Abergel, A. and Ade, P.A.R. and Aghanim, N. and Arnaud, M. and Ashdown, M. and Aumont, J. and Baccigalupi, C. and Balbi, A. and Banday, A.J. and Barreiro, R.B. and Bartlett, J.G. and Battaner, E. and Benabed, K. and Benoit, A. and Bernard, J.-P. and Bersanelli, M. and Bhatia, R. and Blagrave, K. and Bock, J.J. and Bonaldi, A. and Bond, J.R. and Borrill, J. and Bouchet, F.R. and Boulanger, F. and Bucher, M. and Burigana, C. and Cabella, P. and Cantalupo, C.M. and Cardoso, J.-F. and Catalano, A. and Cayon, L. and Challinor, A. and Chamballu, A. and Chiang, L.-Y. and Chiang, C. and Christensen, P.R. and Clements, D.L. and Colombi, S. and Couchot, F. and Coulais, A. and Crill, B.P. and Cuttaia, F. and Danese, L. and Davies, R.D. and Davis, R.J. and De Bernardis, P. and de Gasperis, G. and de Rosa, A. and de Zotti, G. and Delabrouille, J. and Delouis, J.-M. and Desert, F.-X. and Dickinson, C. and Donzelli, S. and Dore, O. and Dorl, U. and Douspis, M. and Dupac, X. and Efstathiou, G. and Enßlin, T.A. and Eriksen, H.K. and Finelli, F. and Forni, O. and Frailis, M. and Franceschi, E. and Galeotta, S. and Ganga, K. and Giard, M. and Giardino, G. and Giraud-Héraud, Y. and Gonzalez-Nuevo, J. and Gorski, K.M. and Gratton, S. and Gregorio, A. and Grupposo, A. and Hansen, F.K. and Harrison, D. and Helou, G. and Henrot-Versille, S. and Herranz, D. and Hildebrandt, S.R. and Hivon, E. and Hobson, M. and Holmes, W.A. and Hovest, W. and Hoyland, R.J. and Huffenberger, K.M. and Jaffe, A.H. and Joncas, G. and Jones, A. and Jones, W.C. and Juvela, M. and Keihanen, E. and Keskitalo, R. and Kisner, T.S. and Kneissl, R. and Knox, L. and Kurki-Suonio, H. and Lagache, G. and Lamarre, J.-M. and Lasenby, A. and Laureijs, R.J. and Lawrence, C.R. and Leach, S. and Leonardi, R. and Leroy, C. and Linden-Vornle, M. and Lockman, F.J. and Lopez-Caniego, M. and Lubin, P.M. and Macias-Perez, J.F. and MacTavish, C.J. and Maffei, B. and Maino, D. and Mandolesi, N. and Mann, R. and Maris, M. and Marshall, D.J. and Martin, P. and Martinez-Gonzalez, E. and Masi, S. and Matarrese, S. and Matthai, F. and Mazzotta, P. and McGehee, P. and Meinhold, P.R. and Melchiorri, A. and Mendes, L. and Mennella, A. and Miville-Deschenes, M.-A. and Moneti, A. and Montier, L. and Morgante, G. and Mortlock, D. and Munshi, D. and Murphy, J.Anthony and Naselsky, P. and Nati, F. and Natoli, P. and Netterfield, C.B. and Norgaard-Nielsen, H.U. and Noviello, F. and Novikov, D. and Novikov, I. and O'Dwyer, I.J. and Osborne, S. and Pajot, F. and Paladini, R. and Pasian, F. and Patanchon, G. and Perdereau, O. and Perotto, L. and Perrotta, F. and Piacentini, F. and Piat, M. and Pinheiro Goncalves, D. and Plaszczynski, S. and Pointecouteau, E. and Polenta, G. and Ponthieu, N. and Poutanen, T. and Prezeau, G. and Prunet, S. and Puget, J.-L. and Rachen, J.P. and Reach, W.T. and Reinecke, M. and Renault, C. and Ricciardi, S. and Riller, T. and Ristorcelli, I. and Rocha, G. and Rosset, C. and Rowan-Robinson, M. and Rubino-Martin, J.A. and Rusholme, B. and Sandri, M. and Santos, D. and Savini, G. and Scott, D. and Seiffert, M.D. and Shellard, P. and Smoot, G.F. and Starck, J.-L. and Stivoli, F. and Stolyarov, V. and Stompor, R. and Sudiwala, R. and Sygnet, J.-F. and Tauber, J.A. and Terenzi, L. and Toffolatti, L. and Tomasi, M. and Torre, J.-P. and Tristram, M. and Tuovinen, J. and Umana, G. and Valenziano, L. and Vielva, P. and Villa, F. and Vittorio, N. and Wade, L.A. and Wandelt, B.D. and Wilkinson, A. and Yvon, D. and Zacchei, A. and Zonca, A. (2011) Planck early results. XXIV. Dust in the diffuse interstellar medium and the Galactic halo. Astronomy & Astrophysics, 536 (A24). pp. 1-30. ISSN 0004-6361

