Bibcode
Amorín, R.; Pérez-Montero, E.; Contini, T.; Vílchez, J. M.; Bolzonella, M.; Tasca, L. A. M.; Lamareille, F.; Zamorani, G.; Maier, C.; Carollo, C. M.; Kneib, J.-P.; Le Fèvre, O.; Lilly, S.; Mainieri, V.; Renzini, A.; Scodeggio, M.; Bardelli, S.; Bongiorno, A.; Caputi, K.; Cucciati, O.; de la Torre, S.; de Ravel, L.; Franzetti, P.; Garilli, B.; Iovino, A.; Kampczyk, P.; Knobel, C.; Kovač, K.; Le Borgne, J.-F.; Le Brun, V.; Mignoli, M.; Pellò, R.; Peng, Y.; Presotto, V.; Ricciardelli, E.; Silverman, J. D.; Tanaka, M.; Tresse, L.; Vergani, D.; Zucca, E.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 578, id.A105, 20 pp.
Fecha de publicación:
6
2015
Revista
Número de citas
97
Número de citas referidas
85
Descripción
Context. The study of large and representative samples of
low-metallicity star-forming galaxies at different cosmic epochs is of
great interest to the detailed understanding of the assembly history and
evolution of low-mass galaxies. Aims: We present a thorough
characterization of a large sample of 183 extreme emission-line galaxies
(EELGs) at redshift 0.11 ≤ z ≤ 0.93 selected from the 20k zCOSMOS
bright survey because of their unusually large emission line equivalent
widths. Methods: We use multiwavelength COSMOS photometry,
HST-ACS I-band imaging, and optical zCOSMOS spectroscopy to derive the
main global properties of star-forming EELGs, such as sizes, stellar
masses, star formation rates (SFR), and reliable oxygen abundances using
both "direct" and "strong-line" methods. Results: The EELGs are
extremely compact (r50 ~ 1.3 kpc), low-mass
(M∗ ~ 107-1010
M⊙) galaxies forming stars at unusually high specific
star formation rates (sSFR ≡ SFR/M⋆ up to
10-7 yr-1) compared to main sequence star-forming
galaxies of the same stellar mass and redshift. At rest-frame UV
wavelengths, the EELGs are luminous and show high surface brightness and
include strong Lyα emitters, as revealed by GALEX spectroscopy. We
show that zCOSMOS EELGs are high-ionization, low-metallicity systems,
with median 12+log (O/H) = 8.16 ± 0.21 (0.2 Z⊙)
including a handful of extremely metal-deficient (<0.1
Z⊙) EELGs. While ~80% of the EELGs show non-axisymmetric
morphologies, including clumpy and cometary or tadpole galaxies, we find
that ~29% of them show additional low-surface-brightness features, which
strongly suggests recent or ongoing interactions. As star-forming dwarfs
in the local Universe, EELGs are most often found in relative isolation.
While only very few EELGs belong to compact groups, almost one third of
them are found in spectroscopically confirmed loose pairs or triplets.
Conclusions: The zCOSMOS EELGs are galaxies caught in a transient
and probably early period of their evolution, where they are efficiently
building up a significant fraction of their present-day stellar mass in
an ongoing, galaxy-wide starburst. Therefore, the EELGs constitute an
ideal benchmark for comparison studies between low- and high-redshift
low-mass star-forming galaxies.
Full Tables 1 and 2 are only available at the CDS via anonymous ftp to
http://cdsarc.u-strasbg.fr
(ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/578/A105