Planck Early Results: Thermal dust in Nearby Molecular Clouds
Abstract
Planck allows unbiased mapping of Galactic sub-millimetre and millimetre emission from the most diffuse regions to the densest parts of molecular clouds. We present an early analysis of the Taurus molecular complex, on line-of-sight-averaged data and without component separation. The emission spectrum measured by Planck and IRAS can be fitted pixel by pixel using a single modified blackbody. Some systematic residuals are detected at 353 GHz and 143 GHz, with amplitudes around -7 % and +13 %, respectively, indicating that the measured spectra are likely more complex than a simple modified blackbody. Significant positive residuals are also detected in the molecular regions and in the 217 GHz and 100 GHz bands, mainly caused by to the contribution of the J=2-1 and J=1-0 12CO and 13CO emission lines. We derive maps of the dust temperature T, the dust spectral emissivity index beta, and the dust optical depth at 250 microns tau. The temperature map illustrates the cooling of the dust particles in thermal equilibrium with the incident radiation field, from 16-17 K in the diffuse regions to 13-14 K in the dense parts. The distribution of spectral indices is centred at 1.78, with a standard deviation of 0.08 and a systematic error of 0.07. We detect a significant T-beta anti-correlation. The dust optical depth map reveals the spatial distribution of the column density of the molecular complex from the densest molecular regions to the faint diffuse regions. We use near-infrared extinction and HI data at 21-cm to perform a quantitative analysis of the spatial variations of the measured dust optical depth at 250 microns per hydrogen atom tau/NH. We report an increase of tau/NH by a factor of about 2 between the atomic phase and the molecular phase, which has a strong impact on the equilibrium temperature of the dust particles.
Keywords
Cite
@article{arxiv.1101.2037,
title = {Planck Early Results: Thermal dust in Nearby Molecular Clouds},
author = {Planck Collaboration and A. Abergel and P. A. R. Ade and N. Aghanim and M. Arnaud and M. Ashdown and J. Aumont and C. Baccigalupi and A. Balbi and A. J. Banday and R. B. Barreiro and J. G. Bartlett and E. Battaner and K. Benabed and A. Benoît and J. -P. Bernard and M. Bersanelli and R. Bhatia and J. J. Bock and A. Bonaldi and J. R. Bond and J. Borrill and F. R. Bouchet and F. Boulanger and M. Bucher and C. Burigana and P. Cabella and J. -F. Cardoso and A. Catalano and L. Cayón and A. Challinor and A. Chamballu and L. -Y Chiang and C. Chiang and P. R. Christensen and D. L. Clements and S. Colombi and F. Couchot and A. Coulais and B. P. Crill and F. Cuttaia and L. Danese and R. D. Davies and R. J. Davis and P. de Bernardis and G. de Gasperis and A. de Rosa and G. de Zotti and J. Delabrouille and J. -M. Delouis and F. -X. Désert and C. Dickinson and K. Dobashi and S. Donzelli and O. Doré and U. Dörl and M. Douspis and X. Dupac and G. Efstathiou and T. A. Enßlin and H. K. Eriksen and F. Finelli and O. Forni and M. Frailis and E. Franceschi and S. Galeotta and K. Ganga and M. Giard and G. Giardino and Y. Giraud-Héraud and J. González-Nuevo and K. M. Górski and S. Gratton and A. Gregorio and A. Gruppuso and V. Guillet and F. K. Hansen and D. Harrison and S. Henrot-Versillé and D. Herranz and S. R. Hildebrandt and E. Hivon and M. Hobson and W. A. Holmes and W. Hovest and R. J. Hoyland and K. M. Huffenberger and A. H. Jaffe and A. Jones and W. C. Jones and M. Juvela and E. Keihänen and R. Keskitalo and T. S. Kisner and R. Kneissl and L. Knox and H. Kurki-Suonio and G. Lagache and J. -M. Lamarre and A. Lasenby and R. J. Laureijs and C. R. Lawrence and S. Leach and R. Leonardi and C. Leroy and M. Linden-Vørnle and M. López-Caniego and P. M. Lubin and J. F. Macías-Pérez and C. J. MacTavish and B. Maffei and N. Mandolesi and R. Mann and M. Maris and D. J. Marshall and P. Martin and E. Martínez-González and S. Masi and S. Matarrese and F. Matthai and P. Mazzotta and P. McGehee and P. R. Meinhold and A. Melchiorri and L. Mendes and A. Mennella and S. Mitra and M. -A. Miville-Deschênes and A. Moneti and L. Montier and G. Morgante and D. Mortlock and D. Munshi and A. Murphy and P. Naselsky and P. Natoli and C. B. Netterfield and H. U. Nørgaard-Nielsen and F. Noviello and D. Novikov and I. Novikov and S. Osborne and F. Pajot and R. Paladini and F. Pasian and G. Patanchon and O. Perdereau and L. Perotto and F. Perrotta and F. Piacentini and M. Piat and S. Plaszczynski and E. Pointecouteau and G. Polenta and N. Ponthieu and T. Poutanen and G. Prézeau and S. Prunet and J. -L. Puget and W. T. Reach and R. Rebolo and M. Reinecke and C. Renault and S. Ricciardi and T. Riller and I. Ristorcelli and G. Rocha and C. Rosset and J. A. Rubiño-Martín and B. Rusholme and M. Sandri and D. Santos and G. Savini and D. Scott and M. D. Seiffert and P. Shellard and G. F. Smoot and J. -L. Starck and F. Stivoli and V. Stolyarov and R. Sudiwala and J. -F. Sygnet and J. A. Tauber and L. Terenzi and L. Toffolatti and M. Tomasi and J. -P. Torre and M. Tristram and J. Tuovinen and G. Umana and L. Valenziano and L. Verstraete and P. Vielva and F. Villa and N. Vittorio and L. A. Wade and B. D. Wandelt and D. Yvon and A. Zacchei and A. Zonca},
journal= {arXiv preprint arXiv:1101.2037},
year = {2015}
}
Comments
Planck early paper accepted for publication in Astronomy & Astrophysics, 18 pages