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Abstract

This paper presents the first results from a comparison of Planck dust maps at 353, 545 and 857 GHz, along with IRAS data at 3000 (100 μm) and 5000 GHz (60 μm), with Green Bank Telescope 21-cm observations of Hi in 14 fields covering more than 800 deg2 at high Galactic latitude. The main goal of this study is to estimate the far-infrared to sub-millimeter (submm) emissivity of dust in the diffuse local interstellar medium (ISM) and in the intermediate-velocity (IVC) and high-velocity clouds (HVC) of the Galactic halo. Galactic dust emission for fields with average Hi column density lower than 2 × 1020 cm−2 is well correlated with 21-cm emission because in such diffuse areas the hydrogen is predominantly in the neutral atomic phase. The residual emission in these fields, once the Hi-correlated emission is removed, is consistent with the expected statistical properties of the cosmic infrared background fluctuations. The brighter fields in our sample, with an average Hi column density greater than 2 × 1020 cm−2, show significant excess dust emission compared to the Hi column density. Regions of excess lie in organized structures that suggest the presence of hydrogen in molecular form, though they are not always correlated with CO emission. In the higher Hi column density fields the excess emission at 857 GHz is about 40% of that coming from the Hi, but over all the high latitude fields surveyed the molecular mass faction is about 10%. Dust emission from IVCs is detected with high significance by this correlation analysis. Its spectral properties are consistent with, compared to the local ISM values, significantly hotter dust (T ∼ 20K), lower submm dust opacity normalized per H-atom, and a relative abundance of very small grains to large grains about four times higher. These results are compatible with expectations for clouds that are part of the Galactic fountain in which there is dust shattering and fragmentation. Correlated dust emission in HVCs is not detected; the average of the 99.9% confidence upper limits to the emissivity is 0.15 times the local ISM value at 857 and 3000 GHz, in accordance with gas phase evidence for lower metallicity and depletion in these clouds. Unexpected anti-correlated variations of the dust temperature and emission cross-section per H atom are identified in the local ISM and IVCs, a trend that continues into molecular environments. This suggests that dust growth through aggregation, seen in molecular clouds, is active much earlier in the cloud condensation and star formation processes.

Item Type:	Article
Additional Information:	© ESO 2011 The original publication is available at DOI: 10.1051/0004-6361/201116485
Keywords:	infrared; ISM – methods; data analysis; dust; extinction; submillimeter; Galaxy; halo; local insterstellar matter; Planck Collaboration;
Academic Unit:	Faculty of Science and Engineering > Experimental Physics
Item ID:	4047
Depositing User:	Dr. Anthony Murphy
Date Deposited:	19 Dec 2012 17:15
Journal or Publication Title:	Astronomy & Astrophysics
Publisher:	EDP Sciences
Refereed:	Yes
URI:	http://www.aanda.org/ http://publications.edpsciences.org/
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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