Issue |
A&A
Volume 582, October 2015
|
|
---|---|---|
Article Number | A31 | |
Number of page(s) | 32 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/201424955 | |
Published online | 30 September 2015 |
Planck intermediate results
XXVIII. Interstellar gas and dust in the Chamaeleon clouds as seen by Fermi LAT and Planck⋆
1
APC, AstroParticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3,
CEA/lrfu, Observatoire de Paris, Sorbonne Paris Cité,
10 rue Alice Domon et Léonie
Duquet,
75205
Paris Cedex 13,
France
2
African Institute for Mathematical Sciences,
6−8
Melrose Road, Muizenberg, 7950
Cape Town, South
Africa
3
Agenzia Spaziale Italiana Science Data Center, via del Politecnico
snc, 00133
Roma,
Italy
4
Agenzia Spaziale Italiana, Viale Liegi 26,
00186
Roma,
Italy
5
Astrophysics Group, Cavendish Laboratory, University of
Cambridge, J J Thomson
Avenue, Cambridge
CB3 0HE,
UK
6
Astrophysics & Cosmology Research Unit, School of
Mathematics, Statistics & Computer Science, University of
KwaZulu-Natal, Westville Campus,
Private Bag X54001, Durban
4000, South
Africa
7
Atacama Large Millimeter/submillimeter Array, ALMA Santiago
Central Offices, Alonso de Cordova
3107, Vitacura, Casilla 763 0355 Santiago, Chile
8
CITA, University of Toronto, 60 St. George St., Toronto, ON
M5S 3H8,
Canada
9
CNRS, IRAP, 9
Av. colonel Roche, BP
44346, 31028
Toulouse Cedex 4,
France
10
California Institute of Technology, Pasadena, A 91125
California, USA
11
Centro de Estudios de Física del Cosmos de Aragón (CEFCA), Plaza
San Juan, 1, planta 2, 44001
Teruel,
Spain
12
Computational Cosmology Center, Lawrence Berkeley National
Laboratory, Berkeley, CA94720
California, USA
13
Consejo Superior de Investigaciones Científicas
(CSIC), 117
Madrid,
Spain
14
DSM/Irfu/SPP, CEA-Saclay, 91191
Gif-sur-Yvette Cedex,
France
15
DTU Space, National Space Institute, Technical University of
Denmark, Elektrovej
327, 2800
Kgs. Lyngby,
Denmark
16
Département de Physique Théorique, Université de
Genève, 24 Quai E.
Ansermet, 1211
Genève 4,
Switzerland
17
Departamento de Física, Universidad de Oviedo,
Avda. Calvo Sotelo s/n,
33003
Oviedo,
Spain
18
Department of Astrophysics/IMAPP, Radboud University
Nijmegen, PO Box
9010, 6500 GL
Nijmegen, The
Netherlands
19
Department of Physics & Astronomy, University of British
Columbia, 6224 Agricultural Road,
Vancouver, BC
V6T 1Z1
British Columbia,
Canada
20
Department of Physics and Astronomy, Dana and David Dornsife
College of Letter, Arts and Sciences, University of Southern California,
Los Angeles, CA
90089,
USA
21
Department of Physics and Astronomy, University College
London, London
WC1E 6BT,
UK
22
Department of Physics, Florida State University, Keen Physics
Building, 77 Chieftan
Way, Tallahassee,
FL32306 Florida, USA
23
Department of Physics, Gustaf Hällströmin katu 2a, University of
Helsinki, 00014
Helsinki,
Finland
24
Department of Physics, Nagoya University,
Chikusa-ku, 464-8602,
Nagoya,
Japan
25
Department of Physics, Princeton University,
Princeton, New Jersey, NJ 08544
USA
26
Department of Physics, University of California,
Santa Barbara, California
CA93106, USA
27
Department of Physics, University of Illinois at
Urbana-Champaign, 1110 West Green
Street, Urbana,
Illinois, Il 61801 USA
28
Dipartimento di Fisica e Astronomia G. Galilei, Università degli
Studi di Padova, via Marzolo
8, 35131
Padova,
Italy
29
Dipartimento di Fisica e Scienze della Terra, Università di
Ferrara, via Saragat
1, 44122
Ferrara,
Italy
30
Dipartimento di Fisica, Università La Sapienza,
P.le A. Moro 2, 00185
Roma,
Italy
31
Dipartimento di Fisica, Università degli Studi di
Milano, via Celoria,
16, 20122
Milano,
Italy
32
Dipartimento di Fisica, Università degli Studi di
Trieste, via A. Valerio
2, 34128
Trieste,
Italy
33
Dipartimento di Fisica, Università di Roma Tor
Vergata, via della Ricerca
Scientifica, 1
00133
Roma,
Italy
34
Discovery Center, Niels Bohr Institute,
17 Blegdamsvej, 2100
Copenhagen,
Denmark
35
Dpto. Astrofísica, Universidad de La Laguna (ULL),
38206, La Laguna, Tenerife, Spain
36
European Southern Observatory, ESO Vitacura, Alonso de Cordova 3107, Vitacura, Casilla
19001, Santiago,
Chile
37
European Space Agency, ESAC, Planck Science Office, Camino bajo
