arXiv subjects

A. L. de Amorim

Publications and source records attributed to A. L. de Amorim.

At least 19 recordsLinked to original sources

arXiv2022

The DIVING$^{3D}$ Survey -- Deep IFS View of Nuclei of Galaxies -- I. Definition and Sample Presentation

We present the Deep Integral Field Spectrograph View of Nuclei of Galaxies (DIVING$^{3D}$) survey, a seeing-limited optical 3D spectroscopy study of the central regions of all 170 galaxies in the Southern hemisphere with B < 12.0 and |b| > 15 degrees. Most of the observations were taken with the Integral Field Unit of the Gemini Multi-Object Spectrograph, at the Gemini South telescope, but some are also being taken with the Southern Astrophysical Research Telescope (SOAR) Integral Field Spectrograph. The DIVING$^{3D}$ survey was designed for the study of nuclear emission-line properties, circumnuclear (within scales of hundreds of pc) emission-line properties, stellar and gas kinematics and stellar archaeology. The data have a combination of high spatial and spectral resolution not matched by previous surveys and will result in significant contributions for studies related to, for example, the statistics of low-luminosity active galactic nuclei, the ionization mechanisms in Low-Ionization Nuclear Emission-Line Regions, the nature of transition objects, among other topics.

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arXiv2021

The Fornax Cluster through S-PLUS

The Southern Photometric Local Universe Survey (S-PLUS) aims to map $\approx$ 9300 deg$^2$ of the Southern sky using the Javalambre filter system of 12 optical bands, 5 Sloan-like filters and 7 narrow-band filters centered on several prominent stellar features ([OII], Ca H+K, D4000, H$_δ$, Mgb, H$_α$ and CaT). S-PLUS is carried out with the T80-South, a new robotic 0.826-m telescope located on CTIO, equipped with a wide FoV camera (2 deg$^2$). In this poster we introduce project #59 of the S-PLUS collaboration aimed at studying the Fornax galaxy cluster covering an sky area of $\approx$ 11 $\times$ 7 deg$^2$, and with homogeneous photometry in the 12 optical bands of S-PLUS (Coordinator: A. Smith Castelli).

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arXiv2020

The miniJPAS survey: star-galaxy classification using machine learning

Future astrophysical surveys such as J-PAS will produce very large datasets, which will require the deployment of accurate and efficient Machine Learning (ML) methods. In this work, we analyze the miniJPAS survey, which observed about 1 deg2 of the AEGIS field with 56 narrow-band filters and 4 ugri broad-band filters. We discuss the classification of miniJPAS sources into extended (galaxies) and point-like (e.g. stars) objects, a necessary step for the subsequent scientific analyses. We aim at developing an ML classifier that is complementary to traditional tools based on explicit modeling. In order to train and test our classifiers, we crossmatched the miniJPAS dataset with SDSS and HSC-SSP data. We trained and tested 6 different ML algorithms on the two crossmatched catalogs. As input for the ML algorithms we use the magnitudes from the 60 filters together with their errors, with and without the morphological parameters. We also use the mean PSF in the r detection band for each pointing. We find that the RF and ERT algorithms perform best in all scenarios. When analyzing the full magnitude range of 15 21). We use our best classifiers, with and without morphology, in order to produce a value added catalog available at https://j-pas.org/datareleases .

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arXiv2020

Less than the sum of its parts: the dust-corrected H$α$ luminosity of star-forming galaxies explored at different spatial resolutions with MaNGA and MUSE

