Examinando por Autor "Lasenby, A.N."

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    Comparison of Sunyaev-Zel'dovich measurements from Planck and from the Arcminute Microkelvin Imager for 99 galaxy clusters
    (EDP Sciences, 2015-08) Perrott, Y.C.; Olamaie, M.; Rumsey, C.; Brown, M.L.; Feroz, F.; Grainge, K.J.B.; Hobson, M.P.; Lasenby, A.N.; MacTavish, C.J.; Pooley, G.G.; Saunders, R.D.E.; Schammel, M.P.; Scott, P.F.; Shimwell, T.W.; Titterington, D.J.; Waldram, E.M.; Aghanim, N.; Arnaud, M.; Ashdown, M.; Aussel, H.; Barrena, R.; Bikmaev, I.; Böhringer, H.; Burenin, R.; Carvalho, P.; Chon, G.; Comis, B.; Dahle, H.; Democles, J.; Douspis, M.; Harrison, D.; Hempel, A.; Hurier, G.; Khamitov, I.; Kneissl, R.; MacÍas-Pérez, J.F.; Melin, J.-B.; Pointecouteau, E.; Pratt, G.W.; Rubiño-Martín, J.A.; Stolyarov, V.; Sutton, D.
    We present observations and analysis of a sample of 123 galaxy clusters from the 2013 Planck catalogue of Sunyaev-Zel'dovich sources with the Arcminute Microkelvin Imager (AMI), a ground-based radio interferometer. AMI provides an independent measurement with higher angular resolution, 3 arcmin compared to the Planck beams of 5-10 arcmin. The AMI observations thus provide validation of the cluster detections, improved positional estimates, and a consistency check on the fitted size (θs) and flux (Ytot) parameters in the generalised Navarro, Frenk and White (GNFW) model. We detect 99 of the clusters. We use the AMI positional estimates to check the positional estimates and error-bars produced by the Planck algorithms PowellSnakes and MMF3. We find that Ytot values as measured by AMI are biased downwards with respect to the Planck constraints, especially for high Planck-S/N clusters. We perform simulations to show that this can be explained by deviation from the universal pressure profile shape used to model the clusters. We show that AMI data can constrain the α and β parameters describing the shape of the profile in the GNFW model for individual clusters provided careful attention is paid to the degeneracies between parameters, but one requires information on a wider range of angular scales than are present in AMI data alone to correctly constrain all parameters simultaneously. © 2015 ESO.
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    Optical validation and characterization of Planck PSZ1 sources at the Canary Islands observatories: I. First year of ITP13 observations
    (EDP Sciences, 2018-08) Barrena, R.; Streblyanska, A.; Ferragamo, A.; Rubiño-Martín, J.A.; Aguado-Barahona, A.; Tramonte, D.; Génova-Santos, R.T.; Hempel, A.; Lietzen, H.; Aghanim, N.; Arnaud, M.; Böhringer, H.; Chon, G.; Democles, J.; Dahle, H.; Douspis, M.; Lasenby, A.N.; Mazzotta, P.; Melin, J.B.; Pointecouteau, E.; Pratt, G.W.; Rossetti, M.; Van Der Burg, R.F.J.
    We have identified new clusters and characterized previously unknown Planck Sunyaev-Zeldovich (SZ) sources from the first Planck catalogue of SZ sources (PSZ1). The results presented here correspond to an optical follow-up observational programme developed during approximately one year (2014) at Roque de los Muchachos Observatory, using the 2.5 m Isaac Newton telescope, the 3.5 m Telescopio Nazionale Galileo, the 4.2 m William Herschel telescope and the 10.4 m Gran Telescopio Canarias. We have characterized 115 new PSZ1 sources using deep optical imaging and spectroscopy. We adopted robust criteria in order to consolidate the SZ counterparts by analysing the optical richness, the 2D galaxy distribution, and velocity dispersions of clusters. Confirmed counterparts are considered to be validated if they are rich structures, well aligned with the Planck PSZ1 coordinate and show relatively high velocity dispersion. Following this classification, we confirm 53 clusters, which means that 46% of this PSZ1 subsample has been validated and characterized with this technique. Sixty-Two SZ sources (54% of this PSZ1 subset) remain unconfirmed. In addition, we find that the fraction of unconfirmed clusters close to the galactic plane (at |b| < 25°) is greater than that at higher galactic latitudes (|b| > 25°), which indicates contamination produced by radio emission of galactic dust and gas clouds on these SZ detections. In fact, in the majority of the cases, we detect important galactic cirrus in the optical images, mainly in the SZ target located at low galactic latitudes, which supports this hypothesis. © ESO 2018.