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    Planck intermediate results XXIII. Galactic plane emission components derived from Planck with ancillary data

    Ade, P.A.R. and Aghanim, N. and Alves, M.I.R. and Arnaud, Martha B. and Ashdown, M. and Atrio-Barandela, F. and Aumont, J. and Baccigalupi, C. and Banday, A.J. and Barreiro, R.B. 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 Bouchet, F.R. and Boulanger, F. and Burigana, C. and Cardoso, J.-F. and Catalano, A. and Chamballu, A. and Chiang, H.C. and Christensen, P.R. and Clements, D.L. and Colombi, S. and Colombo, L.P.L. and Combet, C. and Couchot, F. and Crill, B.P. 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 Donzelli, S. and Dore, O. 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 Genova-Santos, R.T. and Ghosh, T. and Giard, M. and Giardino, G. and Giraud-Héraud, Y. and Gonzalez-Nuevo, J. and Gorski, K.M. and Gregorio, A. and Gruppuso, A. and Hansen, F.K. and Harrison, D. and Henrot-Versille, S. and Herranz, D. and Hildebrandt, S.R. and Hivon, E. and Hobson, M. and Hornstrup, A. and Hovest, W. and Huffenberger, K.M. and Jaffe, A.H. and Jaffe, T.R. and Jones, W.C. 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 Lawrence, C.R. and Leonardi, R. and Liguori, M. and Lilje, P.B. and Linden-Vornle, M. and Lopez-Caniego, M. and Lubin, P.M. and Macias-Perez, J.F. and Maino, D. and Mandolesi, N. and Martin, P.G. and Martinez-Gonzalez, E. and Masi, S. and Massardi, M. and Matarrese, S. and Mazzotta, P. and Meinhold, P.R. 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 Pearson, T.J. 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 Reich, W. 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 Roudier, G. and Rubino-Martin, J.A. and Rusholme, B. and Sandri, M. and Savini, G. and Scott, D. and Spencer, L. and Stolyarov, V. and Strong, A.W. and Sutton, D. and Suur-Uski, A.-S. and Sygnet, J.-F. and Tauber, J.A. and Tavagnacco, D. and Terenzi, L. and Tibbs, C.T. and Toffolatti, L. and Tomasi, M. and Tristram, M. and Tucci, M. and Valenziano, L. and Valiviita, J. and Van Tent, B. and Varis, J. and Vielva, P. and Villa, F. and Wade, L.A. and Wandelt, B.D. and Watson, R. and Yvon, D. and Zacchei, A. and Zonca, A. (2015) Planck intermediate results XXIII. Galactic plane emission components derived from Planck with ancillary data. Astronomy & Astrophysics, 580 (A13). ISSN 0004-6361

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    Planck data when combined with ancillary data provide a unique opportunity to separate the diffuse emission components of the inner Galaxy. The purpose of the paper is to elucidate the morphology of the various emission components in the strong star-formation region lying inside the solar radius and to clarify the relationship between the various components. The region of the Galactic plane covered is l = 300° → 0° → 60° wherestar-formation is highest and the emission is strong enough to make meaningful component separation. The latitude widths in this longitude range lie between 1° and 2°, which correspond to FWHM z-widths of 100−200 pc at a typical distance of 6 kpc. The four emission components studied here are synchrotron, free-free, anomalous microwave emission (AME), and thermal (vibrational) dust emission. These components are identified by constructing spectral energy distributions (SEDs) at positions along the Galactic plane using the wide frequency coverage of Planck (28.4−857 GHz) in combination with low-frequency radio data at 0.408−2.3 GHz plus WMAP data at 23−94 GHz, along with far-infrared (FIR) data from COBE-DIRBE and IRAS. The free-free component is determined from radio recombination line (RRL) data. AME is found to be comparable in brightness to the free-free emission on the Galactic plane in the frequency range 20−40 GHz with a width in latitude similar to that of the thermal dust; it comprises 45 ± 1% of the total 28.4 GHz emission in the longitude range l = 300° → 0° → 60°. The free-free component is the narrowest, reflecting the fact that it is produced by current star-formation as traced by the narrow distribution of OB stars. It is the dominant emission on the plane between 60 and 100 GHz. RRLs from this ionized gas are used to assess its distance, leading to a free-free z-width of FWHM ≈ 100 pc. The narrow synchrotron component has a low-frequency brightness spectral index βsynch ≈ −2.7 that is similar to the broad synchrotron component indicating that they are both populated by the cosmic ray electrons of the same spectral index. The width of this narrow synchrotron component is significantly larger than that of the other three components, suggesting that it is generated in an assembly of older supernova remnants that have expanded to sizes of order 150 pc in 3 × 105 yr; pulsars of a similar age have a similar spread in latitude. The thermal dust is identified in the SEDs with average parameters of Tdust = 20.4 ± 0.4 K, βFIR = 1.94 ± 0.03 (> 353 GHz), and βmm = 1.67 ± 0.02 (< 353 GHz). The latitude distributions of gamma-rays, CO, and the emission in high-frequency Planck bands have similar widths, showing that they are all indicators of the total gaseous matter on the plane in the inner Galaxy.

    Item Type: Article
    Additional Information: Appendices are available in electronic form at
    Keywords: Planck Collaboration; ISM: general; Galaxy: general; radiation mechanisms: general; radio continuum: ISM; submillimeter: ISM; Galaxy: disk;
    Academic Unit: Faculty of Science and Engineering > Experimental Physics
    Item ID: 14037
    Identification Number:
    Depositing User: Dr. Anthony Murphy
    Date Deposited: 19 Feb 2021 09:50
    Journal or Publication Title: Astronomy & Astrophysics
    Publisher: EDP Sciences
    Refereed: Yes

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