The H$α$ and H$β$ emission line luminosities measured in a single integrated spectrum are affected in non-trivial ways by point-to-point variations in dust attenuation in a galaxy. This work investigates the impact of this variation when estimating global H$α$ luminosities corrected for the presence of dust by a global Balmer decrement. Analytical arguments show that the dust-corrected H$α$ luminosity is always underestimated when using the global H$α$/H$β$ flux ratio to correct for dust attenuation. We measure this effect on 156 face-on star-forming galaxies from the Mapping Nearby Galaxies at APO (MaNGA) survey. At 1-2 kpc spatial resolution, the effect is small but systematic, with the integrated dust-corrected H$α$ luminosity underestimated by $2$-$4$ per cent (and typically not more than by $10$ per cent), and depends on the specific star formation rate of the galaxy. Given the spatial resolution of MaNGA, these are lower limits for the effect. From Multi Unit Spectroscopic Explorer (MUSE) observations of NGC 628 with a resolution of 36 pc we find the discrepancy between the globally and the point-by-point dust-corrected H$α$ luminosity to be $14 \pm 1$ per cent, which may still underestimate the true effect. We use toy models and simulations to show that the true difference depends strongly on the spatial variance of the H$α$/H$β$ flux ratio, and on the slope of the relation between H$α$ luminosity and dust attenuation within a galaxy. Larger samples of higher spatial resolution observations are required to quantify the dependence of this effect as a function of galaxy properties.

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arXiv2020

The miniJPAS survey: a preview of the Universe in 56 colours

The Javalambre-Physics of the Accelerating Universe Astrophysical Survey (J-PAS) will soon start to scan thousands of square degrees of the northern extragalactic sky with a unique set of $56$ optical filters from a dedicated $2.55$m telescope, JST, at the Javalambre Astrophysical Observatory. Before the arrival of the final instrument (a 1.2 Gpixels, 4.2deg$^2$ field-of-view camera), the JST was equipped with an interim camera (JPAS-Pathfinder), composed of one CCD with a 0.3deg$^2$ field-of-view and resolution of 0.23 arcsec pixel$^{-1}$. To demonstrate the scientific potential of J-PAS, with the JPAS-Pathfinder camera we carried out a survey on the AEGIS field (along the Extended Groth Strip), dubbed miniJPAS. We observed a total of $\sim 1$ deg$^2$, with the $56$ J-PAS filters, which include $54$ narrow band (NB, $\rm{FWHM} \sim 145$Angstrom) and two broader filters extending to the UV and the near-infrared, complemented by the $u,g,r,i$ SDSS broad band (BB) filters. In this paper we present the miniJPAS data set, the details of the catalogues and data access, and illustrate the scientific potential of our multi-band data. The data surpass the target depths originally planned for J-PAS, reaching $\rm{mag}_{\rm {AB}}$ between $\sim 22$ and $23.5$ for the NB filters and up to $24$ for the BB filters ($5σ$ in a $3$~arcsec aperture). The miniJPAS primary catalogue contains more than $64,000$ sources extracted in the $r$ detection band with forced photometry in all other bands. We estimate the catalogue to be complete up to $r=23.6$ for point-like sources and up to $r=22.7$ for extended sources. Photometric redshifts reach subpercent precision for all sources up to $r=22.5$, and a precision of $\sim 0.3$% for about half of the sample. (Abridged)

astro-ph.CO↗

arXiv2019

Diffuse ionized gas and its effects on nebular metallicity estimates of star-forming galaxies

We investigate the impact of the diffuse ionized gas (DIG) on abundance determinations in star-forming (SF) galaxies. The DIG is characterised using the H$α$ equivalent width ($W_{\text{H}α}$). From a set of 1,409 SF galaxies from the Mapping Nearby Galaxies at APO (MaNGA) survey, we calculate the fractional contribution of the DIG to several emission lines using high-$S/N$ data from SF spaxels (instead of using noisy emission-lines in DIG-dominated spaxels). Our method is applicable to spectra with observed $W_{\text{H}α} \gtrsim 10$ angstroms (which are not dominated by DIG emission). Since the DIG contribution depends on galactocentric distance, we provide DIG-correction formulae for both entire galaxies and single aperture spectra. Applying those to a sample of $\,> 90,000$ SF galaxies from the Sloan Digital Sky Survey, we find the following. (1) The effect of the DIG on strong-line abundances depends on the index used. It is negligible for the ([O III]/H$β$)/([N II]/H$α$) index, but reaches $\sim 0.1$ dex at the high-metallicity end for [N II]/H$α$. (2) This result is based on the $\sim$kpc MaNGA resolution, so the real effect of the DIG is likely greater. (3) We revisit the mass-metallicity-star formation rate (SFR) relation by correcting for the DIG contribution in both abundances and SFR. The effect of DIG removal is more prominent at higher stellar masses. Using the [N II]/H$α$ index, O/H increases with SFR at high stellar mass, contrary to previous claims.

