We present a study of the HII regions in the galaxy NGC 6754 from a two pointing mosaic comprising 197,637 individual spectra, using Integral Field Spectrocopy (IFS) recently acquired with the MUSE instrument during its Science Verification program.
The data cover the entire galaxy out to ~2 effective radii (re ), sampling its morphological structures with unprecedented spatial resolution for a wide-field IFU. A complete census of the H ii regions limited by the atmospheric seeing conditions was derived, comprising 396 individual ionized sources. This is one of the largest and most complete catalogue of H ii regions with spectroscopic information in a single galaxy. We use this catalogue to derive the radial abundance gradient in this SBb galaxy, finding a negative gradient with a slope consistent with the characteristic value for disk galaxies recently reported. The large number of H ii regions allow us to estimate the typical mixing scale-length (rmix ~0.4 re ), which sets strong constraints on the proposed mechanisms for metal mixing in disk galaxies, like radial movements associated with bars and spiral arms, when comparing with simulations. We found evidence for an azimuthal variation of the oxygen abundance, that may be related with the radial migration. These results illustrate the unique capabilities of MUSE for the study of the enrichment mechanisms in Local Universe galaxies.
H ii regions in galaxies are the sites of star formation and thus particular places to understand the build-up of stellar mass in the universe. The line ratios of this ionized gas are frequently used to characterize the ionization conditions. We use
the Hii regions catalogue from the CALIFA survey (~5000 H ii regions), to explore their distribution across the classical [OIII]/Hbeta vs. [NII]/Halpha diagnostic diagram, and how it depends on the oxygen abundance, ionization parameter, electron density, and dust attenuation. We compared the line ratios with predictions from photoionization models. Finally, we explore the dependences on the properties of the host galaxies, the location within those galaxies and the properties of the underlying stellar population. We found that the location within the BPT diagrams is not totally predicted by photoionization models. Indeed, it depends on the properties of the host galaxies, their galactocentric distances and the properties of the underlying stellar population. These results indicate that although H ii regions are short lived events, they are affected by the total underlying stellar population. One may say that H ii regions keep a memory of the stellar evolution and chemical enrichment that have left an imprint on the both the ionizing stellar population and the ionized gas
We present the largest and most homogeneous catalog of HII regions and associations compiled so far. The catalog comprises more than 7000 ionized regions, extracted from 306 galaxies observed by the CALIFA survey. We describe the procedures used to d
etect, select, and analyse the spectroscopic properties of these ionized regions. In the current study we focus on the characterization of the radial gradient of the oxygen abundance in the ionized gas, based on the study of the deprojected distribution of HII regions. We found that all galaxies without clear evidence of an interaction present a common gradient in the oxygen abundance, with a characteristic slope of alpha = -0.1 dex/re between 0.3 and 2 disk effective radii, and a scatter compatible with random fluctuations around this value, when the gradient is normalized to the disk effective radius. The slope is independent of morphology, incidence of bars, absolute magnitude or mass. Only those galaxies with evidence of interactions and/or clear merging systems present a significant shallower gradient, consistent with previous results. The majority of the 94 galaxies with H ii regions detected beyond 2 disk effective radii present a flattening in the oxygen abundance. The flattening is statistically significant. We cannot provide with a conclusive answer regarding the origin of this flattening. However, our results indicate that its origin is most probably related to the secular evolution of galaxies. Finally, we find a drop/truncation of the oxygen abundance in the inner regions for 26 of the galaxies. All of them are non-interacting, mostly unbarred, Sb/Sbc galaxies. This feature is associated with a central star-forming ring, which suggests that both features are produced by radial gas flows induced by resonance processes.
We present the results on the study of the global and local M-Z relation based on the first data available from the CALIFA survey (150 galaxies). This survey provides integral field spectroscopy of the complete optical extent of each galaxy (up to 2-
3 effective radii), with enough resolution to separate individual HII regions and/or aggregations. Nearly $sim$3000 individual HII regions have been detected. The spectra cover the wavelength range between [OII]3727 and [SII]6731, with a sufficient signal-to-noise to derive the oxygen abundance and star-formation rate associated with each region. In addition, we have computed the integrated and spatially resolved stellar masses (and surface densities), based on SDSS photometric data. We explore the relations between the stellar mass, oxygen abundance and star-formation rate using this dataset. We derive a tight relation between the integrated stellar mass and the gas-phase abundance, with a dispersion smaller than the one already reported in the literature ($sigma_{Delta{rm log(O/H)}}=$0.07 dex). Indeed, this dispersion is only slightly larger than the typical error derived for our oxygen abundances. However, we do not find any secondary relation with the star-formation rate, other than the one induced due to the primary relation of this quantity with the stellar mass. We confirm the result using the $sim$3000 individual HII regions, for the corresponding local relations. Our results agree with the scenario in which gas recycling in galaxies, both locally and globally, is much faster than other typical timescales, like that of gas accretion by inflow and/or metal loss due to outflows. In essence, late-type/disk dominated galaxies seem to be in a quasi-steady situation, with a behavior similar to the one expected from an instantaneous recycling/closed-box model.
