1994/02/16 by J. Richard Bond, Bond, J. Richard
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #Radio Astronomy Observations and Technology #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9402043
11 pages, LaTeX, uses revtex; 3 postscript figs, capri_powf*.eps, via anonymous ftp to ftp.cita.utoronto.ca, cd to /pub/dick/capri; CITA-94-5
arxiv created 1994/02/16 · openalex publication_date 1994/02/16 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The natural outcome of theoretical calculations of microwave background anisotropy is the angular power spectrum \cal C_ℓ as a function of multipole number ℓ. Experimental \cal C_ℓ's are needed for direct comparison. Estimation procedures using statistics linear in the pixel amplitudes as well as the conventional but less useful quadratic combinations are described. For most current experiments, a single broad-band power amplitude is all that one can get with accuracy. Results are given for the Capri-meeting detections. Mapping experiments, sensitive to many base-lines, can also give spectral ``colour'' information, either with a series of contiguous narrow-band powers or as parameterized by a local ``colour'' index nΔT (scale invariant is -2, white noise is 0). Bayesian analyses of the full first year DMR and FIRS maps give very similar band-powers (\eg Qrms,PS=17.9 ± 2.9 μK \it c.f. 18.6 ± 4.7 μK for nΔT=-2) and colour indices (with 1 and 2 sigma error bars) nΔT+3=2.0+0.4;+0.7-0.4;-1.0 and 1.8+0.6;+0.9-0.8;-1.3 (\it c.f. the value 1.15 for a ``standard'' scale invariant CDM model). The 53 and 90 GHz DMR maps, as well as the FIRS map, have residual short-distance noise which steepens nΔT. Allowing the pixel error bars to increase absorbs much of the residual, but further exploration is needed to see if a second residual evident in the data which is responsible for the high nΔT is from systematic errors or is physical.