Bodo L. Ziegler

CALIFA, the Calar Alto Legacy Integral Field Area survey

We present the Calar Alto Legacy Integral Field Area survey (CALIFA). CALIFAs main aim is to obtain spatially resolved spectroscopic information for ~600 galaxies of all Hubble types in the Local Universe (0.005< z <0.03). The survey has been designed to allow three key measurements to be made: (a) Two-dimensional maps of stellar populations (star formation histories, chemical elements); (b) The distribution of the excitation mechanism and element abundances of the ionized gas; and (c) Kinematic properties (velocity ?elds, velocity dispersion), both from emission and from absorption lines. To cover the full optical extension of the target galaxies (i.e. out to a 3sigma depth of ~23 mag/arcsec2), CALIFA uses the exceptionally large ?eld of view of the PPAK/PMAS IFU at the 3.5m telescope of the Calar Alto observatory. We use two grating setups, one covering the wavelength range between 3700 and 5000 AA at a spectral resolution R~1650, and the other covering 4300 to 7000 AA at R~850. The survey was allocated 210 dark nights, distributed in 6 semesters and starting in July 2010 and is carried out by the CALIFA collaboration, comprising ~70 astronomers from 8 di?erent countries. As a legacy survey, the fully reduced data will be made publically available, once their quality has been veri?ed. We showcase here early results obtained from the data taken so far (21 galaxies).

Mass-metallicity relation explored with CALIFA - I. Is there a dependence on the star-formation rate?

We studied 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 a resolution high enough to separate individual H II regions and/or aggregations. About 3000 individual H II regions have been detected. The spectra cover the wavelength range between [OII]3727 and [SII]6731, with a sufficient signal-to-noise ratio to derive the oxygen abundance and star-formation rate associated with each region. In addition, we 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 lower than the one already reported in the literature (σ_Δlog (O/H) = 0.07 dex). Indeed, this dispersion is only slightly higher than the typical error derived for our oxygen abundances. However, we found no secondary relation with the star-formation rate other than the one induced by the primary relation of this quantity with the stellar mass. The analysis for our sample of ~3000 individual H II regions confirms (i) a local mass-metallicity relation and (ii) the lack of a secondary relation with the star-formation rate. The same analysis was performed with similar results for the specific star-formation rate. Our results agree with the scenario in which gas recycling in galaxies, both locally and globally, is much faster than other typical timescales, such 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.

Exploring Cluster Elliptical Galaxies as Cosmological Standard Rods

We explore the possibility of calibrating massive cluster elliptical galaxies as cosmological standard rods using the fundamental plane relation combined with a correction for luminosity evolution. Although cluster ellipticals certainly formed in a complex way, their passive evolution out to redshifts of about 1 indicates that basically all major merging and accretion events took place at higher redshifts. Therefore, a calibration of their luminosity evolution can be attempted. We propose to use the Mg-? relation for that purpose because it is independent of distance and cosmology. We discuss a variety of possible caveats, ranging from dynamical evolution to uncertainties in stellar population models and evolution corrections to the presence of age spread. Sources of major random and systematic errors are analyzed as well. We apply the described procedure to nine elliptical galaxies in two clusters at z = 0.375 and derive constraints on the cosmological model. For the best-fitting ?-free cosmological model we obtain q0 ? 0.1, with 90% confidence limits being 0 < q0 < 0.7 (the lower limit being due to the presence of matter in the universe). If the inflationary scenario applies (i.e., the universe has flat geometry), then, for the best-fitting model, matter and ? contribute about equally to the critical cosmic density (i.e., ?m ? ?? ? 0.5). With 90% confidence, ?? should be smaller than 0.9.

The Tully-Fisher relation at intermediate redshift

Using the Very Large Telescope in Multi Object Spectroscopy mode, we have observed a sample of 113 field spiral galaxies in the FORS Deep Field (FDF) with redshifts in the range 0.1< z< 1.0. The galaxies were selected based on apparent brightness (R< 23 m ) and encompass all late spectrophotometric types from Sa to Sdm/Im. Spatially resolved rotation curves have been extracted for 77 galaxies and fitted with synthetic velocity fields taking into account all observational e ffects from inclination and slit misalignment to seeing and slit width. We also compared different shapes for the intrinsic rotation curve. To obtain robust values of Vmax, our analysis is focused on galaxies with rotation curves th at extend well into the region of constant rotation velocity at large radii. If the slope of th e local Tully-Fisher relation (TFR) is held fixed, we find evid ence for a mass-dependent luminosity evolution which is as large as up toMB≈ −2 m for the lowest-mass galaxies, but is small or even negligible for the highest-mass systems in our sample. In effect, the TFR slope is shallower at z≈ 0.5 in comparison to the local sample. We argue for a mass-dependent evolution of the mass-to-light ratio. An additional population of blue, low-mass spirals does not seem a very appealing explanation. The flatter tilt we find for the distant TFR is in contradictio n to the predictions of recent semi-analytic simulations.