We present here the Calar Alto Legacy Integral Field Area (CALIFA) survey, which has been designed to provide a first step in this direction.We summarize the survey goals and design, including sample selection and observational strategy.We also showc
ase the data taken during the first observing runs (June/July 2010) and outline the reduction pipeline, quality control schemes and general characteristics of the reduced data. This survey is obtaining spatially resolved spectroscopic information of a diameter selected sample of $sim600$ galaxies in the Local Universe (0.005< z <0.03). CALIFA has been designed to allow the building of two-dimensional maps of the following quantities: (a) stellar populations: ages and metallicities; (b) ionized gas: distribution, excitation mechanism and chemical abundances; and (c) kinematic properties: both from stellar and ionized gas components. CALIFA uses the PPAK Integral Field Unit (IFU), with a hexagonal field-of-view of $sim1.3sqarcmin$, with a 100% covering factor by adopting a three-pointing dithering scheme. The optical wavelength range is covered from 3700 to 7000 {AA}, using two overlapping setups (V500 and V1200), with different resolutions: Rsim850 and Rsim1650, respectively. CALIFA is a legacy survey, intended for the community. The reduced data will be released, once the quality has been guaranteed. The analyzed data fulfill the expectations of the original observing proposal, on the basis of a set of quality checks and exploratory analysis. We conclude from this first look at the data that CALIFA will be an important resource for archaeological studies of galaxies in the Local Universe.
The Calar Alto Observatory, located at 2168m height above the sea level in continental Europe, holds a significant number of astronomical telescopes and experiments, covering a large range of the electromagnetic domain, from gamma-ray to near-infrare
d. It is a very well characterized site, with excellent logistics. Its main telescopes includes a large suite of instruments. At the present time, new instruments, namely CAFE, PANIC and Carmenes, are under development. We are also planning a new operational scheme in order to optimize the observatory resources.
A prototype of a low cost Adaptive Optics (AO) system has been developed at the Instituto de Astrofisica de Andalucia (CSIC) and tested at the 2.2m telescope of the Calar Alto observatory. We present here the status of the project, which includes the
image stabilization system and compensation of high order wavefront aberrations with a membrane deformable mirror. The image stabilization system consists of magnet driven tip-tilt mirror. The higher order compensation system comprises of a Shack-Hartmann sensor, a membrane deformable mirror with 39 actuators and the control computer that allows operations up to 420Hz in closed loop mode. We have successfully closed the high order AO loop on natural guide stars. An improvement of 4 times in terms of FWHM was achieved. The description and the results obtained on the sky are presented in this paper.
In this article we study the morphology, kinematics and ionization properties of the giant ionized gas nebulae surrounding two high redshift radio galaxies, 4C40.36 (z=2.27) and 4C48.48 (z=2.34).}{Integral Field Spectroscopy observations were taken u
sing the PPAK bundle of the PMAS spectrograph, mounted on the 3.5m on the Calar Alto Observatory, in order to cover a field-of-view of 64 X 72 centered in each radio galaxy. The observations spanned over 5 nights, using two different spectral resolutions (with FWHM~4 AA and ~8 AA respectively), covering the optical wavelength range from ~3700 AA to ~7100 AA, which corresponds to the rest-frame ultraviolet range from ~1100 AA to ~2000 AA >. Various emission lines are detected within this wavelength range, including Lyalpha (1216 AA), NV (1240 AA), CIV (1549 AA), HeII (1640 AA), OIII] (1663 AA) and CIII] (1909AA). The dataset was used to derive the spatial distribution of the flux intensity of each of these lines and the gas kinematics. The properties of the emission lines in the nuclear regions were studied in detail.In agreement with previous studies, we find that both objects are embedded in a large ionized gas nebula, where Ly alpha emission is extended across ~100 kpc or more. The CIV and HeII emission lines are also spatially extended. The nebulae are generally aligned with the radio axis, although we detect emission far from it. In 4C+48.48, there is a band of low Ly-alpha/CIV running perpendicular to the radio axis, at the location of the active nucleus. This feature might be the observational signature of an edge-on disk of neutral gas. The kinematics of both nebulae are inconsistent with stable rotation, although they are not inconsistent with infall or outflow.
