Herschel-SPIRE observations of the Polaris flare : structure of the diffuse interstellar medium at the sub-parsec scale

M. -A. Miville-Deschênes (1) , P. G. Martin (2) , A. Abergel (1) , J. -P. Bernard , F. Boulanger (1) , Guilaine Lagache (1) , L. D. Anderson (3) , P. André (4) , H. Arab , J. -P. Baluteau (3) , K. Blagrave , Sylvain Bontemps (5, 6, 7, 8) , M. Cohen , M. Compiegne , P. Cox , E. Dartois (1) , G. Davis (9) , R. Emery , T. Fulton , C. Gry (3) , E. Habart (1) , M. Huang (10) , C. Joblin (11) , S. C. Jones , J. Kirk (12) , T. Lim (13) , S. Madden (14) , G. Makiwa , A. Menshchikov , S. Molinari (15) , H. Moseley , F. Motte (16, 17) , D. A. Naylor , K. Okumura , D. Pinheiro Gocalvez , E. Polehampton , J. A. Rodón , D. Russei , P. Saraceno (15) , N. Schneider (16) , S. Sidher , L. Spencer , B. Swinyard , D. Ward-Thompson (12) , G. J. White (18) , Annie Zavagno (3, 19)

1 IAS - Institut d'astrophysique spatiale
2 LM2C - Laboratoire de Modélisation Multi-échelles des Combustibles
3 LAM - Laboratoire d'Astrophysique de Marseille
4 LINA - Laboratoire d'Informatique de Nantes Atlantique
5 LAB - Laboratoire d'Astrophysique de Bordeaux [Pessac]
6 OASU - Observatoire aquitain des sciences de l'univers
7 UB - Université Sciences et Technologies - Bordeaux 1
8 L3AB - Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux
9 Department of Ecology and Evolutionary Biology [Princeton]
10 NAOC - National Astronomical Observatories [Beijing]
11 CESR - Centre d'étude spatiale des rayonnements
12 School of Physics and Astronomy [Cardiff]
13 LPMA - Laboratoire de Probabilités et Modèles Aléatoires
14 DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
15 IFSI - Istituto di Fisica dello Spazio Interplanetario
16 AIM (UMR7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation
17 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
18 Engineering Department
19 OAMP - Observatoire Astronomique de Marseille Provence

We present a power spectrum analysis of the Herschel-SPIRE observations of the Polaris flare, a high Galactic latitude cirrus cloud midway between the diffuse and molecular phases. The SPIRE images of the Polaris flare reveal for the first time the structure of the diffuse interstellar medium down to 0.01 parsec over a 10 square degrees region. These exceptional observations highlight the highly filamentary and clumpy structure of the interstellar medium even in diffuse regions of the map. The power spectrum analysis shows that the structure of the interstellar medium is well described by a single power law with an exponent of -2.7 +- 0.1 at all scales from 30" to 8 degrees. That the power spectrum slope of the dust emission is constant down to the SPIRE angular resolution is an indication that the inertial range of turbulence extends down to the 0.01 pc scale. The power spectrum analysis also allows the identification of a Poissonian component at sub-arcminute scales in agreement with predictions of the cosmic infrared background level at SPIRE wavelengths. Finally, the comparison of the SPIRE and IRAS 100 micron data of the Polaris flare clearly assesses the capability of SPIRE in maping diffuse emission over large areas.

Domaines: Astrophysique stellaire et solaire [astro-ph.SR]; Astrophysique stellaire et solaire [astro-ph.SR]

M. -A. Miville-Deschênes, P. G. Martin, A. Abergel, J. -P. Bernard, F. Boulanger, et al.. Herschel-SPIRE observations of the Polaris flare : structure of the diffuse interstellar medium at the sub-parsec scale. Astronomy and Astrophysics - A&A, 2010, 518, pp.L104. ⟨10.1051/0004-6361/201014678⟩. ⟨hal-00523050⟩