survey of the sky at mm and sub-mm wavelengths

Transcription

1 ( OLIMPO An arcmin-resolution survey of the sky at mm and sub-mm wavelengths Federico Nati and OLIMPO Team

2 OLIMPO: the Team Dipartimento di Fisica, La Sapienza, Roma IFAC-CNR, Firenze P.A.R. Ade, P. Mauskopf, A. Orlando, G. Pisano, G. Savini CEA Saclay G. Romeo, L. Salvaterra Univ. of Cardiff, Astronomy A. Boscaleri INGV, Roma S. Masi, M. Calvo, L. Conversi, P. de Bernardis, M. De Petris, G. De Troia, M. Fabrini, L. Lamagna, F. Melchiorri, F. Nati, L. Nati, F. Piacentini, G. Polenta, S. Ricciardi D. Yvon, J.B.Juin, M. Pierre Univ. Of San Diego Y. Rephaeli

3 OLIMPO Is the combination of A large (2.6m 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/sub-mm sky, at 4 frequencies: 150, 220, 340, 540 GHz (wavelengths of 2, 1.4, 0.8, 0.6 mm).

4 Olimpo: list of Science Goals Sunyaev-Zeldovich effect Measurement of Ho from rich clusters of galaxies Cluster counts and detection of early clusters -> cosmological parameters ( n, m..) 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

5 SZ effect CMB Inverse Compton effect of CMB photons against hot electrons in the intergalactic medium of rich clusters of galaxies 150 GHz Cluster ee- 220 GHz US

6 OLIMPO: Simulations We want see how OLIMPO can separate the different components; the parameters are that of a typical Λ-CDM cosmology (S-Z simulations from Y. Rephaeli; analysis by L. Conversi)

7 CMB anisotropy SZ clusters Galaxies 150 GHz 220 GHz 340 GHz 540 GHz mm-wave sky vs OLIMPO arrays 30 Simulations by P. Mauskopf

8 The uniqueness of OLIMPO OLIMPO measures in 4 frequency bands simultaneously. These bands optimally sample the spectrum of the SZ effect. This allows us to clean the signal from any dust and CMB contamination, and even to measure Te by means of the relativistic corrections.

9 Simulations show that: For a Y=10-4 cluster, in a dust optical depth of 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 +10-5, TCMB can be measured to +10 K Te can be measured to +3keV Many clusters (order 100) can be observed in a long duration flight

10 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 1o/s, amplitude of the scans 3op-p, detector noise 150 K s1/2, 1/f knee = 0.1 Hz, total observing time = 4 hours, comptonization parameter for the cluster y= o 3o

11 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 (or will be) available from XMM/Chandra Number Cluster A168 A400 A426 A539 A576 A754 A1060 A1185 A1215 A1254 z Number Cluster A1317 A1367 A1656 A1775 A1795 A2151 A2199 A2256 A2319 A2634 z

12 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 have 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.

13 Distant clusters produce the same SZ as nearby ones. OLIMPO is able to detect clusters never seen in the X-rays. The number density of these clusters strongly depends on the expansion history, i.e. on. The higher resolution and sensitivity wrt Planck will allow deeper observations. The multifrequency observation will allow a cleaner removal of high frequency foregrounds

14 3500 OLIMPO l=30 20 detectors, 150 K rt(s) 10 days 4 arcmin FWHM 300 square degrees l(l+1)c l / 2 ( K2) multipole Compare! BOOMERanG l=30 6 detectors, 150 K rt(s) 10 days 12 arcmin FWHM 2000 square degrees l(l+1)c l CMB anisotropy 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 BOOMERanG, 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 and to measure darkmatter Power Spectrum (a.u.) multipole

