Discovery of carbon radio recombination lines in absorption towards Cygnus A
Artikel i vetenskaplig tidskrift, 2014
We present the first detection of carbon radio recombination line absorption along the line of sight to Cygnus A. The observations were carried out with the Low Frequency Array in the 33-57 MHz range. These low-frequency radio observations provide us with a new line of sight to study the diffuse, neutral gas in our Galaxy. To our knowledge this is the first time that foreground Milky Way recombination line absorption has been observed against a bright extragalactic background source. By stacking 48 carbon alpha lines in the observed frequency range we detect carbon absorption with a signal-to-noise ratio of about 5. The average carbon absorption has a peak optical depth of 2 x 10(-4), a line width of 10 km s(-1) and a velocity of +4 km s(-1) with respect to the local standard of rest. The associated gas is found to have an electron temperature T-e similar to 110 K and density n(e) similar to 0.06 cm(-3). These properties imply that the observed carbon alpha absorption likely arises in the cold neutral medium of the Orion arm of the Milky Way. Hydrogen and helium lines were not detected to a 3 Sigma peak optical depth limit of 1.5 x 10(-4) for a 4 km s(-1) channel width. Radio recombination lines associated with Cygnus A itself were also searched for, but are not detected. We set a 3 Sigma upper limit of 1.5 x 10(-4) for the peak optical depth of these lines for a 4 km s(-1) channel width.
structure-local interstellar matter-radio lines
General-IsM
ISM
IsM.
Författare
J. B. R. Oonk
Netherlands Institute for Radio Astronomy (ASTRON)
R. J. van Weeren
Universiteit Leiden
Netherlands Institute for Radio Astronomy (ASTRON)
Harvard-Smithsonian Center for Astrophysics
F. Salgado
Universiteit Leiden
L. K. Morabito
Universiteit Leiden
Aggm Tielens
Universiteit Leiden
H. Rottgering
Universiteit Leiden
A. Asgekar
Netherlands Institute for Radio Astronomy (ASTRON)
G. J. White
The Open University
STFC Rutherford Appleton Laboratory
A. Alexov
Universiteit Van Amsterdam
Space Telescope Science Institute (STScI)
J. Anderson
Max-Planck-Gesellschaft
I. M. Avruch
Netherlands Institute for Space Research (SRON)
Fabien Batejat
Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik
R. Beck
Max-Planck-Gesellschaft
M. E. Bell
The University of Sydney
I. van Bemmel
Netherlands Institute for Radio Astronomy (ASTRON)
M. J. Bentum
Netherlands Institute for Radio Astronomy (ASTRON)
G. Bernardi
Square Kilometre Array, South Africa
Rhodes University
P. Best
University of Edinburgh
A. Bonafede
Universität Hamburg
F. Breitling
Leibniz-Gemeinschaft
M. Brentjens
Netherlands Institute for Radio Astronomy (ASTRON)
J. Broderick
University of Southampton
M. Brüggen
Universität Hamburg
H. R. Butcher
Australian National University
B. Ciardi
Max-Planck-Gesellschaft
John Conway
Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium
A. Corstanje
Radboud Universiteit
F. De Gasperin
Universität Hamburg
E. de Geus
Netherlands Institute for Radio Astronomy (ASTRON)
M. de Vos
Netherlands Institute for Radio Astronomy (ASTRON)
S. Duscha
Netherlands Institute for Radio Astronomy (ASTRON)
J. Eisloffel
Thüringer Landessternwarte Tautenburg
D. Engels
Hamburger Sternwarte
J. van Enst
Netherlands Institute for Radio Astronomy (ASTRON)
H. Falcke
Netherlands Institute for Radio Astronomy (ASTRON)
Radboud Universiteit
R. A. Fallows
Netherlands Institute for Radio Astronomy (ASTRON)
R. Fender
University of Southampton
C. Ferrari
Université Nice Sophia Antipolis (UNS)
W. Frieswijk
