15492121
A Balloon-borne Millimeter-Wave Telescope for Cosmic Microwave Background Anisotropy Measurements
We report on the characteristics and design details of the Medium Scale Anisotropy Measurement (MSAM), a millimeter-wave, balloon-borne telescope that has been used to observe anisotropy in the Cosmic Microwave Background Radiation (CMBR) on 0\fdg5 angular scales. The gondola is capable of determining and maintaining absolute orientation to a few arcminutes during a one-night flight. Emphasis is placed on the optical and pointing performance as well as the weight and power budgets. We also discuss the total balloon/gondola mechanical system. The pendulation from this system is a ubiquitous perturbation on the pointing system. A detailed understanding in these areas is needed for developing the next generation of balloon-borne instruments.
123065208
Detectors for the South Pole Telescope
Abstract The South Pole Telescope (SPT) is a 10–m mm/sub-mm telescope at the Amundsen-Scott South Pole Station. It's primary science goals consist of a galaxy cluster survey for understanding Dark Energy and probing the physics of Inﬂation through the CMB polarization. Both science goals require exceptional sensitivity necessitating focal planes with many optical elements. The focal planes of the SPT utilize Transition Edge Sensor (TES) bolometers to build arrays of nearly 1000 detectors. In this talk, I will present the TES bolometer technology for both the ﬁrst SPT focal plane and its upcoming upgrade to a polarization sensitive array.
6629905
THE OPTICAL DESIGN AND CHARACTERIZATION OF THE MICROWAVE ANISOTROPY PROBE
The primary goal of theMAP satellite, now in orbit, is to make high fidelity polarizatio n sensitive maps of the full sky in five frequency bands between 20 and 100 GHz. From th ese maps we will characterize the properties of the cosmic microwave background (CMB) anisotropy and Galac tic nd extragalactic emission on angular scales ranging from the effective beam size, < 0: Æ23, to the full sky. MAP is a differential microwave radiometer. Two back-to-back shaped offset Gregorian telescopes feed t wo mirror symmetric arrays of ten corrugated feeds. We describe the prelaunch design and characterization of th e optical system, compare the optical models to the measurements, and consider multiple possible sources of sy stematic error.
118946449
An Absolute Measurement of the Cosmic Microwave Background Radiation Temperature at 10.7 GHz
A balloon-borne experiment has measured the absolute temperature of the cosmic microwave background radiation (CMBR) at 10.7 GHz to be TCMBR = 2.730 ± 0.014 K. The error is the quadratic sum of several systematic errors, with a statistical error of less than 0.1 mK. The instrument is made up of a cooled corrugated horn antenna coupled to a total power radiometer. A cryogenic mechanical waveguide switch alternately connects the radiometer to the horn and to an internal reference load. The small measured temperature difference (20 mK) between the sky signal and the reference load in conjunction with the use of a cold front end keeps systematic instrumental corrections small. Atmospheric and window emission are minimized by flying the instrument at 24 km altitude. A large outer ground screen and smaller inner screen shield the instrument from stray radiation from the ground and the balloon. In-flight tests constrain the magnitude of ground radiation contamination, and low-level interference is monitored through observations in several narrow-frequency bands.
17131606
Calibration of the Far Infrared Absolute Spectrophotometer ( FIRAS ) on the Cosmic Background Explorer ( COBE 1 )
The FIRAS instrument on the COBE satellite was designed to accurately measure the spectrum of the cosmic microwave background radiation (CMBR) in the frequency range 1 to 95 cm ?1 with an angular resolution of 7. We describe the calibration of this instrument, including the method of obtaining calibration data, reduction of data, the instrument model, tting the model to the calibration data, and application of the resulting model solution to sky observations. The instrument model ts well for calibration data which resemble sky conditions. The method of propagating detector noise through the calibration process to yield a covariance matrix of the calibrated sky data is described. The nal uncertainties are variable both in frequency and position, but for a typical calibrated sky 2:6 square pixel and 0.7 cm ?1 spectral element the random detector noise limit is of order of a few times 1 The National Aeronautics and Space Administration/Goddard Space Flight Center (NASA/GSFC) is responsible for the design, development, and operation of the Cosmic Background Explorer (COBE). Scientiic guidance is provided by the COBE Science Working Group. GSFC is also responsible for the development of the analysis software and for the production of the mission data sets. { 2 { 10 ?7 erg cm ?2 s ?1 sr ?1 cm for 2 to 20 cm ?1 , and the diierence between the sky and the best t cosmic blackbody can be measured with a gain uncertainty of less than 3%.
15136222
DESIGN, IMPLEMENTATION AND TESTING OF THE MAP RADIOMETERS
The Microwave Anisotropy Probe (MAP) satellite, launched June 30, 2001, will produce full sky maps of the cosmic microwave background radiation in 5 frequency bands spanning 20 106 GHz. MAP contains 20 differential radiometers built with High Electron Mobility Transistor (HEMT) amplifiers with passively cooled input stages. The design and test techniques used to evaluate and minimize systematic errors and the pre-launch performance of the radiometers for all five bands are presented. Subject headings: cosmology: cosmic microwave background—instrumentation: detectors—space vehicles: instruments
58908723
Reconstructing the projected gravitational potential of galaxy clusters from galaxy kinematics
We have developed a method for reconstructing the two-dimensional, projected gravitational potential of galaxy clusters from observed line-of-sight velocity dispersions of cluster galaxies. It is the second in an intended series of papers aiming at a unique reconstruction method for cluster potentials that combine lensing, X-ray, Sunyaev-Zel’dovich and kinematic data. The observed galaxy velocity dispersions are deprojected using the Richardson-Lucy algorithm. The obtained radial velocity dispersions are then related to the gravitational potential by using the tested assumption of a polytropic relation between the e ective galaxy pressure and the density. Once the gravitational potential is obtained in three dimensions, projection along the line of sight yields the two-dimensional potential. For simplicity we adopt spherical symmetry and a known profile for the anisotropy parameter of the galaxy velocity dispersions. We tested the method with a numerically simulated galaxy cluster and the galaxies identified therein and performed the reconstruction for three di erent lines of sight. We extracted a projected velocity-dispersion profile from the simulated cluster and passed it through our algorithm, showing that the deviation between the true and the reconstructed gravitational potential is< 10% within 1:5h 1 Mpc from the cluster centre.
54619228
Joint reconstruction of galaxy clusters from gravitational lensing and thermal gas - I. Outline of a non-parametric method
We present a method to estimate the lensing potential from massive galaxy clusters for given observational X-ray data. The concepts developed and applied in this work can easily be combined with other techniques to infer the lensing potential, e.g. weak gravitational lensing or galaxy kinematics, to obtain an overall best fit model for the lensing potential. After elaborating on the physical details and assumptions the method is based on, we explain how the numerical algorithm itself is implemented with a Richardson-Lucy algorithm as a central part. Our reconstruction method is tested on simulated galaxy clusters with a spherically symmetric NFW density profile filled with gas in hydrostatic equilibrium. We describe in detail how these simulated observational data sets are created and how they need to be fed into our algorithm. We test the robustness of the algorithm against small parameter changes and estimate the quality of the reconstructed lensing potentials. As it turns out we achieve a very high degree of accuracy in reconstructing the lensing potential. The statistical errors remain below 2.0% whereas the systematical error does not exceed 1.0%.