15 There are additional AGNs lost in the confusion of the CMB fluctuations. WOMBAT catalog The WOMBAT catalogue and tools predict quite well the flux observed for the 3 detected AGN, 100 and can be used to estimate the contamination due to unresolved AGNs. In the 3% of the sky mapped by B98 the contamination of the PS 10 at 150 GHz is less than 0.3% at l=200, and less than 8% at l=600. This is reduced by 50% if the resolved sources (at 150 GHz) are 1 removed, and by 80% if are removed those resolved at 41 Flux 150 GHz GHz. counts

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

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

19 Olimpo: The Primary mirror The primary mirror (2.6m) 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

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

21 Telescope Cassegrain f/# Cassegrain 3.48 Max Diam = 2600mm Primary Mirror Min Diam = 300mm RCurv = 2495mm Conic constant = Diam = 520mm Secondary Mirror RCurv = 708mm Conic constant = Reimaging Optics 2 Spherical Mirrors + Spherical Lyot Stop Max Diam = 54mm Lyot Stop Min Diam = 12mm RCurv = 175mm 3rd & 5th Mirrors Diam = 172mm RCurv = 350mm Efective f/# 3.44 F.o.v. per pixel 5 arcmin Total F.o.v. 15 x 20 arcmin Optimization Zemax and Physical Optics

22 Focal Plane Splitters 5th Mirror Lyot Stop 3rd Mirror

23 Cold optics integration

24 Modulation system primary mirror scans the sky across the elevation angle 1 wide, about 1 /s triangular wave rotation around center of mass

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

26 Mirrors integration Telescope integration and mirrors position adjusting

27 Inner frame attitude control elevation angle is controlled by a linear actuator and a 16 bit encoder primary is moved by a step motor and its position is monitored by a LVDT. A programmable board perform a feedback control.

28 Encoders Elevation angle is measured by a 16 bit encoder

29 Star camera for pointing reconstruction and its dedicated PC104 onboard computer CCD camera for pointing reconstruction

30 Warm optics test Angular response of the primary and secondary mirror Gunn oscillator at 90 Ghz, low noise HEMT amplifier and diode receiver in the telescope focus Far field for 90 Ghz, 2.6 m diameter: about 5 Km From Tor Vergata area to Villa Mondragone (up to the hills near Rome, a beautiful XVI century villa in the famous Castelli Romani, chosen also by Galileo for resolution tests of his telescope) Gunn modulated at 83 Hz, reference signal for Lock-in sent through radio transmitter

31 The telescope is integrate d with half of the gondola. The whole system is mounted onto a rotating platform for beam measuring

32 Risposta angolare 2 D 2 Area CNR 5 km 90 GHz Villa Mondragone

33 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)

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35 4) Long Duration Cryogenics We need a Long Duration Balloon to produce a sizeable catalog of clusters. Detectors must operate remotely at 0.3K for weeks Solutions: Long Duration LN/L4He Cryostat and 3He Fridge

36 The dewar is being developed in Rome. It is based on the same successfull design of the BOOMERanG dewar Masi et al. 1998, days at 290 mk.

37 Cryostat tests

38 5) Long Duration Balloon Flights We need many days of observation from the stratospher to produce a sizeable catalog of clusters. Solution: Polar Long Duration Balloon Flights

39 Svalbard launch tests Test launch July 24, 2004 Feasibility of LDB flight from Svalbard proved More than 40 days at float IRIDIUM telemetry subsystem for OLIMPO succesfully tested Solar panels/charge control tested Forecasted OLIMPO LDB scientific balloon flight in Summer 2006

40 6) Telemetry / TC / data acquisition for Long Duration Balloon Flights Polar flights are not in Line of Sight. Solution: a) Satellite relay telemetry system Iridium for selected/compressed data b) on-board full storage

41 Iridium 66 satellites Trasfer rate per channel 2400 bps On board data encoding and storage Master 4ADC Multi

42 Executive Summary: - OLIMPO is approved in the ASI program - The payload will be ready for a flight on July 2007 from Svalbard - Development work has been very productive - Cryogenics, Optics and electronics tests are good waiting for detectors integration and testing