Netherlands Institute for Radio Astronomy (ASTRON)
M. A. Garrett
Netherlands Institute for Radio Astronomy (ASTRON)
Universiteit Leiden
J. Griessmeier
Universite d'Orleans
J. P. Hamaker
Netherlands Institute for Radio Astronomy (ASTRON)
T. E. Hassall
University of Manchester
University of Southampton
The University of Sydney
G. Heald
Netherlands Institute for Radio Astronomy (ASTRON)
J. W. T. Hessels
Netherlands Institute for Radio Astronomy (ASTRON)
Universiteit Van Amsterdam
M. Hoeft
Thüringer Landessternwarte Tautenburg
A. Horneffer
Max-Planck-Gesellschaft
A. van der Horst
Universiteit Van Amsterdam
M. Iacobelli
Universiteit Leiden
N. J. Jackson
University of Manchester
E. Juette
Ruhr-Universität Bochum
A. Karastergiou
University of Oxford
W. Klijn
Netherlands Institute for Radio Astronomy (ASTRON)
J. Kohler
Max-Planck-Gesellschaft
V. I. Kondratiev
Netherlands Institute for Radio Astronomy (ASTRON)
Astro Space Center of Lebedev Physical Institute
M. Kramer
University of Manchester
Max-Planck-Gesellschaft
M. Kuniyoshi
Max-Planck-Gesellschaft
G. Kuper
Netherlands Institute for Radio Astronomy (ASTRON)
J. van Leeuwen
Netherlands Institute for Radio Astronomy (ASTRON)
University of Southampton
P. Maat
Netherlands Institute for Radio Astronomy (ASTRON)
G. Macario
Université Nice Sophia Antipolis (UNS)
G. Mann
Leibniz-Gemeinschaft
S. Markoff
Universiteit Van Amsterdam
J. P. McKean
Netherlands Institute for Radio Astronomy (ASTRON)
M. Mevius
Netherlands Institute for Radio Astronomy (ASTRON)
Kapteyn Astronomical Institute
J. C. A. Miller-Jones
Universiteit Van Amsterdam
Curtin University
J. D. Mol
Netherlands Institute for Radio Astronomy (ASTRON)
D. D. Mulcahy
Max-Planck-Gesellschaft
H. Munk
Netherlands Institute for Radio Astronomy (ASTRON)
M. J. Norden
Netherlands Institute for Radio Astronomy (ASTRON)
E. Orru
Netherlands Institute for Radio Astronomy (ASTRON)
H. Paas
Rijksuniversiteit Groningen
M. Pandey-Pommier
Observatoire de Lyon
V. N. Pandey
Netherlands Institute for Radio Astronomy (ASTRON)
R. Pizzo
Netherlands Institute for Radio Astronomy (ASTRON)
A. G. Polatidis
Netherlands Institute for Radio Astronomy (ASTRON)
W. Reich
Max-Planck-Gesellschaft
A. M. M. Scaife
University of Southampton
A. Schoenmakers
Netherlands Institute for Radio Astronomy (ASTRON)
D. Schwarz
Universität Bielefeld
A. Shulevski
Kapteyn Astronomical Institute
J. Sluman
Netherlands Institute for Radio Astronomy (ASTRON)
O. Smirnov
Rhodes University
Square Kilometre Array, South Africa
C. Sobey
Max-Planck-Gesellschaft
B. W. Stappers
University of Manchester
M. Steinmetz
Leibniz-Gemeinschaft
J. Swinbank
Universiteit Van Amsterdam
M. Tagger
Universite d'Orleans
Y. Tang
Netherlands Institute for Radio Astronomy (ASTRON)
C. Tasse
Observatoire de Paris-Meudon
S. ter Veen
Radboud Universiteit
S. Thoudam
Radboud Universiteit
C. Toribio
Netherlands Institute for Radio Astronomy (ASTRON)
R. van Nieuwpoort
Netherlands Institute for Radio Astronomy (ASTRON)
Netherlands eScience Center
R. Vermeulen
Netherlands Institute for Radio Astronomy (ASTRON)
C. Vocks
Leibniz-Gemeinschaft
C. Vogt
Netherlands Institute for Radio Astronomy (ASTRON)
Ramj Wijers
Universiteit Van Amsterdam
M. W. Wise
Netherlands Institute for Radio Astronomy (ASTRON)
O. Wucknitz
Max-Planck-Gesellschaft
Universität Bonn
S. Yatawatta
Netherlands Institute for Radio Astronomy (ASTRON)
P. Zarka
The Open University
A. Zensus
Max-Planck-Gesellschaft
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 437 4 3506-3515Ämneskategorier (SSIF 2011)
Astronomi, astrofysik och kosmologi
Infrastruktur
Onsala rymdobservatorium
DOI
10.1093/mnras/stt2158