The ionized gas in the CALIFA early-type galaxies - I. Mapping two representative cases: NGC 6762 and NGC 5966

As part of the ongoing CALIFA survey, we have conducted a thorough bidimensional analysis of the ionized gas in two E/S0 galaxies, NGC 6762 and NGC 5966, aiming to shed light on the nature of their warm ionized ISM. Specifically, we present optical (3745–7300 A) integral field spectroscopy obtained with the PMAS/PPAK integral field spectrophotometer. Its wide field-of-view (1′ × 1′) covers the entire optical extent of each galaxy down to faint continuum surface brightnesses. To recover the nebular lines, we modeled and subtracted the underlying stellar continuum from the observed spectra using the STARLIGHT spectral synthesis code. The pure emission-line spectra were used to investigate the gas properties and determine the possible sources of ionization. We show the advantages of IFU data in interpreting the complex nature of the ionized gas in NGC 6762 and NGC 5966. In NGC 6762, the ionized gas and stellar emission display similar morphologies, while the emission line morphology is elongated in NGC 5966, spanning ~6 kpc, and is oriented roughly orthogonal to the major axis of the stellar continuum ellipsoid. Whereas gas and stars are kinematically aligned in NGC 6762, the gas is kinematically decoupled from the stars in NGC 5966. A decoupled rotating disk or an “ionization cone” are two possible interpretations of the elongated ionized gas structure in NGC 5966. The latter would be the first “ionization cone” of such a dimension detected within a weak emission-line galaxy. Both galaxies have weak emission-lines relative to the continuum[EW(Hα) ≲ 3 A] and have very low excitation, log([OIII]λ5007/Hβ) ≲ 0.5. Based on optical diagnostic ratios ([OIII]λ5007/Hβ, [NII]λ6584/Hα, [SII]λ6717, 6731/Hα, [OI]λ6300/Hα), both objects contain a LINER nucleus and an extended LINER-like gas emission. The emission line ratios do not vary significantly with radius or aperture, which indicates that the nebular properties are spatially homogeneous. The gas emission in NGC 6762 can be best explained by photoionization by pAGB stars without the need of invoking any other excitation mechanism. In the case of NGC 5966, the presence of a nuclear ionizing source seems to be required to shape the elongated gas emission feature in the “ionization cone” scenario, although ionization by pAGB stars cannot be ruled out. Further study of this object is needed to clarify the nature of its elongated gas structure.

Redshift Evolution of the Stellar Populations in Elliptical Galaxies

Velocity dispersions σ and Mg absorption line strengths Mgb have been measured for a sample of 16 ellipticals in three clusters at a redshift of 0.37. Like local cluster ellipticals, these objects show a correlation between Mgb and σ. However, at any given σ, the mean Mgb of the ellipticals at z = 0.37 is weaker than the mean Mgb of their local relatives in the Coma and Virgo clusters. The Mgb weakening is smallest for the most luminous ellipticals and larger for the fainter objects. This is unambiguous evidence for small but significant passive evolution of the stellar populations of elliptical galaxies with redshift. It requires that the bulk of the stars in cluster ellipticals has formed at z > 2. The most luminous objects may even have formed at z > 4. The Mgb-σ test is a very reliable estimator for the evolution of old stellar populations because it is virtually independent from the stellar initial mass function (IMF) and from the metallicities of the galaxies. Furthermore, the influence of selection effects is minimal. Consistent with the weakening of Mgb we find evidence for a B-band luminosity evolution of about 0.5 ± 0.1 mag at z = 0.37 from the Faber-Jackson relation. The combined information about the evolution of Mgb and luminosity allows us to constrain both the slope of the IMF in ellipticals and the cosmological deceleration parameter q0. Our present measurements are compatible with a standard Salpeter IMF and a q0 of 0.5 ± 0.5.

The Evolution of the Tully-Fisher Relation of Spiral Galaxies*

We present the B-band Tully-Fisher relation (TFR) of 60 late-type galaxies with redshifts 0.1–1. The galaxies were selected from the FORS Deep Field with a limiting magnitude of . Spatially resolved rotation curves R p 23 were derived from spectra obtained with FORS2 at the Very Large Telescope. High-mass galaxies with vmax 150 km s 1 show little evolution, whereas the least massive systems in our sample are brighter by ∼1–2 mag compared with their local counterparts. For the entire distant sample, the TFR slope is flatter than for local field galaxies ( vs. ). Thus, we find evidence for the evolution of the slope of the TFR 5.77 0.45 7.92 0.18 with redshift on the 3 j level. This is still true when we subdivide the sample into three redshift bins. We speculate that the flatter tilt of our sample is caused by the evolution of luminosities and an additional population of blue galaxies at . The mass dependence of the TFR evolution also leads to variations for different z 0.2 galaxy types in magnitude-limited samples, suggesting that selection effects can account for the discrepant results of previous TFR studies on the luminosity evolution of late-type galaxies. Subject headings: galaxies: evolution — galaxies: kinematics and dynamics — galaxies: spiral

The FORS Deep Field: Field selection, photometric observations and photometric catalog ,

