English

UCSB South Pole 1994 CMB anisotropy measurement constraints on open and flat-Lambda CDM cosmogonies

Astrophysics 2008-11-26 v2

Abstract

We develop methods to account for experimental and observational uncertainties in likelihood analyses of data from cosmic microwave background (CMB) anisotropy experiments and apply them to an analysis of the UCSB South Pole 1994 (SP94) experiment. Observationally motivated open and spatially-flat Λ\Lambda, cold dark matter cosmogonies are considered. Among the models we consider, the full SP94 data set is most consistent with Ω00.10.2\Omega_0 \sim 0.1-0.2 open models and less so with old (t0\gap1516Gyr)(t_0 \gap 15 - 16 Gyr), high baryon density (ΩB\gap0.0175h2)(\Omega_B \gap 0.0175 h^{-2}), low density (Ω00.20.4),flat\Omega_0 \sim 0.2 - 0.4), flat-\Lambdamodels.TheSP94datadonotruleoutanyofthemodelsweconsideratthe models. The SP94 data do not rule out any of the models we consider at the 2\sigmalevel.TheSP94experimentismostsensitivetoanisotropiesonasomewhatlarger,modeldependent,angularscalethanthescaleatwhichthewindowfunctionpeaks.ForestablishingthesignificanceofadetectionofCMBanisotropywederivelimitsusingthehighestposteriordensity(HPD)prescription,sinceityieldssmallerlowerlimits.SinceHPDlimitsleadtotighterconstraintsontheCMBamplitude,theyalsoprovideforgreaterdiscriminationbetweenmodels.ModelnormalizationsdeducedfromtheSP94datasubsetsaremostlyconsistentwiththosededucedfromthetwoyearCOBEDMRdata,althoughtheKabanddatapreferanormalization level. The SP94 experiment is most sensitive to anisotropies on a somewhat larger, model-dependent, angular scale than the scale at which the window function peaks. For establishing the significance of a detection of CMB anisotropy we derive limits using the highest posterior density (HPD) prescription, since it yields smaller lower limits. Since HPD limits lead to tighter constraints on the CMB amplitude, they also provide for greater discrimination between models. Model normalizations deduced from the SP94 data subsets are mostly consistent with those deduced from the two-year COBE-DMR data, although the Ka-band data prefer a normalization \sim 1\sigmalowerthandotheQbanddata,theQandKa+Qdatafavouraslightlyhighernormalizationforthe lower than do the Q-band data, the Q and Ka + Q data favour a slightly higher normalization for the \Omega_0 = 0.1openmodelthandoestheDMR,andtheKaandKa+Qdatapreferasomewhatlowernormalizationfortheolder,higher open model than does the DMR, and the Ka and Ka + Q data prefer a somewhat lower normalization for the older, higher \Omega_B,lowdensity, low-density \Lambda$ models than does the DMR.

Keywords

Cite

@article{arxiv.astro-ph/9602141,
  title  = {UCSB South Pole 1994 CMB anisotropy measurement constraints on open and flat-Lambda CDM cosmogonies},
  author = {Ken Ganga and Bharat Ratra and Josh Gundersen and Naoshi Sugiyama},
  journal= {arXiv preprint arXiv:astro-ph/9602141},
  year   = {2008}
}

Comments

Substantially shortened and rewritten. Accepted by ApJ. PostScript. 49 pages of text + tables. 16 pages of figures