MAXIPOL: a balloon-borne experiment for measuring the polarization anisotropy of the cosmic microwave background radiation

We discuss MAXIPOL, a bolometric balloon-borne experiment designed to measure the E-mode polarization anisotropy of the cosmic microwave background radiation (CMB) on angular scales of 10 arcmin to 2 degrees. MAXIPOL is the first CMB experiment to collect data with a polarimeter that utilizes a rotating half-wave plate and fixed wire-grid polarizer. We present the instrument design, elaborate on the polarimeter strategy and show the instrument performance during flight with some time domain data. Our primary data set was collected during a 26 hour turnaround flight that was launched from the National Scientific Ballooning Facility in Ft. Sumner, New Mexico in May 2003. During this flight five regions of the sky were mapped. Data analysis is in progress

Correlations Between the WMAP and MAXIMA Cosmic Microwave Background Anisotropy Maps

We cross-correlate the cosmic microwave background temperature anisotropy maps from the WMAP, MAXIMA-I, and MAXIMA-II experiments. We use the cross-spectrum, which is the spherical harmonic transform of the angular two-point correlation function, to quantify the correlation as a function of angular scale. We find that the three possible pairs of cross-spectra are in close agreement with each other and with the power spectra of the individual maps. The probability that there is no correlation between the maps is smaller than 1 * 10^(-8). We also calculate power spectra for maps made of differences between pairs of maps, and show that they are consistent with no signal. The results conclusively show that the three experiments not only display the same statistical properties of the CMB anisotropy, but also detect the same features wherever the observed sky areas overlap. We conclude that the contribution of systematic errors to these maps is negligible and that MAXIMA and WMAP have accurately mapped the cosmic microwave background anisotropy

Cosmological implications of the MAXIMA-1 high-resolution cosmic microwave background anisotropy measurement

We discuss the cosmological implications of the new constraints on the power spectrum of the cosmic microwave background (CMB) anisotropy derived from a new high-resolution analysis of the MAXIMA-1 measurement. The power spectrum indicates excess power at l similar to 860 over the average level of power at 411 less than or equal to l less than or equal to 785. This excess is statistically significant at the similar to 95% confidence level. Its position coincides with that of the third acoustic peak, as predicted by generic inflationary models selected to fit the first acoustic peak as observed in the data. The height of the excess power agrees with the predictions of a family of inflationary models with cosmological parameters that are fixed to fit the CMB data previously provided by BOOMERANG-LDB and MAXIMA-1 experiments. Our results therefore lend support for inflationary models and more generally for the dominance of adiabatic coherent perturbations in the structure formation of the universe. At the same time, they seem to disfavor a large variety of the nonstandard (but inflation-based) models that have been proposed to improve the quality of fits to the CMB data and the consistency with other cosmological observables. Within standard inflationary models, our results combined with the COBE/Differential Microwave Radiometer data give best-fit values and 95% confidence limits for the baryon density, Omega (b)h(2) similar or equal to 0.033 +/- 0.013, and the total density, Omega = 0.9(-0.16)(+0.18). The primordial spectrum slope (n(s)) and the optical depth to the last scattering surface (tau (c)) are found to be degenerate and to obey the relation n(s) similar or equal to (0.99 +/- 0.14) + 0.46 tau (c), for tau (c) less than or equal to 0.5 (all at 95% confidence levels)

Simultaneous FAST and Double Star TC1 observations of broadband electrons during a storm time substorm

Broadband electrons (BBEs) exhibit remarkable electron flux enhancements over a broad energy range (0.03-30 keV) near the equatorward edge of the auroral oval during geomagnetic storms. Here, we report a BBE event observed by the Fast Auroral Snapshot (FAST) satellite at 1355-1359 UT, similar to 61 degrees-66 degrees invariant latitudes, similar to 0600 magnetic local time (MLT), and similar to 3800 km altitude during a storm on 25 July 2004. The Double Star (DS) TC1 satellite was located near the magnetic equator at L = 5.7, close to the same local time as FAST. We investigate the acceleration process of BBEs from the inner magnetosphere to near the ionosphere by comparing electron data obtained by FAST and DS TC1. We also investigate both plasma and field variations in the inner magnetosphere associated with substorm onset using DS TC1 data to examine the relationship between the BBEs and the storm time substorm. Ground geomagnetic field data show a positive H-bay at similar to 1349 UT at similar to 0600 MLT, indicating that a storm time substorm started just before the appearance of the BBEs. At similar to 1350 UT, a tailward ion flow was observed by DS TC1. Then, DS TC1 observed a local dipolarization and a drastic ion density enhancement at similar to 1351 UT, indicating that particle heating associated with the substorm was occurring in the inner magnetosphere. From similar to 1352 UT, electron fluxes were isotropically enhanced at energies above similar to 0.5 keV as observed by DS TC1. On the other hand, the pitch angle distribution of BBEs at the FAST altitude showed field-aligned lower-energy electrons below similar to 0.5 keV and isotropic higher-energy electrons above similar to 0.5 keV. From these data, it was inferred that the BBEs might consist of two energy components due to the acceleration or heating of electrons at different altitudes in association with the storm time substorm

A high spatial resolution analysis of the MAXIMA-1 cosmic microwave background anisotropy data

We extend the analysis of the MAXIMA-1 cosmic microwave background data to smaller angular scales. MAXIMA, a bolometric balloon-borne experiment, mapped a 124 deg(2) region of the sky with 10' resolution at frequencies of 150, 240, and 410 GHz during its first flight. The original analysis, which covered the multipole range 36 less than or equal to l less than or equal to 785 using a 100 deg(2) map, is extended to l = 1235 using a subset of the data from three 150 GHz photometers in the fully cross-linked central 60 deg(2) of the map. The main improvement over the original analysis is the use of 3' square pixels in the calculation of the map. The new analysis is consistent with the original for l 785, where inflationary models predict a third acoustic peak, the new analysis shows power with an amplitude of 56 +/- 7 muK at l similar or equal to 850 in excess to the average power of 42 +/- 3 muK in the range 441 < l < 785

MAXIMA: A Balloon-Borne Cosmic Microwave Background Anisotropy Experiment

We describe the Millimeter wave Anisotropy eXperiment IMaging Array (MAXIMA), a balloon-borne experiment designed to measure the temperature anisotropy of the Cosmic Microwave Background (CMB) on angular scales of 10' to 5 degrees . MAXIMA mapped the CMB using 16 bolometric detectors in spectral bands centered at 150 GHz, 240 GHz, and 410 GHz, with 10' resolution at all frequencies. The combined receiver sensitivity to CMB anisotropy was ~40 microK/rt(sec). Systematic parasitic contributions were minimized by using four uncorrelated spatial modulations, thorough crosslinking, multiple independent CMB observations, heavily baffled optics, and strong spectral discrimination. Pointing reconstruction was accurate to 1', and absolute calibration was better than 4%. Two MAXIMA flights with more than 8.5 hours of CMB observations have mapped a total of 300 deg^2 of the sky in regions of negligible known foreground emission. MAXIMA results have been released in previous publications. MAXIMA maps, power spectra and correlation matrices are publicly available at http://cosmology.berkeley.edu/maxim