Context. The Sunyaev-Zel’dovich (SZ) effect is a powerful tool for studying clusters of galaxies and cosmology. Large mm-wave telescopes are now routinely detecting and mapping the SZ effect in a number of clusters, measure their comptonisation parameter and use them as probes of the large-scale structure and evolution of the universe. Aims. We show that estimates of the physical parameters of clusters (optical depth, plasma temperature, peculiar velocity, non-thermal components etc.) obtained from ground-based multi-band SZ photometry can be significantly biased, owing to the reduced frequency coverage, to the degeneracy between the parameters and to the presence of a number of independent components larger than the number of frequencies measured. We demonstrate that low-resolution spectroscopic measurements of the SZ effect that also cover frequencies >270 GHz are effective in removing the degeneracy. Methods. We used accurate simulations of observations with lines-of-sight through clusters of galaxies with different experimental configurations (4-band photometers, 6-band photometer, multi-range differential spectrometer, full coverage spectrometers) and different intracluster plasma stratifications. Results. We find that measurements carried out with ground-based few-band photometers are biased towards high electron temperatures and low optical depths, and require coverage of high frequency and/or independent complementary observations to produce unbiased information; a differential spectrometer that covers 4 bands with a resolution of ~6 GHz eliminates most if not all bias; full-range differential spectrometers are the ultimate resource that allows a full recovery of all parameters.

Low-resolution spectroscopy of the Sunyaev-Zel’dovich effect and estimates of cluster parameters / DE BERNARDIS, Paolo; S., Colafrancesco; D'Alessandro, Giuseppe; Lamagna, Luca; P., Marchegiani; Masi, Silvia; Schillaci, Alessandro. - In: ASTRONOMY & ASTROPHYSICS. - ISSN 0004-6361. - 538:(2012), p. A86. [10.1051/0004-6361/201118062]

Low-resolution spectroscopy of the Sunyaev-Zel’dovich effect and estimates of cluster parameters

DE BERNARDIS, Paolo;D'ALESSANDRO, GIUSEPPE;LAMAGNA, Luca;MASI, Silvia;SCHILLACI, ALESSANDRO
2012

Abstract

Context. The Sunyaev-Zel’dovich (SZ) effect is a powerful tool for studying clusters of galaxies and cosmology. Large mm-wave telescopes are now routinely detecting and mapping the SZ effect in a number of clusters, measure their comptonisation parameter and use them as probes of the large-scale structure and evolution of the universe. Aims. We show that estimates of the physical parameters of clusters (optical depth, plasma temperature, peculiar velocity, non-thermal components etc.) obtained from ground-based multi-band SZ photometry can be significantly biased, owing to the reduced frequency coverage, to the degeneracy between the parameters and to the presence of a number of independent components larger than the number of frequencies measured. We demonstrate that low-resolution spectroscopic measurements of the SZ effect that also cover frequencies >270 GHz are effective in removing the degeneracy. Methods. We used accurate simulations of observations with lines-of-sight through clusters of galaxies with different experimental configurations (4-band photometers, 6-band photometer, multi-range differential spectrometer, full coverage spectrometers) and different intracluster plasma stratifications. Results. We find that measurements carried out with ground-based few-band photometers are biased towards high electron temperatures and low optical depths, and require coverage of high frequency and/or independent complementary observations to produce unbiased information; a differential spectrometer that covers 4 bands with a resolution of ~6 GHz eliminates most if not all bias; full-range differential spectrometers are the ultimate resource that allows a full recovery of all parameters.
2012
galaxies: clusters: intracluster medium; cosmic background radiation; techniques: spectroscopic
01 Pubblicazione su rivista::01a Articolo in rivista
Low-resolution spectroscopy of the Sunyaev-Zel’dovich effect and estimates of cluster parameters / DE BERNARDIS, Paolo; S., Colafrancesco; D'Alessandro, Giuseppe; Lamagna, Luca; P., Marchegiani; Masi, Silvia; Schillaci, Alessandro. - In: ASTRONOMY & ASTROPHYSICS. - ISSN 0004-6361. - 538:(2012), p. A86. [10.1051/0004-6361/201118062]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/436555
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