Bibcode
Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Balbi, A.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Battaner, E.; Benabed, K.; Benoît, A.; Bernard, J.-P.; Bersanelli, M.; Bikmaev, I.; Böhringer, H.; Bonaldi, A.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Bourdin, H.; Brown, M. L.; Brown, S. D.; Burenin, R.; Burigana, C.; Cabella, P.; Cardoso, J.-F.; Carvalho, P.; Catalano, A.; Cayón, L.; Chiang, L.-Y.; Chon, G.; Christensen, P. R.; Churazov, E.; Clements, D. L.; Colafrancesco, S.; Colombo, L. P. L.; Coulais, A.; Crill, B. P.; Cuttaia, F.; Da Silva, A.; Dahle, H.; Danese, L.; Davis, R. J.; de Bernardis, P.; de Gasperis, G.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Démoclès, J.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Dolag, K.; Dole, H.; Donzelli, S.; Doré, O.; Dörl, U.; Douspis, M.; Dupac, X.; Enßlin, T. A.; Eriksen, H. K.; Finelli, F.; Flores-Cacho, I.; Forni, O.; Frailis, M.; Franceschi, E.; Frommert, M.; Galeotta, S.; Ganga, K.; Génova-Santos, R. T.; Giard, M.; Gilfanov, M.; González-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Harrison, D.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, T. R.; Jagemann, T.; Jones, W. C.; Juvela, M.; Keihänen, E.; Khamitov, I.; Kneissl, R.; Knoche, J. et al.
Bibliographical reference
Astronomy and Astrophysics, Volume 554, id.A140, 19 pp.
Advertised on:
6
2013
Journal
Citations
117
Refereed citations
107
Description
We present an analysis of Planck satellite data on the Coma cluster
observed via the Sunyaev-Zeldovich effect. Thanks to its great
sensitivity, Planck is able, for the first time, to detect SZ emission
up to r ≈ 3 × R500. We test previously proposed
spherically symmetric models for the pressure distribution in clusters
against the azimuthally averaged data. In particular, we find that the
Arnaud et al. (2010, A&A, 517, A92) "universal" pressure profile
does not fit Coma, and that their pressure profile for merging systems
provides a reasonable fit to the data only at r < R500; by
r = 2 × R500 it underestimates the observed y profile
by a factor of ≃2. This may indicate that at these larger radii
either: i) the cluster SZ emission is contaminated by unresolved SZ
sources along the line of sight; or ii) the pressure profile of Coma is
higher at r > R500 than the mean pressure profile
predicted by the simulations used to constrain the models. The Planck
image shows significant local steepening of the y profile in two regions
about half a degree to the west and to the south-east of the cluster
centre. These features are consistent with the presence of shock fronts
at these radii, and indeed the western feature was previously noticed in
the ROSAT PSPC mosaic as well as in the radio. Using Plancky profiles
extracted from corresponding sectors we find pressure jumps of
4.9-0.2+0.4 and 5.0-0.1+1.3
in the west and south-east, respectively. Assuming Rankine-Hugoniot
pressure jump conditions, we deduce that the shock waves should
propagate with Mach number Mw =
2.03-0.04+0.09 and Mse =
2.05-0.02+0.25 in the west and south-east,
respectively. Finally, we find that the y and radio-synchrotron signals
are quasi-linearly correlated on Mpc scales, with small intrinsic
scatter. This implies either that the energy density of cosmic-ray
electrons is relatively constant throughout the cluster, or that the
magnetic fields fall off much more slowly with radius than previously
thought.
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