Mapping the properties of blue compact dwarf galaxies: integral field spectroscopy with PMAS

Abstract

Context. Blue compact dwarf (BCD) galaxies are low-luminosity, low-metal content dwarf systems undergoing violent bursts of star formation. They present a unique opportunity to probe galaxy formation and evolution and to investigate the process of star formation in a relatively simple scenario. Spectrophotometric studies of BCDs are essential to disentangle and characterize their stellar populations. Aims. We perform integral field spectroscopy of a sample of BCDs with the aim of analyzing their morphology, the spatial distribution of some of their physical properties (excitation, extinction, and electron density) and their relationship with the distribution and evolutionary state of the stellar populations. Methods. Integral field spectroscopy observations of the sample galaxies were carried out with the Potsdam Multi-Aperture Spectrophotometer (PMAS) at the 3.5 m telescope at Calar Alto Observatory. An area 16 × 16 in size was mapped with a spatial sampling of 1 × 1 . We obtained data in the 3590−6996 Å spectral range, with a linear dispersion of 3.2 Å per pixel. From these data we built two-dimensional maps of the flux of the most prominent emission lines, of two continuum bands, of the most relevant line ratios, and of the gas velocity field. Integrated spectra of the most prominent star-forming regions and of whole objects within the FOV were used to derive their physical parameters and the gas metal abundances. Results. Six galaxies display the same morphology both in emission line and in continuum maps; only in two objects, Mrk 32 and Tololo 1434+032, the distributions of the ionized gas and of the stars differ considerably. In general the different excitation maps for a same object display the same pattern and trace the star-forming regions, as expected for objects ionized by hot stars; only the outer

Coevolution of metallicity and star formation in galaxies toz≃ 3.7 – I. A Fundamental Plane

“…Total Hα fluxes were taken from Dopita et al (2002) Kennicutt et al (2008);Cairós et al (2010); James et al (2010) and 24 µm measurements from Engelbracht et al (2008). When these data were unavailable (9 galaxies), we adopted the SFR(TIR) prescription by Murphy et al (2011) using the fluxes by Engelbracht et al (2008).…”

Integral field observations of the blue compact galaxy Haro14

“…Integral field unit (IFU) instruments are particularly suited to probe small, highly asymmetric and compact systems such as BCGs because in just one shot they provide spectrophotometric and kinematic information on a large portion of the galaxy; generally the whole starburst is covered. A detailed description of the project as well as our first results can be found in Cairós et al (2009bCairós et al ( ,a, 2010Cairós et al ( , 2012Cairós et al ( , 2015.…”

Ionization processes in a local analogue of distant clumpy galaxies: VLT MUSE IFU spectroscopy and FORS deep images of the TDG NGC 5291N

“…Former IFU observations of dwarf galaxies have already given us some insight into the ionization properties of these galaxies (Izotov et al 2006;Lagos et al 2009Lagos et al , 2012Lagos et al , 2014James et al 2009James et al , 2010James et al , 2013a and have led to identifying (i) regions with Wolf-Rayet stars (Cairós et al 2010;Kehrig et al 2013); (ii) the presence of non-thermal ionization processes such as shocks (Cairós et al 2010); or (iii) the existence of a central AGN (Cairós et al 2009). To our knowledge, this paper is only the second one presenting MUSE observations of a dwarf galaxy and the first one focused on a colliding system.…”