The Sky Polarization Observatory

Abstract The Sky Polarization Observatory (SPOrt) is an ASI-funded experiment specifically designed to measure the sky polarization at 22, 32 and 90 GHz, which was selected in 1997 by ESA to be flown on the International Space Station. Starting in 2006 and for at least 18 months, it will be taking direct and simultaneous measurements of the Stokes parameters Q and U at 660 sky pixels, with FWHM=7°. Due to development efforts over the past few years, the design specifications have been significantly improved with respect to the first proposal. Here we present an up-to-date description of the instrument, which now warrants a pixel sensitivity of 1.7 μK for the polarization of the cosmic background radiation, assuming two years of observations. We discuss SPOrt scientific goals in the light of WMAP results, in particular in connection with the emerging double-reionization cosmological scenario.

[1]  Edward J. Wollack,et al.  First year Wilkinson Microwave Anisotropy Probe (WMAP) observations: Determination of cosmological parameters , 2003, astro-ph/0302209.

[2]  D. Schlegel,et al.  Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds , 1997, astro-ph/9710327.

[3]  The angular power spectra of polarized Galactic synchrotron , 2000, astro-ph/0006387.

[4]  R. Tascone,et al.  Limits due to instrumental polarisation in CMB experiments at microwave wavelengths , 2001 .

[5]  A. R. Duncan,et al.  Polarized radio emission over the southern Galactic plane at 2.4 GHz , 1997 .

[6]  Christopher W. O'Dell,et al.  A Limit on the Large Angular Scale Polarization of the Cosmic Microwave Background , 2001 .

[7]  A. Lazarian,et al.  Diffuse Galactic Emission from Spinning Dust Grains , 1997, astro-ph/9710152.

[8]  On the Threshold of the Reionization Epoch , 2001, astro-ph/0108069.

[9]  U. Seljak,et al.  An all sky analysis of polarization in the microwave background , 1996, astro-ph/9609170.

[10]  P. Peebles,et al.  Cosmological consequences of a rolling homogeneous scalar field. , 1988, Physical review. D, Particles and fields.

[11]  The power-law behaviours of angular spectra of polarized Galactic synchrotron , 2002, astro-ph/0202389.

[12]  Jérôme Martin,et al.  Quintessence and supergravity , 1999, astro-ph/9905040.

[13]  Edward J. Wollack.  High‐electron‐mobility‐transistor gain stability and its design implications for wide band millimeter wave receivers , 1995 .

[14]  T. N. Gautier,et al.  A calculation of confusion noise due to infrared cirrus , 1992 .

[15]  U. Minnesota,et al.  Radio Polarization from the Inner Galaxy at Arcminute Resolution , 2000, astro-ph/0010518.

[16]  Scott Dodelson,et al.  Determining Cosmic Microwave Background Anisotropies in the Presence of Foregrounds , 1995, astro-ph/9512021.

[17]  P. Martini,et al.  Coevolution of Black Holes and Galaxies , 2004 .

[18]  P. Reich,et al.  A 1.4 GHZ RADIO CONTINUUM AND POLARIZATION SURVEY AT MEDIUM GALACTIC LATITUDES : II. FIRST SECTION , 1999, astro-ph/9905023.

[19]  Max Tegmark,et al.  How to measure CMB polarization power spectra without losing information , 2001 .

[20]  E. Hivon,et al.  The Planck-LFI instrument: analysis of the 1/f noise and implications for the scanning strategy , 1999 .

[21]  Abraham Loeb,et al.  The Reionization of the Universe by the First Stars and Quasars , 2001 .

[22]  A. Melchiorri,et al.  A flat Universe from high-resolution maps of the cosmic microwave background radiation , 2000, Nature.

[23]  George D. Nicolson,et al.  The Rhodes/HartRAO 2326‐MHz radio continuum survey , 1998 .

[24]  J. Kaplan,et al.  Destriping of polarized data in a CMB mission with a circular scanning strategy , 2000 .

[25]  R. Davis,et al.  1°- and 25-scale interferometric surveys in the northern sky at 5 GHz , 2000 .

[26]  M. Zaldarriaga.  Cosmic Microwave Background Polarization Experiments , 1998 .

[27]  Alexander S. Szalay,et al.  Evidence for Reionization at z ∼ 6: Detection of a Gunn-Peterson Trough in a z = 6.28 Quasar , 2001, astro-ph/0108097.

[28]  Carl Heiles.  9286 Stars: An Agglomeration of Stellar Polarization Catalogs , 2000 .

[29]  D. J. Fixsen,et al.  Calibrator Design for the COBE Far Infrared Absolute Spectrophotometer (FIRAS) , 1998, astro-ph/9810373.

