Ade, P.A.R. and Aghanim, N. and Alves, M.I.R. and Arnaud, M. and Ashdown, M. and Atrio-Barandela, F. and Aumont, J. and Baccigalupi, C. and Banday, A.J. and Barreiro, R.B. and Bartlett, J.G. and Battaner, E. and Benabed, K. and Benoit-Lévy, A. and Bernard, J.-P. and Bersanelli, M. and Bielewicz, P. and Bobin, 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 Butler, R.C. and Cardoso, J.-F. and Catalano, A. and Chamballu, A. and Chiang, H.C. and Chiang, L.-Y. and Christensen, P.R. and Clements, D.L. and Colombi, S. and Colombo, L.P.L. and Couchot, F. and Crill, B.P. and Curto, A. and Cuttaia, F. and Danese, L. and Davies, R.D. and Davis, R.J. and De Bernardis, P. and de Rosa, A. and de Zotti, G. and Delabrouille, J. and Dickinson, C. and Diego, J.M. and Dole, H. and Donzelli, S. and Dore, O. and Douspis, M. and Dupac, X. and Enßlin, T.A. and Eriksen, H.K. and Falgarone, E. and Finelli, F. and Forni, O. and Frailis, M. and Franceschi, E. and Galeotta, S. and Ganga, K. and Ghosh, T. and Giard, M. and Giardino, G. and Gonzalez-Nuevo, J. and Gorski, K.M. and Gregorio, A. and Gruppuso, A. and Hansen, F.K. and Harrison, D. and Hernandez-Monteagudo, C. and Herranz, D. and Hildebrandt, S.R. and Hivon, E. and Holmes, W.A. and Hornstrup, A. and Hovest, W. and Jaffe, A.H. and Jones, W.C. and Juvela, M. and Keihanen, E. and Keskitalo, R. and Kisner, T.S. and Kneissl, R. and Knoche, J. and Kunz, M. and Kurki-Suonio, H. and Lagache, G. and Lahteenmaki, A. and Lamarre, J.-M. and Lasenby, A. and Laureijs, R.J. and Lawrence, C.R. and Leonardi, R. and Levrier, F. and Liguori, M. and Lilje, P.B. and Linden-Vornle, M. and Lopez-Caniego, M. and Macias-Perez, J.F. and Maffei, B. and Maino, D. and Mandolesi, N. and Maris, M. and Marshall, D.J. and Martin, P.G. and Martinez-Gonzalez, E. and Masi, S. and Matarrese, S. and Mazzotta, P. and Melchiorri, A. and Mendes, L. and Mennella, A. and Migliaccio, M. and Mitra, S. 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 Norgaard-Nielsen, H.U. and Noviello, F. and Novikov, D. and Novikov, I. and Oxborrow, C.A. and Pagano, L. and Pajot, F. and Paladini, R. and Paoletti, D. and Pasian, F. and Patanchon, G. and Peel, M. and Perdereau, O. and Perrotta, F. and Piacentini, F. and Piat, M. and Pierpaoli, E. and Pietrobon, D. and Plaszczynski, S. and Pointecouteau, E. and Polenta, G. and Ponthieu, N. and Popa, L. and Pratt, G.W. and Prunet, S. and Puget, J.-L. and Rachen, J.P. and Reach, W.T. and Rebolo, R. and Reinecke, M. and Remazeilles, M. and Renault, C. and Ricciardi, S. and Riller, T. and Ristorcelli, I. and Rocha, G. and Rosset, C. and Rubino-Martin, J.A. and Rusholme, B. and Sandri, M. and Savini, G. and Scott, D. and Spencer, L. and Starck, J.-L. and Stolyarov, V. and Sureau, F. and Sutton, D. and Suur-Uski, A.-S. and Sygnet, J.-F. and Tauber, J.A. and Tavagnacco, D. and Terenzi, L. and Toffolatti, L. and Tomasi, M. and Tristram, M. and Tucci, M. and Valenziano, L. and Valiviita, J. and Van Tent, B. and Verstraete, L. and Vielva, P. and Villa, F. and Vittorio, N. and Wade, L.A. and Wandelt, B.D. and Yvon, D. and Zacchei, A. and Zonca, A. (2014) Planck intermediate results. XIV. Dust emission at millimetre wavelengths in the Galactic plane. Astronomy & Astrophysics, 564 (A45). ISSN 0004-6361

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Abstract

We use Planck HFI data combined with ancillary radio data to study the emissivity index of the interstellar dust emission in the frequency range 100–353 GHz, or 3–0.8 mm, in the Galactic plane. We analyse the region l = 20°–44° and |b| ≤ 4° where the free-free emission can be estimated from radio recombination line data. We fit the spectra at each sky pixel with a modified blackbody model and two opacity spectral indices, βmm and βFIR, below and above 353 GHz, respectively. We find that βmm is smaller than βFIR, and we detect a correlation between this low frequency power-law index and the dust optical depth at 353 GHz, τ353. The opacity spectral index βmm increases from about 1.54 in the more diffuse regions of the Galactic disk, |b| = 3°–4° and τ353 ~ 5 × 10-5, to about 1.66 in the densest regions with an optical depth of more than one order of magnitude higher. We associate this correlation with an evolution of the dust emissivity related to the fraction of molecular gas along the line of sight. This translates into βmm ~ 1.54 for a medium that is mostly atomic and βmm ~ 1.66 when the medium is dominated by molecular gas. We find that both the two-level system model and magnetic dipole emission by ferromagnetic particles can explain the results. These results improve our understanding of the physics of interstellar dust and lead towards a complete model of the dust spectrum of the Milky Way from far-infrared to millimetre wavelengths.

Item Type:	Article
Keywords:	Planck Collaboration; ISM: general; Galaxy: general; radiation mechanisms: general; radio continuum: ISM; submillimeter: ISM;
Academic Unit:	Faculty of Science and Engineering > Experimental Physics
Item ID:	14130
Identification Number:	https://doi.org/10.1051/0004-6361/201322367
Depositing User:	Dr. Anthony Murphy
Date Deposited:	04 Mar 2021 14:43
Journal or Publication Title:	Astronomy & Astrophysics
Publisher:	EDP Sciences
Refereed:	Yes
URI:	Publisher
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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