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Title: The system LS 5039: a new massive radio emitting
X-ray binary
Authors: Marti, J.; Paredes, J. M.; Ribo, M.
Affiliation: AA( Departamento de Fisica Aplicada, Escuela
Politecnica Superior, Universidad de Jaen, Calle
Virgen de la Cabeza, 2, E-23071 Jaen, Spain;
DAPNIA/Service d'Astrophysique, CEA/Saclay, F-91191
Gif-Sur-Yvette, France), AB(Departament d'Astronomia
i Meteorologia, Universitat de Barcelona, Av.
Diagonal 647, E-08028 Barcelona, Spain),
AC(Departament d'Astronomia i Meteorologia,
Universitat de Barcelona, Av. Diagonal 647, E-08028
Barcelona, Spain)
Journal: Astronomy and Astrophysics, v.338, p.L71-L74 (1998)
(A&A Homepage)
Publication Date: 10/1998
Origin: A&A
A&A Keywords: STARS: INDIVIDUAL: LS 5039, STARS: VARIABLES: OTHER,
RADIO CONTINUUM: STARS, X-RAYS: STARS
Abstract Copyright: (c) 1998: Astronomy & Astrophysics
Bibliographic Code: 1998A&A...338L..71M
Abstract
We report the discovery of a bright and unresolved radio counterpart to
the massive X-ray binary LS 5039. The optical position of this early
type star is in excellent agreement with that measured in the radio. The
observed spectrum is clearly of non-thermal synchrotron nature and some
evidences of variability, although with moderate amplitude, have been
detected at both radio and optical wavelengths. All the available data
strongly support that LS 5039 is a new member in the reduced family of
radio loud massive X-ray binaries.
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Title: X-ray and radio observations of RX J1826.2-1450/LS
5039
Authors: Ribó, M.; Reig, P.; Martí, J.; Paredes, J. M.
Affiliation: AA( Departament d'Astronomia i Meteorologia,
Universitat de Barcelona, Av. Diagonal 647, E-08028
Barcelona, Spain), AB(Physics Department, University
of Crete, P.O. Box 2208, GR-71003, Heraklion,
Greece; Foundation for Research and
Technology-Hellas, GR-71110, Heraklion, Crete,
Greece), AC(Departamento de Física, Escuela
Politécnica Superior, Universidad de Jaén, Calle
Virgen de la Cabeza, 2, E-23071 Jaén, Spain), AD(
Departament d'Astronomia i Meteorologia, Universitat
de Barcelona, Av. Diagonal 647, E-08028 Barcelona,
Spain)
Journal: Astronomy and Astrophysics, v.347, p.518-523 (1999)
(A&A Homepage)
Publication Date: 07/1999
Origin: A&A
A&A Keywords: STARS: INDIVIDUAL: RX J1826.2-1450, LS 5039, NVSS
J182614-145054, STARS: VARIABLES: GENERAL, RADIO
CONTINUUM: STARS, X-RAYS: STARS
Abstract Copyright: (c) 1999: Astronomy & Astrophysics
Bibliographic Code: 1999A&A...347..518R
Abstract
RX J1826.2-1450/LS 5039 has been recently proposed to be a radio
emitting high mass X-ray binary. In this paper, we present an analysis
of its X-ray timing and spectroscopic properties using different
instruments on board the RXTE satellite. The timing analysis indicates
the absence of pulsed or periodic emission on time scales of 0.02-2000 s
and 2-200 d, respectively. The source spectrum is well represented by a
power-law model, plus a Gaussian component describing a strong iron line
at 6.6 keV. Significant emission is seen up to 30 keV, and no
exponential cut-off at high energy is required. We also study the radio
properties of the system according to the GBI-NASA Monitoring Program.
RX J1826.2-1450/LS 5039 continues to display moderate radio variability
with a clearly non-thermal spectral index. No strong radio outbursts
have been detected after several months.
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Title: VLA/GBI observations of the new high mass X-ray
binary LS 5039
Authors: Ribó, M.; Paredes, J. M.; Martí, J.
Affiliation: AA(Departament d'Astronomia i Meteorologia,
Universitat de Barcelona, Av. Diagonal 647, E-08028
Barcelona, Spain), AB(Departament d'Astronomia i
Meteorologia, Universitat de Barcelona, Av. Diagonal
647, E-08028 Barcelona, Spain), AC(Departamento de
Física Aplicada, Escuela Politécnica Superior,
Universidad de Jaén, Calle Virgen de la Cabeza, 2,
E-23071 Jaén, Spain)
Journal: New Astronomy Reviews, Volume 43, Issue 8-10, p.