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arXiv2018

Spatially resolved mass-to-light from the CALIFA survey. Mass-to-light ratio vs. color relations

We investigated the mass-to-light versus color relations (MLCRs) derived from the spatially resolved star formation history of a sample of 452 galaxies observed with integral field spectroscopy in the CALIFA survey. We derived the stellar mass ($M_\star$) and the stellar mass surface density from the combination of full spectral fitting (using different sets of stellar population models) with observed and synthetic colors in optical broad bands. This method allows obtaining the radial structure of the mass-to-light ratio ($M/L$) at several wavelengths and studying the spatially resolved MLCRs. Our sample covers a wide range of Hubble types from Sc to E, with stellar masses ranging from $M_\star \sim 10^{8.4}$ to $10^{12}$ M$_\odot$. The scatter in the MLCRs was studied as a function of morphology, stellar extinction, and emission line contribution to the colors. The effects of the initial mass function (IMF) and stellar population models in the MLCRs were also explored. Our main results are that (a) the $M/L$ ratio has a negative radial gradient that is steeper within the central 1 half-light-radius (HLR). It is steeper in Sb-Sbc than in early-type galaxies. (b) The MLCRs between $M/L$ and optical colors were derived with a scatter of $\sim$ 0.1 dex. Extinction and emission line contributions do not affect the scatter of these relations. Morphology does not produce a significant effect, except if the general relation is used for galaxies redder than $(u-i) > 4$ or bluer than $(u-i) < 0$. (c) The IMF has a large effect on MLCRs, as expected. The change from a Chabrier to a Salpeter IMF produces a median shift of $\sim$ \oimf\ dex when mass loss from stellar evolution is also taken into account. (d) These MLCRs are in agreement with previous results, in particular for relations with $g$ and $r$ bands and the $B$ and $V$ Johnson systems. FITS tables available at http://pycasso.iaa.es/ML

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arXiv2017

Diffuse ionized gas in galaxies across the Hubble sequence at the CALIFA resolution

We use spatially resolved spectroscopy from the Calar Alto Legacy Field Area (CALIFA) survey to study the nature of the line emitting gas in galaxies of different Hubble types, focusing on the separation of star-forming (SF) regions from those better characterized as diffuse ionized gas (DIG). The diagnosis is carried out in terms of the equivalent width of ${\rm H}α$ ($W_{{\rm H}α}$). Three nebular regimes are identified. Regions where $W_{{\rm H}α} < 3\ Å$ define what we call the hDIG, the component of the DIG where photoionization is dominated by hot, low-mass, evolved stars. Regions where $W_{{\rm H}α} > 14\ Å$ trace SF complexes. $W_{{\rm H}α}$ values in the intermediate 3--14 $Å$ range reflect a mixed regime (mDIG) where more than one process contributes. This three-tier scheme is inspired both by theoretical and empirical considerations. Its application to CALIFA galaxies of different types and inclinations leads to the following results: $\textit{(i)}$ the hDIG component is prevalent throughout ellipticals and S0's as well as in bulges, and explains the strongly bimodal distribution of $W_{{\rm H}α}$ both among and within galaxies. $\textit{(ii)}$ Early-type spirals have some hDIG in their discs, but this component becomes progressively less relevant for later Hubble types. $\textit{(iii)}$ hDIG emission is also present above and below galactic discs, as seen in several edge-on spirals in our sample. $\textit{(iv)}$ The SF/mDIG proportion grows steadily from early- to late-type spirals, and from inner to outer radii. $\textit{(v)}$ Besides circumventing basic inconsistencies in conventional DIG/SF separation criteria based on the ${\rm H}α$ surface brightness, our $W_{{\rm H}α}$-based method produces results in agreement with a classical excitation diagram analysis.