del Castillo, s/n,Urbanización Villafranca del Castillo, 28692 Villanueva de la
Cañada, Madrid,
Spain
38
European Space Agency, ESTEC, Keplerlaan 1,
2201 AZ
Noordwijk, The
Netherlands
39
Facoltà di Ingegneria, Università degli Studi
e-Campus, via Isimbardi
10, 22060
Novedrate ( CO), Italy
40
HGSFP and University of Heidelberg, Theoretical Physics
Department, Philosophenweg
16, 69120
Heidelberg,
Germany
41
Helsinki Institute of Physics, Gustaf Hällströmin katu 2,
University of Helsinki, 00100
Helsinki,
Finland
42
INAF−Osservatorio
Astrofisico di Catania, via S. Sofia 78, 95123
Catania,
Italy
43
INAF−Osservatorio
Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122
Padova,
Italy
44
INAF−Osservatorio
Astronomico di Roma, via di Frascati 33, 00040
Monte Porzio Catone,
Italy
45
INAF−Osservatorio
Astronomico di Trieste, via G.B. Tiepolo 11, 34131
Trieste,
Italy
46
INAF/IASF Bologna, via Gobetti 101, 40127
Bologna,
Italy
47
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Milano,
Italy
48
INFN, Sezione di Bologna, via Irnerio 46,
40126
Bologna,
Italy
49
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Sapienza, Piazzale Aldo Moro
2, 00185
Roma,
Italy
50
INFN/National Institute for Nuclear Physics,
via Valerio 2, 34127
Trieste,
Italy
51
IPAG: Institut de Planétologie et d’Astrophysique de Grenoble,
Université Grenoble Alpes, IPAG, 38000 Grenoble, CNRS, France, IPAG, 38000
Grenoble,
France
52
Imperial College London, Astrophysics group, Blackett
Laboratory, Prince Consort
Road, London,
SW7 2AZ,
UK
53
Infrared Processing and Analysis Center, California Institute of
Technology, Pasadena,
CA
91125,
USA
54
Institut Universitaire de France, 103 Bd Saint-Michel, 75005
Paris,
France
55
Institut d’Astrophysique Spatiale, CNRS (UMR8617) Université
Paris-Sud 11, Bâtiment
121, 91405
Orsay,
France
56
Institut d’Astrophysique de Paris, CNRS (UMR7095),
98bis Boulevard Arago,
75014
Paris,
France
57
Institute for Space Sciences, 077125
Bucharest-Magurale,
Romania
58
Institute of Astronomy, University of Cambridge,
Madingley Road, Cambridge
CB3 0HA,
UK
59 Institute of Theoretical Astrophysics, University of Oslo,
1029 Blindern, Oslo, Norway
60
Instituto de Astrofísica de Canarias, C/vía Láctea s/n, La Laguna, 38205
Tenerife,
Spain
61
Instituto de Física de Cantabria (CSIC-Universidad de
Cantabria), Avda. de los Castros
s/n, 39005
Santander,
Spain
62
Jet Propulsion Laboratory, California Institute of
Technology, 4800 Oak Grove Drive,
Pasadena, CA91109
California, USA
63
Jodrell Bank Centre for Astrophysics, Alan Turing Building, School
of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13
9PL, UK
64
Kavli Institute for Cosmology Cambridge,
Madingley Road, Cambridge, CB3 0HA, UK
65
LAL, Université Paris-Sud, CNRS/IN2P3,
91400
Orsay,
France
66
LERMA, CNRS, Observatoire de Paris, 61 Avenue de
l’Observatoire, 75014
Paris,
France
67
Laboratoire AIM, IRFU/Service d’Astrophysique−CEA/DSM−CNRS −
Université Paris Diderot, Bât. 709, CEA-Saclay, 91191
Gif-sur-Yvette Cedex,
France
68
Laboratoire Traitement et Communication de l’Information, CNRS
(UMR 5141) and Télécom ParisTech, 46 rue Barrault
75634
Paris Cedex 13,
France
69
Laboratoire de Physique Subatomique et de Cosmologie, Université
Joseph Fourier Grenoble I, CNRS/IN2P3, Institut National Polytechnique de
Grenoble, 53 rue des
Martyrs, 38026
Grenoble Cedex,
France
70
Laboratoire de Physique Théorique, Université Paris-Sud 11
& CNRS, Bâtiment
210, 91405
Orsay,
France
71
Lawrence Berkeley National Laboratory,
Berkeley, California, USA
72
Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741
Garching,
Germany
73
Max-Planck-Institut für Extraterrestrische Physik,
Giessenbachstraße, 85748
Garching,
Germany
74
McGill Physics, Ernest Rutherford Physics Building, McGill
University, 3600 rue University, Montréal, QC,
H3A 2T8,
Canada
75
National University of Ireland, Department of Experimental
Physics, Maynooth,
Co. Kildare,
Ireland
76
Niels Bohr Institute, Blegdamsvej 17, 2100
Copenhagen,
Denmark
77
Observational Cosmology, Mail Stop 367-17, California Institute of
Technology, Pasadena,
CA, 91125, USA
78
SISSA, Astrophysics Sector, via Bonomea 265,
34136
Trieste,
Italy
79