545-547.
Publication Date: 11/1999
Origin: ELSEVIER
Abstract Copyright: (c) 1999 Elsevier Science B.V. All rights reserved.
Bibliographic Code: 1999NewAR..43..545R
Abstract
Electronic Article Available from Elsevier Science.
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Title: LS 5039, a Microquasar with Persistent Radio and
γ-ray Emission
Authors: Ribó, M.; Paredes, J. M.; Martí, J.; Massi, M.
Affiliation: AA(Departament d'Astronomia i Meteorologia,
Universitat de Barcelona, Av. Diagonal 647, E-08028
Barcelona, Spain), AB(Departament d'Astronomia i
Meteorologia, Universitat de Barcelona, Av. Diagonal
647, E-08028 Barcelona, Spain), AC(Departamento de
Física, Escuela Politécnica Superior, Universidad de
Jaén, Calle Virgen de la Cabeza 2, E-23071 Jaén,
Spain), AD(Max Planck Institut für Radioastronomie,
Auf dem Hügel 69, D-53121 Bonn, Germany)
Journal: Abstracts from a conference held in Granada, 17-20
of September 2000 and hosted by the Instituto de
Radioastronomia Millimetrica (URAM), Universidad de
Granada and Instituto de Astrofisica de Andalucia
(IAA).
Publication Date: 00/2000
Origin: AUTHOR
Bibliographic Code: 2000yera.confE..44R
Abstract
Microquasars are x-ray binary systems that share both morphological and
physical analogies with the extragalactic quasars. Only about 10 of such
systems are known in our Galaxy, and their most relevant fingerprint at
radio wavelengths is the presence of bipolar radio jets with
relativistic flow velocities. A promising candidate to be a new member
of this group was initially selected after cross-correlating radio,
x-ray and optical databases. We refer here to the x-ray binary LS 5039,
with galactic coordinates l = 16.88circ and b =
-1.29circ. This is a massive system located 3 kpc away, with
an early type optical companion, hard x-ray spectrum and persistent
non-thermal radio emission (Sν propto
ν-0.5). This last property was evidenced after eleven
months of daily monitoring conducted by the Green Bank Interferometer
(GBI) at our request.
The microquasar nature of LS 5039 was finally revealed thanks to VLBA
and phased VLA observations at 6 cm wavelength carried out on 8 May
1999. The plot of visibility amplitudes versus baseline length provided
the first indication that the source was resolved at milliarcsecond
angular scales. In the resulting synthesis map the source appears
clearly elongated with a jet-like geometry emanating from a central core
and extending over six milliarcseconds. The jet components account for
20% of the total 16 mJy flux density and their brightness asymmetry
suggests a possible Doppler boosting effect. If this interpretation is
correct, a flow velocity higher than (0.15 ± 0.04)c is inferred.
This hypotesis will be tested with future VLBA observations.
On the other hand, the detection of radio jets took place at a time
when the system was only moderately variable in the radio, and no
precursor flaring event occurred in the weeks before the observation
according to the GBI. This points to the radio jets as being a permanent
feature in LS 5039 that powers its typical radio luminosity of 7.5 times
1030 erg s-1 . We note that most microquasar
discoveries were possible after detecting a strong x-ray outburst event.
This has not been the case of LS 5039, and possibly other similar
microquasars may be found by using the same cross-correlation technique
mentioned above.
Moreover, the Energetic Gamma Ray Experiment Telescope (EGRET) on board
the COMPTON-Gamma Ray Observatory satellite detected 271 high energy
sources of E>100 MeV photons, and nearly 170 of them remain to be
identified. After the release of the third EGRET catalog, we noticed
that the position of LS 5039 is well inside the 95% confidence contour
of 3EG J1824-1514, an apparently persistent source of high energy
γ-rays in the Galactic Plane. This fact strongly suggests a likely
relationship between this microquasar and one of the unidentified EGRET
sources. Although the EGRET position error is about 0.5circ,
LS 5039 is the only bright ROSAT x-ray emitter within
1circ
of 3EG J1824-1514. Concerning the physical emission mechanism, we
propose that the E > 100 MeV photons arise as a result of inverse
Compton scattering of ultraviolet stellar photons by the same
synchrotron radio emitting electrons.
The possible association of an EGRET source with a radio loud x-ray
binary opens the possibility that part of the unidentified EGRET sources
may be associated with galactic relativistic jets. Taking into account
the modest nature of LS 5039 at x-ray and optical wavelengths, it would
not be surprising if several similar objets are identified in the
future.