can be determined to +10 -6, – DTCMB can be measured to +10 K – Te can be measured to +3 ke. V

Clusters sample • We have selected 40 nearby rich clusters to be measured in a single long duration flight. • For all these clusters high quality data are available from XMM/Chandra Number 1 2 3 4 5 6 7 8 9 10 Cluster A 168 A 400 A 426 A 539 A 576 A 754 A 1060 A 1185 A 1215 A 1254 z 0. 0452 0. 0232 0. 0183 0. 0205 0. 0381 0. 0528 0. 0114 0. 0304 0. 0494 0. 0628 Number 11 12 13 14 15 16 17 18 19 20 Cluster A 1317 A 1367 A 1656 A 1775 A 1795 A 2151 A 2199 A 2256 A 2319 A 2634 z 0. 0695 0. 0215 0. 0232 0. 0696 0. 0616 0. 0371 0. 0303 0. 0601 0. 0564 0. 0312

Corrections • For each cluster, applying deprojection algorithms to the SZ and X images (see eg Zaroubi et al. 1999), and assuming hydrostatic equilibrium, it is possible to derive the gas profile and the total (including dark) mass of the cluster. • The presence of 4 channels (and especially the 1. 3 mm one) is used to estimate the peculiar velocity of the cluster. • Both these effects must be monitored in order to correct the determination of Ho (see e. g. Holtzapfel et al. 1997). • It should be stressed that residual systematics, i. e. cluster morphology and small-scale clumping, have opposite effects in the determination of Ho • Despite the relative large scatter of results for a single cluster, we expect to be able to measure Ho to 5% accuracy from our 40 clusters sample.

• The XMM-LSS and MEGACAM survey region is centered at dec=-5 deg and RA=2 h 20', and covers 8 ox 8 o. It is observable in a trans-mediterranean flight, like the one we can do to qualify OLIMPO. • During the test flight we will observe the target region for 2 hours at good elevation, without interference from the moon and the sun. • Assuming 19 detectors working for each frequency channel, and a conservative noise of 150 KCMBs 1/2, we can have as many as 5600 independent 8' pixels with a noise per pixel of 7 KCMB for each of the 2 and 1. 4 mm bands. Olimpo vs XMM The correlations could provide: Ø Relative behavior of clusters (Dark Matter) potential, galaxies and clusters X-ray gas. Ø Detailed tests of structure formation models. ØCosmological parameters and structure formation

Clusters and L • Since Y depends on n (and not on n 2), clusters can be seen with SZ effect at distances larger than with X-ray surveys. • There is the potential to discover new clusters and to map the evolution of clusters of galaxies in the Universe. • This is strongly related to L.

Simulations show that the background from unresolved SZ clusters is very sensitive to L (see e. g. Da Silva et al. astro-ph/0011187) L=0. 7 L=0. 0

Diffuse SZ effect • A hint for this is present in recent CBI data. Bond et al, astro-ph/0205384, 5, 6, 78 • The problem is that the measurement was single wavelength (30 GHz), and used an interferometer. (A bolometric follow-up by ACBAR was not sensitive enough to confirm this measurement). • OLIMPO is complementary in two ways: it is single dish and works at four , much higher , frequencies.

Olimpo: list of Science Goals • Sunyaev-Zeldovich effect – Measurement of Ho from rich clusters – Cluster counts and detection of early clusters -> parameters (L) • CMB anisotropy at high multipoles – The damping tail in the power spectrum – Complement interferometers at high frequency • Distant Galaxies – Far IR background – Anisotropy of the FIRB – Cosmic star formation history • Cold dust in the ISM – Pre-stellar objects – Temperature of the Cirrus / Diffuse component

Power Spectrum (a. u. ) • Taking advantage of its high angular resolution, and concentrating on a limited area of the sky, OLIMPO will be able to measure the angular power spectrum (PS) of the CMB up to multipoles l » 3000, significantly higher than BOOMERan. G, MAP and Planck. • In this way it will complement at high frequencies the interferometers surveys, producing essential independent information, in a wide frequency interval, and free from systematics like sources subtraction. • The measurement of the damping tail of the PS is an excellent way to map the dark matter distribution (4) and to measure darkmatter (5). Power Spectrum (a. u. ) Olimpo: CMB anisotropy Compare!

