Max Tegmark's cosmology library: wiener

I've now written two sequels to this paper, which containins further improvements.


Figure 1. Where various foregrounds dominate.

The shaded regions indicate where the various foregrounds cause fluctuations exceeding those of COBE-normalized scale-invariant fluctuations, thus posing a substantial challenge to estimation of genuine CMB fluctuations. They correspond to dust (red), free-free emission (cyan), synchrotron radiation (magenta), and point sources (green). The heavy dashed line shows the frequency where the total foreground contribution to each multipole is minimal. The boxes indicate roughly the range of multipoles l and frequencies v probed by various CMB experiments.

Please click here to download a 400K compressed version of the paper, including all the figures (unpack it with "gunzip wiener.ps.gz"). If speed isn't an issue, you can get the 1.5MB uncompressed postscript file by clicking here. If you are interested, two of the figures also come in color versions, experiments_color.ps and everything_color.ps. Click here if you are interested in other research of mine. If the net is slow, try selecting a different flag under "speed" below.
NOTE: Some versions of Netscape stupidly try to display the compressed file as a text file. If this should happen to you, and you face a screen full of gibberish, choose "File-Save As" and save it as "wiener.ps.gz". Some Mosaic versions won't even do this properly, in which case you need to get the uncompressed version above.

A METHOD FOR SUBTRACTING FOREGROUNDS FROM MULTI-FREQUENCY CMB SKY MAPS

Authors:

Max Tegmark & George Efstathiou

Abstract:

An improved method for subtracting contaminants from Cosmic Microwave Background (CMB) sky maps is presented, and used to estimate how well future experiments will be able to recover the primordial CMB fluctuations. We find that the naive method of subtracting foregrounds (such as dust emission, synchrotron radiation, free-free-emission, unresolved point sources, etc) on a pixel by pixel basis can be improved by more than an order of magnitude by taking advantage of the correlation of the emission in neighboring pixels. The optimal multi-frequency subtraction method improves on simple pixel-by-pixel subtraction both by taking noise-levels into account, and by exploiting the fact that most contaminants have angular power spectra that differ substantially from that of the CMB. The results are natural to visualize in the two-dimensional plane with axes defined by multipole l and frequency v. We present a brief overview of the geography of this plane, showing the regions probed by various experiments and where we expect contaminants to dominate. We illustrate the method by estimating how well the proposed ESA COBRAS/SAMBA mission will be able to recover the CMB fluctuations against contaminating foregrounds.

Reference info:

Published in MNRAS, 281, 1297 (1996)

Online references:

This site also contains the latest versions of two other papers of mine that recur in the text; Tegmark & Bunn 1995 and the window function paper Tegmark 1996 ("T96").

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This page was last modified May 20, 1999.
max@ias.edu