Maximum-likelihood estimation of the cosmic microwave background power spectrum from interferometer observations

Hobson, M.; Maisinger, Klaus

doi:10.1046/j.1365-8711.2002.05524.x

Cited by 67 publications

(94 citation statements)

References 25 publications

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“…Measurement of the CMB power spectrum with interferometers has been discussed in several papers (e.g., Hobson, Lasenby, & Jones 1995;Maisinger, Hobson, & Lasenby 1997;White et al 1999aWhite et al , 1999bNg 2001;Hobson & Maisinger 2002), and details of the method that we have used are presented in Paper IV. A single-baseline interferometer is sensitive to a range of multipoles l % 2 u AE Dl=2, where u is the baseline length in wavelengths and Dl is the FWHM of the visibility window function, which is proportional to the square of the Fourier transform of the primary beam (antenna power pattern).…”

Section: The Cosmic Background Imagermentioning

confidence: 99%

The Anisotropy of the Microwave Background tol= 3500: Mosaic Observations with the Cosmic Background Imager

Pearson

Mason

Readhead

et al. 2003

ApJ

265

157

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Using the Cosmic Background Imager (CBI), a 13-element interferometer array operating in the 26-36 GHz frequency band, we have observed 40 deg 2 of sky in three pairs of fields, each $145 0 Â 165 0 , using overlapping pointings (mosaicking). We present images and power spectra of the cosmic microwave background radiation in these mosaic fields. We remove ground radiation and other low-level contaminating signals by differencing matched observations of the fields in each pair. The primary foreground contamination is due to point sources (radio galaxies and quasars). We have subtracted the strongest sources from the data using higher resolution measurements, and we have projected out the response to other sources of known position in the power spectrum analysis. The images show features on scales $6 0 -15 0 , corresponding to masses $ð5 80Þ Â 10 14 M at the surface of last scattering, which are likely to be the seeds of clusters of galaxies. The power spectrum estimates have a resolution Dl % 200 and are consistent with earlier results in the multipole range ld1000. The power spectrum is detected with high signal-to-noise ratio in the range 300dld1700. For 1700dld3000 the observations are consistent with the results from more sensitive CBI deep field observations. The results agree with the extrapolation of cosmological models fitted to observations at lower l and show the predicted drop at high l (the '' damping tail '').

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Section: The Cosmic Background Imagermentioning

confidence: 99%

The Anisotropy of the Microwave Background tol= 3500: Mosaic Observations with the Cosmic Background Imager

Pearson

Mason

Readhead

et al. 2003

ApJ

265

157

View full text Add to dashboard Cite

show abstract

“…The measurement is done directly in Fourier space which makes interferometers ideal instruments for measuring the angular power spectrum of the sky signal. The visibility based power spectrum estimator formalism has been extensively used for analyzing CMB data from interferometers (Hobson et al 1995;White et al 1999;Hobson et al 2002;Myers et al 2003). A visibility based estimator has also been successfully employed to study the power spectrum of the HI in the interstellar medium (ISM) of several nearby galaxies ( e.g.…”

Section: Introductionmentioning

confidence: 99%

Visibility-based angular power spectrum estimation in low-frequency radio interferometric observations

Choudhuri¹,

Bharadwaj²,

Ghosh³

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We present two estimators to quantify the angular power spectrum of the sky signal directly from the visibilities measured in radio interferometric observations. This is relevant for both the foregrounds and the cosmological 21-cm signal buried therein. The discussion here is restricted to the Galactic synchrotron radiation, the most dominant foreground component after point source removal. Our theoretical analysis is validated using simulations at 150 MHz, mainly for GMRT and also briefly for LO-FAR. The Bare Estimator uses pairwise correlations of the measured visibilities, while the Tapered Gridded Estimator uses the visibilities after gridding in the uv plane. The former is very precise, but computationally expensive for large data. The latter has a lower precision, but takes less computation time which is proportional to the data volume. The latter also allows tapering of the sky response leading to sidelobe suppression, an useful ingredient for foreground removal. Both estimators avoid the positive bias that arises due to the system noise. We consider amplitude and phase errors of the gain, and the w-term as possible sources of errors . We find that the estimated angular power spectrum is exponentially sensitive to the variance of the phase errors but insensitive to amplitude errors. The statistical uncertainties of the estimators are affected by both amplitude and phase errors. The w-term does not have a significant effect at the angular scales of our interest. We propose the Tapered Gridded Estimator as an effective tool to observationally quantify both foregrounds and the cosmological 21-cm signal.

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“…The second term denotes the noise due to primordial CMB anisotropies and contains significant off-diagonal elements, both between visibility positions and between frequencies. This term can be calculated from a given primary CMB power spectrum C CMB l (ν) following A128, page 10 of 20 Hobson & Maisinger (2002); note that in intensity units the CMB power spectrum is a function of frequency. To calculate this term, we adopt the best-fitting CMB power spectrum to the WMAP 7-year data (Komatsu et al 2011).…”

Section: Analysis Of Ami Datamentioning

confidence: 99%

Planckintermediate results

Ade¹,

Aghanim²,

Arnaud³

et al. 2013

A&A

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A comparison is presented of Sunyaev-Zeldovich measurements for 11 galaxy clusters as obtained by Planck and by the ground-based interferometer, the Arcminute Microkelvin Imager. Assuming a universal spherically-symmetric Generalised Navarro, Frenk and White (GNFW) model for the cluster gas pressure profile, we jointly constrain the integrated Compton-Y parameter (Y 500 ) and the scale radius (θ 500 ) of each cluster. Our resulting constraints in the Y 500 − θ 500 2D parameter space derived from the two instruments overlap significantly for eight of the clusters, although, overall, there is a tendency for AMI to find the Sunyaev-Zeldovich signal to be smaller in angular size and fainter than Planck. Significant discrepancies exist for the three remaining clusters in the sample, namely A1413, A1914, and the newly-discovered Planck cluster PLCKESZ G139.59+24.18. The robustness of the analysis of both the Planck and AMI data is demonstrated through the use of detailed simulations, which also discount confusion from residual point (radio) sources and from diffuse astrophysical foregrounds as possible explanations for the discrepancies found. For a subset of our cluster sample, we have investigated the dependence of our results on the assumed pressure profile by repeating the analysis adopting the best-fitting GNFW profile shape which best matches X-ray observations. Adopting the best-fitting profile shape from the X-ray data does not, in general, resolve the discrepancies found in this subset of five clusters. Though based on a small sample, our results suggest that the adopted GNFW model may not be sufficiently flexible to describe clusters universally.

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Maximum-likelihood estimation of the cosmic microwave background power spectrum from interferometer observations

Cited by 67 publications

References 25 publications

The Anisotropy of the Microwave Background tol= 3500: Mosaic Observations with the Cosmic Background Imager

The Anisotropy of the Microwave Background tol= 3500: Mosaic Observations with the Cosmic Background Imager

Visibility-based angular power spectrum estimation in low-frequency radio interferometric observations

Planckintermediate results

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