Evidence for Environmental Changes in the Submillimeter Dust Opacity - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue The Astrophysical Journal Année : 2012

Evidence for Environmental Changes in the Submillimeter Dust Opacity

Peter G. Martin
  • Fonction : Auteur
Arnaud Roy
  • Fonction : Auteur
Sylvain Bontemps
Marc-Antoine Miville-Deschênes
Peter A. R. Ade
  • Fonction : Auteur
James J. Bock
  • Fonction : Auteur
Edward L. Chapin
  • Fonction : Auteur
Mark J. Devlin
  • Fonction : Auteur
Simon R. Dicker
  • Fonction : Auteur
Matthew Griffin
  • Fonction : Auteur
Joshua O. Gundersen
  • Fonction : Auteur
Mark Halpern
  • Fonction : Auteur
Peter C. Hargrave
  • Fonction : Auteur
David H. Hughes
  • Fonction : Auteur
Jeff Klein
  • Fonction : Auteur
Gaelen Marsden
  • Fonction : Auteur
Philip Mauskopf
  • Fonction : Auteur
Calvin B. Netterfield
  • Fonction : Auteur
Luca Olmi
  • Fonction : Auteur
G. Patanchon
  • Fonction : Auteur
Marie Rex
  • Fonction : Auteur
Douglas Scott
Christopher Semisch
  • Fonction : Auteur
Matthew D. P. Truch
  • Fonction : Auteur
Carole Tucker
  • Fonction : Auteur
Gregory S. Tucker
  • Fonction : Auteur
Marco P. Viero
  • Fonction : Auteur
Donald V. Wiebe
  • Fonction : Auteur

Résumé

The submillimeter opacity of dust in the diffuse Galactic interstellar medium (ISM) has been quantified using a pixel-by-pixel correlation of images of continuum emission with a proxy for column density. We used three BLAST bands at 250, 350, and 500 \mu m and one IRAS at 100 \mu m. The proxy is the near-infrared color excess, E(J-Ks), obtained from 2MASS. Based on observations of stars, we show how well this color excess is correlated with the total hydrogen column density for regions of moderate extinction. The ratio of emission to column density, the emissivity, is then known from the correlations, as a function of frequency. The spectral distribution of this emissivity can be fit by a modified blackbody, whence the characteristic dust temperature T and the desired opacity \sigma_e(1200) at 1200 GHz can be obtained. We have analyzed 14 regions near the Galactic plane toward the Vela molecular cloud, mostly selected to avoid regions of high column density (N_H > 10^{22} cm^-2) and small enough to ensure a uniform T. We find \sigma_e(1200) is typically 2 to 4 x 10^{-25} cm^2/H and thus about 2 to 4 times larger than the average value in the local high Galactic latitude diffuse atomic ISM. This is strong evidence for grain evolution. There is a range in total power per H nucleon absorbed (re-radiated) by the dust, reflecting changes in the interstellar radiation field and/or the dust absorption opacity. These changes affect the equilibrium T, which is typically 15 K, colder than at high latitudes. Our analysis extends, to higher opacity and lower T, the trend of increasing opacity with decreasing T that was found at high latitudes. The recognition of changes in the emission opacity raises a cautionary flag because all column densities deduced from dust emission maps, and the masses of compact structures within them, depend inversely on the value adopted.

Dates et versions

hal-00664696 , version 1 (31-01-2012)

Identifiants

Citer

Peter G. Martin, Arnaud Roy, Sylvain Bontemps, Marc-Antoine Miville-Deschênes, Peter A. R. Ade, et al.. Evidence for Environmental Changes in the Submillimeter Dust Opacity. The Astrophysical Journal, 2012, 751, pp.28. ⟨10.1088/0004-637X/751/1/28⟩. ⟨hal-00664696⟩
176 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More