Site Map
Contacts
Follow us on Facebook Follow us on Twitter YouTube channel
Centro de Astrofísica da Universidade do Porto

Planck intermediate results
VIII. Filaments between interacting clusters

P. A. R. Ade, N. Aghanim, M. Arnaud, M. Ashdown, F. Atrio-Barandela, J. Aumont, C. Baccigalupi, A. Balbi, A. J. Banday, R. B. Barreiro, J.G. Bartlett, E. Battaner, K. Benabed, A. Benoît, J.-P. Bernard, M. Bersanelli, R. Bhatia, I. Bikmaev, H. Böhringer, A. Bonaldi, J. R. Bond, J. Borrill, F. R. Bouchet, H. Bourdin, R. Burenin, C. Burigana, P. Cabella, J.-F. Cardoso, G. Castex, A. Catalano, L. Cayón, A. Chamballu, R.-R. Chary, L.-Y. Chiang, G. Chon, P. R. Christensen, D. L. Clements, S. Colafrancesco, L. P. L. Colombo, B. Comis, A. Coulais, B. P. Crill, F. Cuttaia, A. C. da Silva, H. Dahle, L. Danese, R. J. Davis, P. de Bernardis, G. de Gasperis, G. de Zotti, J. Delabrouille, J. Démoclès, F.-X. Désert, J. M. Diego, K. Dolag, H. Dole, S. Donzelli, O. Doré, U. Dörl, M. Douspis, X. Dupac, G. Efstathiou, T. A. Enβlin, H. K. Eriksen, F. Finelli, I. Flores-Cacho, O. Forni, M. Frailis, E. Franceschi, M. Frommert, S. Galeotta, K. Ganga, R. T. Génova-Santos, M. Giard, M. Gilfanov, Y. Giraud-Héraud, J. González-Nuevo, K. Górski, A. Gregorio, A. Gruppuso, F. K. Hansen, D. L. Harrison, A. Hempel, S. Henrot-Versillé, C. Hernández-Monteagudo, D. Herranz, S. R. Hildebrandt, E. Hivon, M. Hobson, W. A. Holmes, W. Hovest, G. Hurier, T. R. Jaffe, A. H. Jaffe, T. Jagemann, W. C. Jones, M. Juvela, I. Khamitov, T. S. Kisner, R. Kneissl, J. Knoche, L. Knox, M. Kunz, H. Kurki-Suonio, G. Lagache, J.-M. Lamarre, A. Lasenby, C. R. Lawrence, M. Le Jeune, R. Leonardi, P. B. Lilje, M. Linden-Vørnle, M. López-Caniego, P. M. Lubin, G. Luzzi, J. F. Macías-Pérez, B. Maffei, D. Maino, N. Mandolesi, M. Maris, F. Marleau, D. J. Marshall, E. Martínez-González, S. Masi, M. Massardi, S. Matarrese, F. Matthai, P. Mazzotta, S. Mei, A. Melchiorri, J.-B. Melin, L. Mendes, A. Mennella, S. Mitra, M.-A. Miville-Deschênes, A. Moneti, L. Montier, G. Morgante, D. Munshi, J. A. Murphy, P. Naselsky, F. Nati, P. Natoli, H. U. Nørgaard-Nielsen, F. Noviello, D. Novikov, I. Novikov, S. Osborne, F. Pajot, D. Paoletti, F. Pasian, G. Patanchon, O. Perdereau, L. Perotto, F. Perrotta, F. Piacentini, M. Piat, E. Pierpaoli, R. Piffaretti, S. Plaszczynski, E. Pointecouteau, G. Polenta, N. Ponthieu, L. Popa, T. Poutanen, G. W. Pratt, S. Prunet, J.-L. Puget, J. P. Rachen, R. Rebolo López, M. Reinecke, M. Remazeilles, C. Renault, S. Ricciardi, T. Riller, I. Ristorcelli, G. Rocha, M. Roman, C. Rosset, M. Rossetti, J. A. Rubiño-Martin, B. Rusholme, M. Sandri, G. Savini, B. M. Schäfer, D. Scott, G. F. Smoot, J.-L. Starck, R. Sudiwala, R. Sunyaev, D. Sutton, A.-S. Suur-Uski, J.-F. Sygnet, J. A. Tauber, L. Terenzi, L. Toffolatti, M. Tomasi, M. Tristram, L. Valenziano, B. Van Tent, P. Vielva, F. Villa, N. Vittorio, L. A. Wade, B. D. Wandelt, N Welikala, S. D. M. White, D. Yvon, A. Zacchei, A. Zonca

Abstract
Context. About half of the baryons of the Universe are expected to be in the form of filaments of hot and low-density intergalactic medium. Most of these baryons remain undetected even by the most advanced X-ray observatories, which are limited in sensitivity to the diffuse low-density medium.
Aims. The Planck satellite has provided hundreds of detections of the hot gas in clusters of galaxies via the thermal Sunyaev-Zel’dovich (tSZ) effect and is an ideal instrument for studying extended low-density media through the tSZ effect. In this paper we use the Planck data to search for signatures of a fraction of these missing baryons between pairs of galaxy clusters.
Methods. Cluster pairs are good candidates for searching for the hotter and denser phase of the intergalactic medium (which is more easily observed through the SZ effect). Using an X-ray catalogue of clusters and the Planck data, we selected physical pairs of clusters as candidates. Using the Planck data, we constructed a local map of the tSZ effect centred on each pair of galaxy clusters. ROSAT data were used to construct X-ray maps of these pairs. After modelling and subtracting the tSZ effect and X-ray emission for each cluster in the pair, we studied the residuals on both the SZ and X-ray maps.
Results. For the merging cluster pair A399-A401 we observe a significant tSZ effect signal in the intercluster region beyond the virial radii of the clusters. A joint X-ray SZ analysis allows us to constrain the temperature and density of this intercluster medium. We obtain a temperature of kT = 7.1 ± 0.9 keV (consistent with previous estimates) and a baryon density of (3.7 ± 0.2) × 10-4 cm-3.
Conclusions. The Planck satellite mission has provided the first SZ detection of the hot and diffuse intercluster gas.

Keywords
galaxies: clusters: general – large-scale structure of Universe

Astronomy and Astrophysics
Volume 550, Page A134_1
February 2013

>> PDF>> ADS>> DOI

Institute of Astrophysics and Space Sciences

Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

Proceed on CAUP's website|Go to IA website