Bibcode
Miralles-Caballero, D.; Díaz, A. I.; López-Sánchez, Á. R.; Rosales-Ortega, F. F.; Monreal-Ibero, A.; Pérez-Montero, E.; Kehrig, C.; García-Benito, R.; Sánchez, S. F.; Walcher, C. J.; Galbany, L.; Iglesias-Páramo, J.; Vílchez, J. M.; González Delgado, R. M.; van de Ven, G.; Barrera-Ballesteros, J.; Lyubenova, M.; Meidt, S.; Falcon-Barroso, J.; Mast, D.; Mendoza, M. A.; Califa Collaboration
Bibliographical reference
Astronomy and Astrophysics, Volume 592, id.A105, 31 pp.
Advertised on:
8
2016
Journal
Citations
17
Refereed citations
16
Description
The search of extragalactic regions with conspicuous presence of
Wolf-Rayet (WR) stars outside the Local Group is challenging task owing
to the difficulty in detecting their faint spectral features. In this
exploratory work, we develop a methodology to perform an automated
search of WR signatures through a pixel-by-pixel analysis of integral
field spectroscopy (IFS) data belonging to the Calar Alto Legacy
Integral Field Area survey, CALIFA. This procedure has been applied to a
sample of nearby galaxies spanning a wide range of physical,
morphological, and environmental properties. This technique allowed us
to build the first catalogue of regions rich in WR stars with spatially
resolved information, and enabled us to study the properties of these
complexes in a two-dimensional (2D) context. The detection technique is
based on the identification of the blue WR bump (around He
iiλ4686 Å, mainly associated with nitrogen-rich WR stars;
WN) and the red WR bump (around C ivλ5808 Å, mainly
associated with carbon-rich WR stars; WC) using a pixel-by-pixel
analysis that maximizes the number of independent regions within a given
galaxy. We identified 44 WR-rich regions with blue bumps distributed in
25 out of a total of 558 galaxies. The red WR bump was identified only
in 5 of those regions. Most of the WR regions are located within one
effective radius from the galaxy centre, and around one-third are
located within ~1 kpc or less from the centre. We found that the
majority of the galaxies hosting WR populations in our sample are
involved in some kind of interaction process. Half of the host galaxies
share some properties with gamma-ray burst (GRB) hosts where WR stars,
such as potential candidates to the progenitors of GRBs, are found. We
also compared the WR properties derived from the CALIFA data with
stellar population synthesis models, and confirm that simple star models
are generally not able to reproduce the observations. We conclude that
other effects, such as binary star channel (which could extend theWR
phase up to 10 Myr), fast rotation, or other physical processes that
cause the loss of observed Lyman continuum photons, very likely affect
the derived WR properties, and hence should be considered when modelling
the evolution of massive stars.
Based on observations collected at the Centro Astronómico
Hispano-Alemán (CAHA) at Calar Alto, operated jointly by the
Max-Planck Institut für Astronomie and the Instituto de
Astrofísica de Andalucía (CSIC).