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arXiv2017

The spatially resolved star formation history of CALIFA galaxies: Cosmic time scales

This paper presents the mass assembly time scales of nearby galaxies observed by CALIFA at the 3.5m telescope in Calar Alto. We apply the fossil record method of the stellar populations to the complete sample of the 3rd CALIFA data release, with a total of 661 galaxies, covering stellar masses from 10$^{8.4}$ to 10$^{12}$ M$_{\odot}$ and a wide range of Hubble types. We apply spectral synthesis techniques to the datacubes and process the results to produce the mass growth time scales and mass weighted ages, from which we obtain temporal and spatially resolved information in seven bins of galaxy morphology and six bins of stellar mass (M$_{\star}$) and stellar mass surface density ($Σ_{\star}$). We use three different tracers of the spatially resolved star formation history (mass assembly curves, ratio of half mass to half light radii, and mass-weighted age gradients) to test if galaxies grow inside-out, and its dependence with galaxy stellar mass, $Σ_{\star}$, and morphology. Our main results are as follows: (a) The innermost regions of galaxies assemble their mass at an earlier time than regions located in the outer parts; this happens at any given M$_{\star}$, $Σ_{\star}$, or Hubble type, including the lowest mass systems. (b) Galaxies present a significant diversity in their characteristic formation epochs for lower-mass systems. This diversity shows a strong dependence of the mass assembly time scales on $Σ_{\star}$ and Hubble type in the lower-mass range (10$^{8.4}$ to 10$^{10.4}$), but a very mild dependence in higher-mass bins. (c) All galaxies show negative $\langle$log age$\rangle_{M}$ gradients in the inner 1 HLR. The profile flattens with increasing values of $Σ_{\star}$. There is no significant dependence on M$_{\star}$ within a particular $Σ_{\star}$ bin, except for the lowest bin, where the gradients becomes steeper.

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arXiv2017

The spatially resolved star formation history of mergers: A comparative study of the LIRGs IC1623, NGC6090, NGC2623, and Mice

This paper presents the spatially resolved star formation history (2D-SFH) of a small sample of four local mergers: the early-stage mergers IC1623, NGC6090, and the Mice, and the more advanced merger NGC2623, by analyzing IFS data from the CALIFA survey and PMAS in LArr mode. Full spectral fitting techniques are applied to the datacubes to obtain the spatially resolved mass growth histories, the time evolution of the star formation rate intensity ($Σ_{SFR}$), and the local specific star formation rate, over three different timescales (30 Myr, 300 Myr, and 1 Gyr). The results are compared with non-interacting Sbc--Sc galaxies, to quantify if there is an enhancement of the star formation and to trace its time scale and spatial extent. Our results for the three LIRGs (IC1623W, NGC6090, and NGC2623) show that a major phase of star formation is occurring in time scales of 10$^{7}$ yr to few 10$^{8}$ yr, with global SFR enhancements of $\sim$2--6 with respect to main-sequence star forming (MSSF) galaxies. In the two early-stage mergers IC1623W and NGC6090, which are between first pericenter passage and coalescence, the most remarkable increase of the SFR with respect to non-interacting spirals occurred in the last 30 Myr, and it is spatially extended, with enhancements of factors 2--7 both in the centres ($r <$ 0.5 half light radius, HLR), and in the disks ($r >$ 1 HLR). In the more advanced merger NGC 2623 an extended phase of star formation occurred on a longer time-scale of $\sim$1 Gyr, with a SFR enhancement of a factor $\sim$2--3 larger than the one in Sbc--Sc MSSF galaxies over the same period, probably relic of the first pericenter passage epoch. A SFR enhancement in the last 30 Myr is also present, but only in NGC2623 centre, by a factor 3. In general, the spatially resolved SFHs of the LIRG-mergers are consistent with the predictions from high spatial resolution simulations.

