Recent CMB Observations

Abstract

The study of the Universe using anisotropies of the Cosmic Microwave Background (CMB) have advanced significantly in the last year and will continue to advance at a rapid pace. In this paper I will discuss the medium angular resolution temperature anisotropy data from WMAP and ARCHEOPS, the medium angular resolution polarization anisotropy data from WMAP and DASIPOL, and the high angular resolution temperature anisotropy from ACBAR and CBI.Ever since the discovery [1] of the cosmic microwave background (CMB) it has provided information crucial to our understanding of the Universe. The initial indications of a blackbody spectrum for the CMB finally settled the Big Bang vs. Steady State controversy in favor of the hot Big Bang. The discoveries of the dipole anisotropy [2,3,4,5] revealed the velocity of the Solar System relative to the rest of the observable Universe and demonstrated the existence of fairly large peculiar velocities. The very precise blackbody spectrum found by FIRAS [6] on COBE [7] ruled out explosive scenarios for the formation of large scale structure (LSS), the discovery of the primary anisotropy of the CMB [8] by the DMR [9] on COBE showed that cold dark matter (CDM) dominated models with a primordial perturbation power spectrum P´kµ ∝ k n with n 1 could explain the LSS using gravity alone. Calculations [10] of the CMB anisotropies in CDM models showed the existence of acoustic peaks in the CMB anisotropy angular power spectrum C at a spherical harmonic index p1 200 (about a 1 AE angular scale). The location in space of these acoustic peaks could be used to measure the total density of the Universe, Ω tot , [11] or equivalently the geometry of space.Observations [12] aimed at the acoustic peaks started even before the DMR detection of the anisotropy and these efforts only accelerated once the existence of ∆T s was certain. The first suspicion of the acoustic peak [13] in 1994 was followed by several ground and balloon-borne experiments [14] leading to a consensus location of the first acoustic peak at p1 210 ¦ 15 at the beginning of 2000 [15]. The balloon-borne BOOMERanG experiment [16] then announced a much more precise value of p1 197 ¦ 6. By mid summer 2002 results had been reported from many other experiments such as the ground-based single dish TOCO [17]; the ground based interferometers VSA [18], CBI [19] & DASI [20]; and the balloon-borne MAXIMA [21].This paper will concentrate on the more recent CMB results, reported in the past two years, which have provided a spectacular advance in our understanding of the Universe. LARGE AREA OBSERVATIONSThe experiments reported observations of large parts of the sky. The ARCHEOPS balloon-borne experiment [22] observed more than 30% of the sky in one night with excellent sensitivity. Covering a large part of the sky allowed an accurate measurement of the acoustic peak maximum at p1 220 ¦ 6.But the ARCHEOPS results were superseded by the results from the Wilkinson Microwave Anisotropy Probe (WMAP) [23], which observed 100% of the sky in five different...

Optimal map-making with singularities

“…Moreover, the eigen-problem of a real-valued system commonly necessitates resolution within the complex space. Meanwhile, it is also possible to deal with the singularity problem by means of limits, like the one shown in [38], which is often implemented by the use of an additional small matrix; however, this will inevitably propagate the side effect to all modes, which will not happen in the above general solution. Even if for the simplified solution in section A.5.2, the side effect will be strictly limited within the missing modes.…”

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“…Consequently, x Z < x A , where x = x Z is the solution of χ C (x) = 0, and x = x A is the solution of χC (x) = 0: Recent observations of the power spectrum of the CMB radiation [10,11,12] show that the maximal value of the temperature anisotropy, ∆T , is approximately 80µK, and is attained for perturbations with the wavenumber l ≈ 200, that corresponds to the angular size of nearly 1 degree [12,13,14,15]. (The numbers in the graphs in Refs.…”

“…Recent observations of the power spectrum of the CMB radiation [10,11,12] show that the maximal value of the temperature anisotropy, ∆T , is approximately 80µK, [12,13,14,15]. (The numbers in the graphs in Refs.…”

“…(The numbers in the graphs in Refs. [13] - [15] imply that the "angular size" meant here is the radius rather than diameter of the perturbation.) Consequently, one might take 80µK as the upper limit of temperature variation and 1…”