Abundance patterns in early-type galaxies: is there a “knee” in the [Fe/H] vs. [<i>α</i>/Fe] relation?

Walcher, C. J.; Coelho, P.; Gallazzi, Anna; Bruzual, G.; Charlot, S.; Chiappini, Cristina

doi:10.1051/0004-6361/201525924

Cited by 56 publications

(50 citation statements)

References 120 publications

(180 reference statements)

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“…2 we show the complete kinematics maps, produced by the software PyParadise (Husemann et al 2016, Husemann et al in prep. ), which is an improved version of Paradise (Walcher et al 2015). The left panel of Fig.…”

Section: Velocities and Velocity Mapsmentioning

confidence: 99%

The globular cluster system of NGC 1316

Richtler

Hilker

Puzia

et al. 2017

A&A

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Context. The light of the merger remnant NGC 1316 (Fornax A) is dominated by old and intermediate-age stars. The only sign of current star formation in this big galaxy is the HII region SH2, an isolated star cluster complex with a ring-like morphology and an estimated age of 0.1 Gyr at a galactocentric distance of about 35 kpc. A nearby intermediate-age globular cluster, surrounded by weak line emission and a few more young star clusters, is kinematically associated. The origin of this complex is enigmatic. Aims. We want to investigate the nature of this star cluster complex. The nebular emission lines permit a metallicity determination which can discriminate between a dwarf galaxy or other possible precursors. Methods. We used the Integrated Field Unit (IFU) of the VIMOS instrument at the Very Large Telescope of the European Southern Observatory in high dispersion mode to study the morphology, kinematics, and metallicity employing line maps, velocity maps, and line diagnostics of a few characteristic spectra. Results. The line ratios of different spectra vary, indicating highly structured HII regions, but define a locus of uniform metallicity. The strong-line diagnostic diagrams and empirical calibrations point to a nearly solar or even super-solar oxygen abundance. The velocity dispersion of the gas is highest in the region offset from the bright clusters. Star formation may be active on a low level. There is evidence for a large-scale disk-like structure in the region of SH2, which would make the similar radial velocity of the nearby globular cluster easier to understand. Conclusions. The high metallicity does not fit to a dwarf galaxy as progenitor. We favour the scenario of a free-floating gaseous complex having its origin in the merger 2 Gyr ago. Over a long period the densities increased secularly until finally the threshold for star formation was reached. SH2 illustrates how massive star clusters can form outside starbursts and without a considerable field population.

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Section: Velocities and Velocity Mapsmentioning

confidence: 99%

The globular cluster system of NGC 1316

Richtler

Hilker

Puzia

et al. 2017

A&A

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“…We then estimated the velocities for each bin by fitting model template spectra from the full INDO-US template library (Valdes et al 2004) to the observed spectra using the code PyParadise (Husemann et al 2016) which is an extended Python version of paradise (Walcher et al 2015). We refer the reader to these references for the details of the algorithm.…”

Section: Velocity Dispersion Measurementmentioning

confidence: 99%

A combined photometric and kinematic recipe for evaluating the nature of bulges using the CALIFA sample

Neumann

Wisotzki

Choudhury

et al. 2017

A&A

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Understanding the nature of bulges in disc galaxies can provide important insights into the formation and evolution of galaxies. For instance, the presence of a classical bulge suggests a relatively violent history, in contrast, the presence of simply an inner disc (also referred to as a "pseudobulge") indicates the occurrence of secular evolution processes in the main disc. However, we still lack criteria to effectively categorise bulges, limiting our ability to study their impact on the evolution of the host galaxies. Here we present a recipe to separate inner discs from classical bulges by combining four different parameters from photometric and kinematic analyses: The bulge Sérsic index n b , the concentration index C 20,50 , the Kormendy (1977) relation and the inner slope of the radial velocity dispersion profile ∇σ. With that recipe we provide a detailed bulge classification for a sample of 45 galaxies from the integral-field spectroscopic survey CALIFA. To aid in categorising bulges within these galaxies, we perform 2D image decomposition to determine bulge Sérsic index, bulge-to-total light ratio, surface brightness and effective radius of the bulge and use growth curve analysis to derive a new concentration index, C 20,50 . We further extract the stellar kinematics from CALIFA data cubes and analyse the radial velocity dispersion profile. The results of the different approaches are in good agreement and allow a safe classification for approximately 95% of the galaxies. In particular, we show that our new "inner" concentration index performs considerably better than the traditionally used C 50,90 when yielding the nature of bulges. We also found that a combined use of this index and the Kormendy (1977) relation gives a very robust indication of the physical nature of the bulge.

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“…These methods can provide constraints on different physical properties, either exploiting a pixel-by-pixel fit to the spectrum (e.g. Cappellari & Emsellem 2004;Cid Fernandes et al 2005a;Ocvirk et al 2006;Walcher et al 2015) or interpreting single or few spectral features, for instance the emission line luminosity (Kennicutt 1998), emission line ratios (Kobulnicky & Kewley 2004), Lick absorption indices (Gallazzi et al 2005) or the 4000Å break (Bruzual A. 1983).…”

Section: Introductionmentioning

confidence: 99%

Physical properties of galaxies: towards a consistent comparison between hydrodynamical simulations and SDSS

Guidi

Scannapieco

Walcher

et al. 2016

Mon. Not. R. Astron. Soc.

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We study the effects of applying observational techniques to derive the properties of simulated galaxies, with the aim of making an unbiased comparison between observations and simulations. For our study, we used fifteen galaxies simulated in a cosmological context using three different feedback and chemical enrichment models, and compared their z = 0 properties with data from the Sloan Digital Sky Survey (SDSS). We show that the physical properties obtained directly from the simulations without post-processing can be very different to those obtained mimicking observational techniques. In order to provide simulators a way to reliably compare their galaxies with SDSS data, for each physical property that we studied -colours, magnitudes, gas and stellar metallicities, mean stellar ages and star formation rates -we give scaling relations that can be easily applied to the values extracted from the simulations; these scalings have in general a high correlation, except for the gas oxygen metallicities. Our simulated galaxies are photometrically similar to galaxies in the blue sequence/green valley, but in general they appear older, passive and with lower metal content compared to most of the spirals in SDSS. As a careful assessment of the agreement/disagreement with observations is the primary test of the baryonic physics implemented in hydrodynamical codes, our study shows that considering the observational biases in the derivation of the galaxies' properties is of fundamental importance to decide on the failure/success of a galaxy formation model.

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Abundance patterns in early-type galaxies: is there a “knee” in the [Fe/H] vs. [α/Fe] relation?

Cited by 56 publications

References 120 publications

The globular cluster system of NGC 1316

The globular cluster system of NGC 1316

A combined photometric and kinematic recipe for evaluating the nature of bulges using the CALIFA sample

Physical properties of galaxies: towards a consistent comparison between hydrodynamical simulations and SDSS

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