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arXiv2017

The PyCASSO database: Spatially resolved stellar population properties for CALIFA galaxies

The Calar Alto Legacy Integral Field Area (CALIFA) survey, a pioneer in integral field spectroscopy legacy projects, has fostered many studies exploring the information encoded on the spatially resolved data on gaseous and stellar features in the optical range of galaxies. We describe a value-added catalogue of stellar population properties for CALIFA galaxies analysed with the spectral synthesis code STARLIGHT and processed with the PyCASSO platform. Our public data base (http://pycasso.ufsc.br/, mirror at http://pycasso.iaa.es/) comprises 445 galaxies from the CALIFA Data Release 3 with COMBO data. The catalogue provides maps for the stellar mass surface density, mean stellar ages and metallicities, stellar dust attenuation, star formation rates, and kinematics. Example applications both for individual galaxies and for statistical studies are presented to illustrate the power of this data set. We revisit and update a few of our own results on mass density radial profiles and on the local mass-metallicity relation. We also show how to employ the catalogue for new investigations, and show a pseudo Schmidt-Kennicutt relation entirely made with information extracted from the stellar continuum. Combinations to other databases are also illustrated. Among other results, we find a very good agreement between star formation rate surface densities derived from the stellar continuum and the $\mathrm{H}α$ emission. This public catalogue joins the scientific community's effort towards transparency and reproducibility, and will be useful for researchers focusing on (or complementing their studies with) stellar properties of CALIFA galaxies.

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arXiv2017

The spatially-resolved star formation histories of CALIFA galaxies: Implications for galaxy formation

This paper presents the spatially resolved star formation history (SFH) of nearby galaxies with the aim of furthering our understanding of the different processes involved in the formation and evolution of galaxies. To this end, we apply the fossil record method of stellar population synthesis to a rich and diverse data set of 436 galaxies observed with integral field spectroscopy in the CALIFA survey. The sample covers a wide range of Hubble types, with stellar masses ranging from $M_\star \sim 10^9$ to $7 \times 10^{11} M_\odot$. Spectral synthesis techniques are applied to the datacubes to retrieve the spatially resolved time evolution of the star formation rate (SFR), its intensity ($Σ_{\rm SFR}$), and other descriptors of the 2D-SFH in seven bins of galaxy morphology (E, S0, Sa, Sb, Sbc, Sc, and Sd), and five bins of stellar mass. Our main results are: a) Galaxies form very fast independently of their current stellar mass, with the peak of star formation at high redshift ($z > 2$). Subsequent star formation is driven by $M_\star$ and morphology, with less massive and later type spirals showing more prolonged periods of star formation. b) At any epoch in the past the SFR is proportional to $M_\star$, with most massive galaxies having the highest absolute (but lowest specific) SFRs. c) While nowadays $Σ_{\rm SFR}$ is similar for all spirals, and significantly lower in early type galaxies (ETG), in the past $Σ_{\rm SFR}$ scales well with morphology. The central regions of today's ETGs are where $Σ_{\rm SFR}$ reached the highest values ($> 10^3 \,M_\odot\,$Gyr$^{-1}\,$pc$^{-2}$), similar to those measured in high redshift star forming galaxies. d) The evolution of $Σ_{\rm SFR}$ in Sbc systems matches that of models for Milky-Way-like galaxies, suggesting that the formation of a thick disk may be a common phase in spirals at early epochs.