Gi om m i & C ol af ra n ce sc o 20 03 Power spectrum of unresolved AGNs

mm/sub-mm backgrounds • Diffuse cosmological emission in the mm/submm is largely unexplored. • A cosmic far IR background (FIRB) has been discovered by COBE -FIRAS (Puget, Hauser, Fixsen) • It is believed to be produced by ultraluminous early galaxies (Blain astroph/0202228) • Strong, negative kcorrection at mm and sub -mm wavelengths enhances the detection rate of these early galaxies at high redshift.

mm/sub-mm galaxies • In the sub-mm we are in the steeply rising part of the emission spectrum: if the galaxy is moved at high redshift we will see emission from a rest-frame wavelength closer to the peak of emission. z = 0 z > 0 B B no n n n o(1+z) Blain, astro-ph/0202228

Olimpo: Cold Cirrus Dust • Sub-mm observations of cirrus clouds in our Galaxy are very effective in measuring the temperature and mass of the dust clouds. • See Masi et al. Ap. J. , 553 L 93 -L 96, 2001; and Masi et al. “Interstellar dust in the BOOMERan. G maps”, in “BC 2 K 1”, De Petris and Gervasi editors, AIP 616, 2001.

OLIMPO can be used to survey the galactic plane for pre-stellar objects OLIMPO M 16 - In the constellation Serpens The SED of L 1544 with 10 1 second sensitivities

OLIMPO: the Team • Dipartimento di Fisica, La Sapienza, Roma – S. Masi, et al. • IFAC-CNR, Firenze – A. Boscaleri et al. • INGV, Roma – G. Romeo et al. • Astronomy, University of Cardiff – P. Mauskopf et al. • CEA Saclay – D. Yvon et al. • CRTBT Grenoble – P. Camus et al. • Univ. Of San Diego / Tel Aviv – Y. Rephaeli et al.

Technology Challenges for OLIMPO: 1) Angular resolution – size of telescope 2) 3) 4) 5) 6) Scan strategy Detector Arrays & readout Long Duration Cryogenics Long Duration Balloon Flights Telemetry, TC, data acquisition for LDB

1) Angular Resolution & Telescope Size We need few arcmin resolution @ 2 mm wavelength: this requires a >2 m mirror.

Olimpo: The Primary mirror • The primary mirror (2. 6 m) has been built and verified. • 50 m accuracy at large scales; nearly optical polishing. • It is the largest mirror ever flown on a stratospheric balloon. • It is slowly wobbled to scan the sky. Test of the OLIMPO mirror at the ASI L. Broglio base in Trapani

Olimpo: The Payload The inner frame can point from 0 o to 60 o of elevation. Structural analysis complies to NASA standards.

Telescope Cassegrain f/# Cassegrain 3. 48 Max Diam = 2600 mm Primary Mirror Min Diam = 300 mm RCurv = 2495 mm Conic constant = -1. 009 Diam = 520 mm Secondary Mirror RCurv = 708 mm Conic constant = -2. 11 Reimaging Optics 2 Spherical Mirrors + Spherical Lyot Stop Max Diam = 54 mm Lyot Stop Min Diam = 12 mm RCurv = 175 mm 3 rd & 5 th Mirrors Diam = 172 mm RCurv = 350 mm Efective f/# 3. 44 F. o. v. per pixel 5 arcmin Total F. o. v. 15 x 20 arcmin Optimization Zemax and Physical Optics

Telescope test @ IASF Roma, March 2006

Olimpo: reimaging optics • The cryogenic reimaging optics is being developed in Rome. • It is mounted in the experiment section of the cryostat, at 2 K, while the bolometers are cooled at 0. 3 K. • Extensive baffling and a cold Lyot stop reduce significantly straylight and sidelobes.

Focal Plane Splitters 5 th Mirror Lyot Stop 3 rd Mirror

2) Scan Strategy We need to scan the sky at 0. 1 deg/s or more in order to avoid 1/f noise and drifts in the detectors. Solutions: a) scanning primary b) optimized map-making software

$The OLIMPO telescope has been optimized for diffraction limited performance at 0. 5 mm,$

The OLIMPO telescope has been optimized for diffraction limited performance at 0. 5 mm, even in the tilted configuration of the primary.

