347 research outputs found
Polarized galactic synchrotron and dust emission and their correlation
We present an analysis of the level of polarized dust and synchrotron
emission using the WMAP9 and Planck data. The primary goal of this study is to
inform the assessment of foreground contamination in the cosmic microwave
background (CMB) measurements below from 23 to 353 GHz. We
compute angular power spectra as a function of sky cut based on the Planck 353
GHz polarization maps. Our primary findings are the following. (1) There is a
spatial correlation between the dust emission as measured by Planck at 353 GHz
and the synchrotron emission as measured by WMAP at 23 GHz with
or greater for and ,
dropping to for . (2) A simple foreground model
with dust, synchrotron, and their correlation fits well to all possible cross
spectra formed with the WMAP and Planck 353 GHz data given the current
uncertainties. (3) In the 50 cleanest region of the polarized dust map, the
ratio of synchrotron to dust amplitudes at 90 GHz for 50 110 is
. Smaller regions of sky can be cleaner although the
uncertainties in our knowledge of synchrotron emission are larger. A
high-sensitivity measurement of synchrotron below 90 GHz will be important for
understanding all the components of foreground emission near 90 GHz.Comment: 10 pages, 8 figures; Published in JCAP. Source masks updated, minor
change
The Amplitude and Spectral Index of the Large Angular Scale Anisotropy in the Cosmic Microwave Background Radiation
In many cosmological models, the large angular scale anisotropy in the cosmic
microwave background is parameterized by a spectral index, , and a
quadrupolar amplitude, . For a Peebles-Harrison-Zel'dovich spectrum, .
Using data from the Far Infra-Red Survey (FIRS) and a new statistical measure,
a contour plot of the likelihood for cosmological models for which
and is obtained. We find that the likelihood is
maximum at . For constant the likelihood falls to
half its maximum at and and for constant the
likelihood falls to half its maximum at and . Regardless
of , the likelihood is always less than half its maximum for and
for , as it is for .Comment: Ten Page
Mapping the CMB III: combined analysis of QMAP flights
We present results from the QMAP balloon experiment, which maps the Cosmic
Microwave Background (CMB) and probes its angular power spectrum on degree
scales. In two separate flights, data were taken in six channels at two
frequency bands between 26 to 46 GHz. We describe our method for mapmaking
(removal of 1/f-noise and scan-synchronous offsets) and power spectrum
estimation, as well as the results of a joint analysis of the data from both
flights. This produces a 527 square degree map of the CMB around the North
Celestial Pole, allowing a wide variety of systematic cross-checks. The
frequency dependence of the fluctuations is consistent with CMB and
inconsistent with Galactic foreground emission. The anisotropy is measured in
three multipole bands from l~40 to l~200, and the angular power spectrum shows
a distinct rise which is consistent with the Saskatoon results.Comment: 4 pages, with 3 figures included. Submitted to ApJL. Window functions
are available at http://pupgg.princeton.edu/~cmb/welcome.html and color
figures and links at http://www.sns.ias.edu/~angelica/skymap.html#qma
A Degree-Scale Measurement of the Anisotropy in the Cosmic Microwave Background
We report the detection of anisotropy in the microwave sky at 3O GHz and at l deg angular scales. The most economical interpretation of the data is that the fluctuations are intrinsic to the cosmic microwave background. However, galactic free-free emission is ruled out with only 90% confidence. The most likely root-mean-squared amplitude of the fluctuations, assuming they are described by a Gaussian auto-correlation function with a coherence angle of 1.2 deg, is 41(+16/-13) (mu)K. We also present limits on the anisotropy of the polarization of the cosmic microwave background
Galactic emission at 19 GHz
We cross-correlate a 19 GHz full sky Cosmic Microwave Background (CMB) survey
with other maps to quantify the foreground contribution. Correlations are
detected with the Diffuse Infrared Background Experiment (DIRBE) 240, 140 and
100 micron maps at high latitudes (|b|>30degrees), and marginal correlations
are detected with the Haslam 408 MHz and the Reich & Reich 1420 MHz synchrotron
maps. The former agree well with extrapolations from higher frequencies probed
by the COBE DMR and Saskatoon experiments and are consistent with both
free-free and rotating dust grain emission.Comment: 4 pages, with 4 figures included. Accepted for publication in ApJL.
Color figure and links at http://www.sns.ias.edu/~angelica/foreground.html#19
or from [email protected]
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