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arXiv2017

The spatially resolved stellar population and ionized gas properties in the merger LIRG NGC 2623

We report on a detailed study of the stellar populations and ionized gas properties in the merger LIRG NGC 2623, analysing optical Integral Field Spectroscopy from the CALIFA survey and PMAS LArr, multiwavelength HST imaging, and OSIRIS narrow band H$α$ and [NII]$λ$6584 imaging. The spectra were processed with the STARLIGHT full spectral fitting code, and the results compared with those for two early-stage merger LIRGs (IC 1623 W and NGC 6090), together with CALIFA Sbc/Sc galaxies. We find that NGC 2623 went through two periods of increased star formation (SF), a first and widespread episode, traced by intermediate-age stellar populations ISP (140 Myr-1.4 Gyr), and a second one, traced by young stellar populations YSP ($<$140 Myr), which is concentrated in the central regions ($<$1.4 kpc). Our results are in agreement with the epochs of the first peri-center passage ($\sim$200 Myr ago) and coalescence ($<$100 Myr ago) predicted by dynamical models, and with high resolution merger simulations in the literature, consistent with NGC 2623 representing an evolved version of the early-stage mergers. Most ionized gas is concentrated within $<$2.8 kpc, where LINER-like ionization and high velocity dispersion ($\sim$220 km/s) are found, consistent with the previously reported outflow. As revealed by the highest resolution OSIRIS and HST data, a collection of HII regions is also present in the plane of the galaxy, which explains the mixture of ionization mechanisms in this system. It is unlikely that the outflow in NGC 2623 will escape from the galaxy, given the low SFR intensity ($\sim$0.5 M$_{\odot}$yr$^{-1}$kpc$^{-2}$), the fact that the outflow rate is 3 times lower than the current SFR, and the escape velocity in the central areas higher than the outflow velocity.

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arXiv2017

Star formation histories in mergers: The spatially resolved properties of the early-stage merger LIRGs IC 1623 and NGC 6090

The role of major mergers in galaxy evolution is investigated through a detailed characterization of the stellar populations, ionized gas properties, and star formation rates (SFR) in the early-stage merger LIRGs IC 1623 W and NGC 6090, by analysing optical Integral Field Spectroscopy (IFS) and high resolution HST imaging. The spectra were processed with the Starlight full spectral fitting code, and the emission lines measured in the residual spectra. The results are compared with control non-interacting spiral galaxies from the CALIFA survey. Merger-induced star formation is extended and recent, as revealed by the young ages (50-80 Myr) and high contributions to light of young stellar populations (50-90$\%$), in agreement with merger simulations in the literature. These early-stage mergers have positive central gradients of the stellar metallicity, with an average $\sim$0.6 Z$_{\odot}$. Compared to non-interacting spirals, they have lower central nebular metallicity, and flatter profiles, in agreement with the gas inflow scenario. We find that they are dominated by star formation, although shock excitation cannot be discarded in some regions, where high velocity dispersion is found (170-200 km s$^{-1}$). The average SFR in these early-stage mergers ($\sim$23-32 M$_{\odot}$ yr$^{-1}$) is enhanced with respect to main-sequence Sbc galaxies by factors of 6-9, slightly above the predictions from classical merger simulations, but still possible in about 15$\%$ of major galaxy mergers, where U/LIRGs belong.

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arXiv2016

Star formation along the Hubble sequence: Radial structure of the star formation of CALIFA galaxies

