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.

ISM

IsM.

General-IsM

structure-local interstellar matter-radio lines

Författare

J. B. R. Oonk

Netherlands Institute for Radio Astronomy (ASTRON)

R. J. van Weeren

Netherlands Institute for Radio Astronomy (ASTRON)

Harvard-Smithsonian Center for Astrophysics

Universiteit Leiden

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

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

Rhodes University

Square Kilometre Array, South Africa

P. Best

University of Edinburgh

A. Bonafede

Universität Hamburg

F. Breitling

Leibniz-Institut Für Astrophysik Potsdam

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

Radboud Universiteit

Netherlands Institute for Radio Astronomy (ASTRON)

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 Southampton

The University of Sydney

University of Manchester

G. Heald

Netherlands Institute for Radio Astronomy (ASTRON)

J. W. T. Hessels

Universiteit Van Amsterdam

Netherlands Institute for Radio Astronomy (ASTRON)

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

Max-Planck-Gesellschaft

University of Manchester

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-Institut Für Astrophysik Potsdam

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

Square Kilometre Array, South Africa

Rhodes University

C. Sobey

Max-Planck-Gesellschaft

B. W. Stappers

University of Manchester

M. Steinmetz

Leibniz-Institut Für Astrophysik Potsdam

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-Institut Für Astrophysik Potsdam

C. Vogt

Netherlands Institute for Radio Astronomy (ASTRON)

Ramj Wijers

Universiteit Van Amsterdam

M. W. Wise

Netherlands Institute for Radio Astronomy (ASTRON)

O. Wucknitz

Universität Bonn

Max-Planck-Gesellschaft

S. Yatawatta

Netherlands Institute for Radio Astronomy (ASTRON)

P. Zarka

Open University

A. Zensus

Max-Planck-Gesellschaft

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 437 4 3506-3515

Ämneskategorier (SSIF 2011)

Astronomi, astrofysik och kosmologi

Infrastruktur

Onsala rymdobservatorium

DOI

10.1093/mnras/stt2158

Mer information

Senast uppdaterat

2025-03-17