The FORS Deep Field project is a multi-colour, multi-object spectroscopic investigation of a ∼7 � × 7 � region near the south galactic pole based mostly on observations carried out with the FORS instruments attached to the VLT telescopes. It includes the QSO Q 0103-260 (z = 3.36). The goal of this study is to improve our understanding of the formation and evolution of galaxies in the young Universe. In this paper the field selection, the photometric observations, and the data reduction are described. The source detection and photometry of objects in the FORS Deep Field is discussed in detail. A combined B and I selected UBgRIJKsphotometric catalog of 8753 objects in the FDF is presented and its properties are briefly discussed. The formal 50% completeness limits for point sources, derived from the co-added images, are 25.64, 27.69, 26.86, 26.68, 26.37, 23.60 and 21.57 in U, B, g, R, I, J and Ks(Vega-system), respectively. A comparison of the number counts in the FORS Deep Field to those derived in other deep field surveys shows very good agreement.

CALIFA, the Calar Alto Legacy Integral Field Area survey IV. Third public data release

We present a dynamical classification system for galaxies based on the shapes of their circular velocity curves (CVCs). We derive the CVCs of 40 SAURON and 42 CALIFA galaxies across Hubble sequence via a full line-of-sight integration as provided by solutions of the axisymmetric Jeans equations. We use Principal Component Analysis (PCA) applied to the circular curve shapes to find characteristic features and use a k-means classifier to separate circular curves into classes. This objective classification method identifies four different classes, which we name Slow-Rising (SR), Flat (F), Sharp-Peaked (SP) and Round-Peaked (RP) circular curves. SR-CVCs are mostly represented by late-type spiral galaxies (Scd-Sd) with no prominent spheroids in the central parts and slowly rising velocities; F-CVCs span almost all morphological types (E,S0,Sab,Sb-Sbc) with flat velocity profiles at almost all radii; SP-CVCs are represented by early-type and early-type spiral galaxies (E,S0,Sb-Sbc) with prominent spheroids and sharp peaks in the central velocities. RP-CVCs are represented by only two morphological types (E,Sa-Sab) with prominent spheroids, but RP-CVCs have much rounder peaks in the central velocities than SP-CVCs. RP-CVCs are typical for high-mass galaxies, while SR-CVCs are found for low-mass galaxies. Intermediate-mass galaxies usually have F-CVCs and SP-CVCs. Circular curve classification presents an alternative to typical morphological classification and may be more tightly linked to galaxy evolution.This paper describes the Third Public Data Release (DR3) of the Calar Alto Legacy Integral Field Area (CALIFA) survey. Science-grade quality data for 667 galaxies are made public, including the 200 galaxies of the Second Public Data Release (DR2). Data were obtained with the integral-field spectrograph PMAS/PPak mounted on the 3.5m telescope at the Calar Alto Observatory. Three different spectral setups are available, i) a low-resolution V500 setup covering the wavelength range 3749-7500 AA (4240-7140 AA unvignetted) with a spectral resolution of 6.0 AA (FWHM), for 646 galaxies, ii) a medium-resolution V1200 setup covering the wavelength range 3650-4840 AA (3650-4620 AA unvignetted) with a spectral resolution of 2.3 AA (FWHM), for 484 galaxies, and iii) the combination of the cubes from both setups (called COMBO), with a spectral resolution of 6.0 AA and a wavelength range between 3700-7500 AA (3700-7140 AA unvignetted), for 446 galaxies. The Main Sample, selected and observed according to the CALIFA survey strategy covers a redshift range between 0.005 and 0.03, spans the color-magnitude diagram and probes a wide range of stellar mass, ionization conditions, and morphological types. The Extension Sample covers several types of galaxies that are rare in the overall galaxy population and therefore not numerous or absent in the CALIFA Main Sample. All the cubes in the data release were processed using the latest pipeline, which includes improved versions of the calibration frames and an even further improved im- age reconstruction quality. In total, the third data release contains 1576 datacubes, including ~1.5 million independent spectra. It is available at this http URL

Nebular emission and the Lyman continuum photon escape fraction in CALIFA early-type galaxies

PP is supported by Ciencia 2008 Contract, funded by FCT/MCTES (Portugal) and POPH/FSE (EC), and J.M.G. by a Post-Doctoral grant, funded by FCT/MCTES (Portugal) and POPH/FSE (EC). P.P. and J.M.G. acknowledge support by the Fundacao para a Ciencia e a Tecnologia (FCT) under project FCOMP-01-0124-FEDER-029170 (Reference FCT PTDC/FIS-AST/3214/2012), funded by FCT-MEC (PIDDAC) and FEDER (COMPETE). I.M. acknowledges support from Spanish grant AYA2010-15169 and the Junta de Andalucia through TIC-114 and the Excellence Project P08-TIC-03531. J.F.-B. from the Ramon y Cajal Program, grants AYA2010-21322-C03-02 and AIB-2010-DE-00227 from the Spanish Ministry of Economy and Competitiveness (MINECO), as well as from the FP7 Marie Curie Actions of the European Commission, via the Initial Training Network DAGAL under REA grant agreement n° 289313.