School of Physics and Astronomy, Cardiff University,
Queens Buildings, The Parade,
Cardiff, CF24 3AA, UK
80
Space Research Institute (IKI), Russian Academy of
Sciences, Profsoyuznaya Str,
84/32, 117997
Moscow,
Russia
81
Space Sciences Laboratory, University of California,
Berkeley, California
94720,
USA
82
Special Astrophysical Observatory, Russian Academy of
Sciences, Nizhnij Arkhyz,
Zelenchukskiy region, 369167
Karachai-Cherkessian Republic,
Russia
83
Sub-Department of Astrophysics, University of
Oxford, Keble Road,
Oxford
OX1 3RH,
UK
84
UPMC Univ. Paris 06,UMR7095, 98bis boulevard Arago, 75014
Paris,
France
85
Université de Toulouse, UPS-OMP, IRAP, 31028
Toulouse Cedex 4,
France
86
Universities Space Research Association, Stratospheric Observatory
for Infrared Astronomy, MS
232-11, Moffett
Field, CA
94035,
USA
87
University of Granada, Departamento de Física Teórica y del
Cosmos, Facultad de Ciencias, 18071
Granada,
Spain
88
University of Granada, Instituto Carlos I de Física Teórica y
Computacional, 18071
Granada,
Spain
89
W. W. Hansen Experimental Physics Laboratory, Kavli Institute for
Particle Astrophysics and Cosmology, Department of Physics and SLAC National
Accelerator Laboratory, Stanford University, Stanford, CA
94305,
USA
90
Warsaw University Observatory, Aleje Ujazdowskie 4, 00-478
Warszawa,
Poland
Received: 10 September 2014
Accepted: 25 February 2015
The nearby Chamaeleon clouds have been observed in γ rays by the Fermi Large Area Telescope (LAT) and in thermal dust emission by Planck and IRAS. Cosmic rays and large dust grains, if smoothly mixed with gas, can jointly serve with the H i and 12CO radio data to (i) map the hydrogen column densities, NH, in the different gas phases, in particular at the dark neutral medium (DNM) transition between the H i-bright and CO-bright media; (ii) constrain the CO-to-H2 conversion factor, XCO; and (iii) probe the dust properties per gas nucleon in each phase and map their spatial variations across the clouds. We have separated clouds at local, intermediate, and Galactic velocities in H i and 12CO line emission to model in parallel the γ-ray intensity recorded between 0.4 and 100 GeV; the dust optical depth at 353 GHz, τ353; the thermal radiance of the large grains; and an estimate of the dust extinction, AVQ, empirically corrected for the starlight intensity. The dust and γ-ray models have been coupled to account for the DNM gas. The consistent γ-ray emissivity spectra recorded in the different phases confirm that the GeV–TeV cosmic rays probed by the LAT uniformly permeate all gas phases up to the 12CO cores. The dust and cosmic rays both reveal large amounts of DNM gas, with comparable spatial distributions and twice as much mass as in the CO-bright clouds. We give constraints on the H i-DNM-CO transitions for five separate clouds. CO-dark H2 dominates the molecular columns up to AV ≃ 0.9 and its mass often exceeds the one-third of the molecular mass expected by theory. The corrected AVQ extinction largely provides the best fit to the total gas traced by the γ rays. Nevertheless, we find evidence for a marked rise in AVQ/NH with increasing NH and molecular fraction, and with decreasing dust temperature. The rise in τ353/NH is even steeper. We observe variations of lesser amplitude and orderliness for the specific power of the grains, except for a coherent decline by half in the CO cores. This combined information suggests grain evolution. We provide average values for the dust properties per gas nucleon in the different phases. The γ rays and dust radiance yield consistent XCO estimates near 0.7 × 1020 cm-2 K-1 km-1 s. The AVQ and τ353 tracers yield biased values because of the large rise in grain opacity in the CO clouds. These results clarify a recurrent disparity in the γ-ray versus dust calibration of XCO, but they confirm the factor of 2 difference found between the XCO estimates in nearby clouds and in the neighbouring spiral arms.
Key words: ISM: structure / gamma rays: ISM / cosmic rays / dust, extinction / local insterstellar matter
Appendices are available in electronic form at http://www.aanda.org
© ESO, 2015
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