arXiv subjects

J. B. Peterson

Publications and source records attributed to J. B. Peterson.

22 records · Page 2Linked to original sources

arXiv1999

Cosmic Microwave Background Observations in the Post-Planck Era

The Microwave Anisotropy Probe and Planck missions will provide low noise maps of the temperature of the cosmic microwave background (CMB). These maps will allow measurement of the power spectrum of the CMB with measurement noise below cosmic variance for l < 1500. It is anticipated that no further all sky CMB temperature observations will be needed after Planck. There are, however, other CMB measurements for which Planck will be not the end but the beginning. Following Planck, precise CMB polarization observations will offer the potential to study physical processes at energies as high as 10^19 GeV. In addition, arcminute scale, multi-frequency observations will allow study of the early phases of the formation of large-scale structure in the universe.

astro-ph↗

arXiv1999

Anisotropy in the Cosmic Microwave Background at Degree Angular Scales: Python V Results

Observations of the microwave sky using the Python telescope in its fifth season of operation at the Amundsen-Scott South Pole Station in Antarctica are presented. The system consists of a 0.75 m off-axis telescope instrumented with a HEMT amplifier-based radiometer having continuum sensitivity from 37-45 GHz in two frequency bands. With a 0.91 deg x 1.02 deg beam the instrument fully sampled 598 deg^2 of sky, including fields measured during the previous four seasons of Python observations. Interpreting the observed fluctuations as anisotropy in the cosmic microwave background, we place constraints on the angular power spectrum of fluctuations in eight multipole bands up to l ~ 260. The observed spectrum is consistent with both the COBE experiment and previous Python results. There is no significant contamination from known foregrounds. The results show a discernible rise in the angular power spectrum from large (l ~ 40) to small (l ~ 200) angular scales. The shape of the observed power spectrum is not a simple linear rise but has a sharply increasing slope starting at l ~ 150.

astro-ph↗

arXiv1997

Using White Dish CMB Anisotropy Data to Probe Open and Flat-Lambda CDM Cosmogonies

We use data from the White Dish experiment to set limits on cosmic microwave background radiation anisotropies in open and spatially-flat-Lambda cold dark matter cosmogonies. We account for the White Dish calibration uncertainty, and marginalize over the offset and gradient removed from the data. Our 2-sigma upper limits are larger than those derived previously. These upper limits are consistent with those derived from the $COBE$-DMR data for all models tested.

astro-ph↗

arXiv1996

Anisotropy in the Microwave Sky at 90 GHz: Results From Python III

The third year of observations with the Python microwave background experiment densely sample a $5.5^o\times 22^o$ region of sky that includes the fields measured during the first two years of observations with this instrument. The sky is sampled in two multipole bands centered at $l \approx 92$ and $l \approx 177$. These two data sets are analyzed to place limits on fluctuations in the microwave sky at 90 GHz. Interpreting the observed fluctuations as anisotropy in the cosmic microwave background we find flat band power estimates of $δT_l\equiv \sqrt{l(l+1)C_l/2π}% =54_{-12}^{+14}μK$ at $l=92_{-24}^{+37}$ and $δT_l=58_{-13}^{+15}μK$ at $l=177_{-58}^{+66}$. Combining the entire three year set of Python observations, we find that the angular power spectrum of fluctuations has a spectral index $m=.02_{-.16}^{+.18}$ and an amplitude $% δT_{l_e}=53_{-11}^{+13}μK$ at $l_e=145_{-74}^{+59}$ for the functional form $δT_l=δT_{l_e}(l/l_e)^m$. The stated uncertainties in the amplitudes and spectral index represent 1$σ$ confidence intervals in the likelihood added in quadrature with a 20\% calibration uncertainty and an estimate of the effects introduced due to imperfect overlap of the beams on the sky. The limits of $l$ are determined from the full width at half maximum of the window functions.

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