The primary modulator is ready and currently being integrated on the payload

Data cleaning : TOD de-spiking And we have a complete data pipeline, tested on BOOMERan. G, very complete and efficient…

Data co-adding: one data chunk

Data co-adding: naive combination of chunks

Data co-adding: optimal map-making

OLIMPO observations of a SZ Cluster • Simulated observation of a SZ cluster at 2 mm with the Olimpo array. • The large scale signals are CMB anisotropy. • The cluster is the dark spot evident in the middle of the figure. • Parameters of this observation: scans at 1 o/s, amplitude of the scans 3 op-p, detector noise 150 m. K s 1/2, 1/f knee = 0. 1 Hz, total observing time = 4 hours, comptonization parameter for the cluster y=10 -4. 3 o 3 o

3) Detector Arrays & Readout We need a) large format bolometer arrays b) multiplex readout Solutions: a) photolitgraphed TES b) SQUID series arrays and multiplexer (f)

Photon noise limit for the CMB

Polarization-sensitive bolometers JPL-Caltech 3 m thick wire grids, Separated by 60 m, in the same groove of a circular corrugated waveguide Planck-HFI testbed B. Jones et al. Astro-ph/0209132

Bolometer Arrays • Once bolometers reach BLIP conditions (CMB BLIP), the mapping speed can only be increased by creating large bolometer arrays. • BOLOCAM and MAMBO are examples of large arrays with hybrid components (Si wafer + Ge sensors) • Techniques to build fully litographed arrays for the CMB are being developed. • TES offer the natural sensors. (A. Lee, D. Benford, A. Golding …) Bolocam Wafer (CSO) MAMBO (MPIf. R for IRAM)

Cryogenic Bolometers • A large a is important for high responsivity. • Ge thermistors: • Superconducting transition edge thermistors: S. F. Lee et al. Appl. Opt. 37 3391 (1998)

TES arrays • Are the future of this field. See recent reviews from Paul Richards, Adrian Lee, Jamie Bock, Harvey Moseley … et al. • In Proc. of the Far-IR, sub-mm and mm detector technology workshop, Monterey 2002.

Why TES are good: 1. Durability - TES devices are made and tested for X-ray to last years without degradation 2. Sensitivity - Have achieved few x 10 -18 W/ Hz at 100 m. K good enough for CMB and ground based spectroscopy 3. Speed is theoretically few s, for optimum bias still less than 1 ms - good enough 4. Ease of fabrication - Only need photolithography, no e-beam, no glue 5. Multiplexing with SQUIDs either TDM or FDM, impedances are well matched to SQUID readout 6. 1/f noise is measured to be low What is difficult: 1. Not so easy to integrate into receiver SQUIDs are difficult part 2. Coupling to microwaves with antenna and matched heater thermally connected to TES - able to optimize absorption and readout separately

PROTOTYPE FULLY LITOGRAPHED SINGLE PIXEL - 150 GHz (Mauskopf, Orlando) Similar to JPL design, Hunt, et al. , 2002 but with waveguide coupled antenna Silicon nitride Waveguide Absorber/ termination Nb Microstrip TES Radial probe Thermal links

PROTOTYPE FULLY LITOGRAPHED SINGLE PIXEL - 150 GHz (Mauskopf) Details: TES Thermal links Absorber - Ti/Au: 0. 5 /square - t = 20 nm Need total R = 5 -10 w = 5 m d = 50 m Microstrip line: h = 0. 3 m, = 4. 5 Z ~ 5

receiver (1 pixel of 1000) filter Cryo: 0. 3 K Space qual. load TES stripline antenna TES for mm waves (Cardiff, Phil Mauskopf) … and many others … membrane island SQUID Readout MUX Si substrate with Si 3 N 4 film 150 m

3) Detector Arrays & Readout We need a) large format bolometer arrays b) multiplex readout Solutions: a) photolitgraphed TES b) SQUID series arrays and multiplexer (f)

frequency-domain multiplexing row i bias row i+1 bias j Ref: Berkeley/NIST design j+1

Cryogenic Resonant Filters • We have developed cryogenic resonant filters for the MUX. Based on 5 m. H Nb wire Inductors and MICA Capacitors • Measured Q around 1000

4) Long Duration Cryogenics We need a Long Duration Balloon to produce a sizeable catalog of clusters. Detectors must operate remotely at 0. 3 K for weeks Solutions: Long Duration LN/L 4 He Cryostat and 3 He Fridge

• The dewar is being developed in Rome. It is based on the same successfull design of the BOOMERan. G dewar • Masi et al. 1998, 1999 • 25 days at 290 m. K.

Images of the OLIMPO cryostat

Test of the OLIMPO cryostat

OLIMPO is now included in the 20062008 planning of the Italian Space Agency 1 st flight Jul. 2007 2 nd flight Jul. 2008 The baseline flight will be LDB from SVALBARD

OLIMPO will soon shed light on the “Dark Ages” between cosmic recombination (z=1000) and cosmic dawn (z=10).