Bibcode
Martí, J.; Paredes, J. M.; Bloom, J. S.; Casares, J.; Ribó, M.; Falco, E. E.
Referencia bibliográfica
Astronomy and Astrophysics, v.413, p.309-315 (2004)
Fecha de publicación:
1
2004
Revista
Número de citas
16
Número de citas referidas
13
Descripción
We report optical spectroscopic observations of a sample of 6
low-galactic latitude microquasar candidates selected by
cross-identification of X-ray and radio point source catalogs for
|bII | ≤ 5 °. Two objects resulted to be of clear
extragalactic origin, as an obvious cosmologic redshift has been
measured from their emission lines. For the rest, none exhibits a clear
stellar-like spectrum as would be expected for genuine Galactic
microquasars. Their featureless spectra are consistent with being
extragalactic in origin although two of them could be also highly
reddened stars. The apparent non-confirmation of our candidates suggests
that the population of persistent microquasar systems in the Galaxy is
more rare than previously believed. If none of them is galactic, the
upper limit to the space density of new Cygnus
X-3-like microquasars within 15 kpc would be ła1.1
× 10-12 pc-3. A similar upper limit for new
LS 5039-like systems within 4 kpc is estimated to be
ła5.6 × 10-11 pc-3.