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Dust-correlated centimetre-wave radiation from the M78 reflection nebula

Castellanos, Pablo and Casassus, Simon and Dickinson, Clive and Vidal, Matías and Paladini, Roberta and Cleary, Kieran and Davies, Rodney D. and Davis, Richard J. and White, Glenn J. and Taylor, Angela (2011) Dust-correlated centimetre-wave radiation from the M78 reflection nebula. Monthly Notices of the Royal Astronomical Society, 411 (2). pp. 1137-1150. ISSN 0035-8711.

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An anomalous radio continuum component at cm-wavelengths has been observed in various sources, including dark clouds. This continuum component represents a new property of the interstellar medium. In this work, we focus on one particular dark cloud, the bright reflection nebula M78. The main goal of this work is to investigate the cm-wave continuum emission in a prominent molecular cloud, nearby and with complementary observational data. We acquired Cosmic Background Imager (CBI) visibility data of M78 at 31 GHz with an angular resolution of ~5.8 arcmin, and CBI2 data at an angular resolution of ~4.2 arcmin. A morphological analysis was undertaken to search for possible correlations with templates that trace different emission mechanisms. Using data from Wilkinson Microwave Anisotropy Probe and the Rhodes/HartRAO 2326-MHz survey, we constructed the spectral energy distribution (SED) of M78 in a 45-arcmin circular aperture. We used results from the literature to constrain the physical conditions and the stellar content. The 5–31 GHz spectral index in flux density (α = 1.89 ± 0.15) is significantly different from optically thin free–free values. We also find closer morphological agreement with IR dust tracers than with free–free sources. Dust-correlated cm-wave emission that is not due to free–free is significant at small scales (CBI resolutions). However, a free–free background dominates at cm-wavelengths on large scales (~1°). We correct for this uniform background by differencing against a set of reference fields. The differenced SED of M78 shows excess emission at 10–70 GHz over free–free and a modified blackbody, at 3.4σ. The excess is matched by the spinning dust model from Draine & Lazarian.

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Paladini, Roberta0000-0002-5158-243X
Additional Information:© 2010 Universidad de Chile. Journal compilation © 2010 RAS. Accepted 2010 September 21. Received 2010 September 15; in original form 2010 January 18. Article first published online: 26 Nov. 2010. Thorough comments from an anonymous referee improved this manuscript. We thank Evelyne Roueff for interesting discussions on PDRs. SC acknowledges support from a Marie Curie International Incoming Fellowship (REA-236176), from FONDECYT grant 1100221, and from the Chilean Center for Astrophysics FONDAP 15010003. CD acknowledges an STFC Advanced Fellowship, and an ERC grant under the FP7. This work has been supported in part by the Strategic Alliance for the Implementation of New Technologies (SAINT – see This work has been carried out within the framework of a NASA/ADP ROSES-2009 grant, no. 09-ADP09-0059. The CBI observations were made possible, thanks to the engineering team: C. Achermann, R. Bustos, C. Jara, N. Oyarce, R. Reeves, M. Shepherd and C. Verdugo. We acknowledge the use of the Legacy Archive for Microwave Background Data Analysis (LAMBDA). Support for LAMBDA is provided by the NASA Office of Space Science. We used data from the Southern H-Alpha Sky Survey Atlas (SHASSA), which is supported by the National Science Foundation.
Funding AgencyGrant Number
Marie Curie International Fellowship REA-236176
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT) (Chile)1100221
Chilean Center for Astrophysics FONDAP15010003
Science and Technology Facilities Council (STFC) Advanced FellowshipUNSPECIFIED
Strategic Alliance for the Implementation of New Technologies (SAINT)UNSPECIFIED
NASA/ADP 09-ADP09-0059
NASA Office of Space ScienceUNSPECIFIED
Subject Keywords:radiation mechanisms: general; ISM: clouds; dust; extinction; infrared: ISM; radio continuum: ISM
Issue or Number:2
Record Number:CaltechAUTHORS:20110322-091232450
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Official Citation:Dust-correlated centimetre-wave radiation from the M78 reflection nebula (pages 1137–1150) Pablo Castellanos, Simon Casassus, Clive Dickinson, Matías Vidal, Roberta Paladini, Kieran Cleary, Rodney D. Davies, Richard J. Davis, Glenn J. White and Angela Taylor Article first published online: 26 NOV 2010 | DOI: 10.1111/j.1365-2966.2010.17743.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:23027
Deposited By: Ruth Sustaita
Deposited On:22 Mar 2011 21:06
Last Modified:03 Oct 2019 02:42

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