[30]  Merrifield,et al.  GALAXY EVOLUTION: THEORY AND OBSERVATIONS , 2003 .

[31]  Uros Seljak,et al.  Measuring Polarization in the Cosmic Microwave Background , 1996, astro-ph/9608131.

[32]  L. Toffolatti,et al.  Extragalactic source counts and contributions to the anisotropies of the cosmic microwave background: predictions for the Planck Surveyor mission , 1998 .

[33]  G. Hinshaw,et al.  Structure in the COBE differential microwave radiometer first-year maps , 1992 .

[34]  B. Ciardi,et al.  Early reionization by the first galaxies , 2003 .

[35]  Simon Prunet,et al.  Statistical Properties of Galactic Starlight Polarization , 2001, astro-ph/0105023.

[36]  J. Carlstrom,et al.  Detection of polarization in the cosmic microwave background using DASI , 2002, Nature.

[37]  Early Metal Enrichment of the Intergalactic Medium by Pregalactic Outflows , 2000, astro-ph/0010158.

[38]  Garching,et al.  The angular power spectrum of radio emission at 2.3 GHz , 2001, astro-ph/0103233.

[39]  C. Sbarra,et al.  Astrophysical Polarized Backgrounds , 2002 .

[40]  Robustness of quintessence , 1999, astro-ph/9912046.

[41]  A. Maselli,et al.  CRASH: A radiative transfer scheme , 2003, astro-ph/0307117.

[42]  On the Evolution of the Ionizing Emissivity of Galaxies and Quasars Required by the Hydrogen Reionization , 2002, astro-ph/0211071.

[43]  Edward J. Wollack,et al.  First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Foreground Emission , 2003, astro-ph/0302208.

[44]  Albert Stebbins,et al.  A Probe of Primordial Gravity Waves and Vorticity , 1997 .

[45]  Magnetic Dipole Microwave Emission from Dust Grains , 1998, astro-ph/9807009.

[46]  Edward L. Wright.  Angular Power Spectra of the COBE DIRBE Maps , 1998 .

[47]  Charles L. Bennett,et al.  High-Latitude Galactic Emission in the COBE Differential Microwave Radiometer 2 Year Sky Maps , 1996 .

[48]  A. Melchiorri,et al.  A Measurement by BOOMERANG of Multiple Peaks in the Angular Power Spectrum of the Cosmic Microwave Background , 2001, astro-ph/0104460.

[49]  J. Delabrouille,et al.  Analysis of the accuracy of a destriping method for future cosmic microwave background mapping with the PLANCK SURVEYOR satellite , 1998 .

[50]  Max Tegmark,et al.  Foregrounds and Forecasts for the Cosmic Microwave Background , 2000 .

[51]  Max Tegmark,et al.  CMB mapping experiments: a designer's guide , 1997 .

[52]  F. Rohrlich,et al.  Spin‐s Spherical Harmonics and ð , 1967 .

[53]  D. Weinberg,et al.  Reionization and the Abundance of Galactic Satellites , 2000, astro-ph/0002214.

[54]  The Universe Was Reionized Twice , 2002, astro-ph/0210473.

[55]  Samuel Harvey Moseley,et al.  A Preliminary measurement of the Cosmic Microwave Background spectrum by the Cosmic Background Explorer (COBE) satellite , 1990 .

[56]  M. Tucci,et al.  Polarization Angular Spectra of Galactic Synchrotron Emission on Arcminute Scales , 2002, astro-ph/0207237.

[57]  G. Giardino,et al.  Towards a model of full-sky Galactic synchrotron intensity and linear polarisation: A re-analysis of the Parkes data , 2002, astro-ph/0202520.

[58]  D. Schlegel,et al.  Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation Foregrounds , 1998 .

[59]  T. Broadhurst,et al.  The Influence of Galactic Outflows on the Formation of Nearby Dwarf Galaxies , 2000, The Astrophysical journal.

[60]  Max Tegmark,et al.  A method for subtracting foregrounds from multifrequency CMB sky maps , 1996 .

[61]  Nature of dark energy and polarization measurements , 2003, astro-ph/0301215.

[62]  T. Itoh.  Numerical techniques for microwave and millimeter-wave passive structures , 1989 .

[63]  Albert Stebbins,et al.  Statistics of cosmic microwave background polarization , 1997 .

[64]  An iterative destriping technique for diffuse background polarization data , 2003, astro-ph/0302276.

[65]  U. Seljak,et al.  Signature of gravity waves in polarization of the microwave background , 1996, astro-ph/9609169.

[66]  William A. Fowler,et al.  On relativistic astrophysics. , 1964 .

[67]  E. Dwek.  Unveiling the cosmic infrared background , 1996 .