The aim of this paper is to characterize the radial structure of the star formation rate (SFR) in galaxies in the nearby Universe as represented by the CALIFA survey. The sample under study contains 416 galaxies observed with IFS, covering a wide range of Hubble types and stellar masses. Spectral synthesis techniques are applied to obtain radial profiles of the intensity of the star formation rate in the recent past, and the local sSFR. To emphasize the behavior of these properties for galaxies that are on and off the main sequence of star formation (MSSF) we stack the individual radial profiles in bins of galaxy morphology and stellar masses. Our main results are: a) The intensity of SFR shows declining profiles that exhibit very little differences between spirals. The dispersion between the profiles is significantly smaller in late type spirals. This confirms that the MSSF is a sequence of galaxies with nearly constant intensity of SFR b) sSFR values scale with Hubble type and increase radially outwards, with a steeper slope in the inner 1 HLR. This behavior suggests that galaxies are quenched inside-out, and that this process is faster in the central, bulge-dominated part than in the disks. c) As a whole, and at all radii, E and S0 are off the MSSF. d) Applying the volume-corrections for the CALIFA sample, we obtain a density of star formation in the local Universe of 0.0105 Msun/yr/Mpc^{-3}. Most of the star formation is occurring in the disks of spirals. e) The volume averaged birthrate parameter, b'=0.39, suggests that the present day Universe is forming stars at 1/3 of its past average rate. E, S0, and the bulge of early type spirals contribute little to the recent SFR of the Universe, which is dominated by the disks of later spirals. f) There is a tight relation between the intensity of the SFR and stellar mass, defining a local MSSF relation with a logarithmic slope of 0.8.

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arXiv2016

Simultaneous spectroscopic and photometric analysis of galaxies with STARLIGHT: CALIFA $+$ GALEX

We present an extended version of the spectral synthesis code STARLIGHT designed to incorporate both $λ$-by-$λ$ spectra and photometric fluxes in the estimation of stellar population properties of galaxies. The code is tested with simulations and data for 260 galaxies culled from the CALIFA survey, spatially matching the 3700--7000 Å optical datacubes to GALEX near and far UV images. The sample spans E--Sd galaxies with masses from $10^9$ to $10^{12} M_\odot$ and stellar populations all the way from star-forming to old, passive systems. Comparing results derived from purely optical fits with those which also consider the NUV and FUV data we find that: (1) The new code is capable of matching the input UV data within the errors while keeping the quality of the optical fit essentially unchanged. (2) Despite being unreliable predictors of the UV fluxes, purely optical fits yield stellar population properties which agree well with those obtained in optical+UV fits for nearly 90% of our sample. (3) The addition of UV constraints has little impact on properties such as stellar mass and dust optical depth. Mean stellar ages and metallicities also remain nearly the same for most galaxies, the exception being low-mass, late-type galaxies, which become older and less enriched due to rearrangements of their youngest populations. (4) The revised ages are better correlated with observables such as the 4000 Å break index, and the $NUV - r$ and $u - r$ colours, an empirical indication that the addition of UV constraints helps mitigating the effects of age-metallicity-extinction degeneracies.

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arXiv2015

The CALIFA survey across the Hubble sequence: Spatially resolved stellar population properties in galaxies

This paper characterizes the radial structure of stellar population properties of galaxies in the nearby universe, based on 300 galaxies from the CALIFA survey. The sample covers a wide range of Hubble types, and galaxy stellar mass. We apply the spectral synthesis techniques to recover the stellar mass surface density, stellar extinction, light and mass-weighted ages, and mass-weighted metallicity, for each spatial resolution element in our target galaxies. To study mean trends with overall galaxy properties, the individual radial profiles are stacked in seven bins of galaxy morphology. We confirm that more massive galaxies are more compact, older, more metal rich, and less reddened by dust. Additionally, we find that these trends are preserved spatially with the radial distance to the nucleus. Deviations from these relations appear correlated with Hubble type: earlier types are more compact, older, and more metal rich for a given mass, which evidences that quenching is related to morphology, but not driven by mass. Negative gradients of ages are consistent with an inside-out growth of galaxies, with the largest ages gradients in Sb-Sbc galaxies. Further, the mean stellar ages of disks and bulges are correlated, with disks covering a wider range of ages, and late type spirals hosting younger disks. The gradients in stellar mass surface density depend mostly on stellar mass, in the sense that more massive galaxies are more centrally concentrated. There is a secondary correlation in the sense that at the same mass early type galaxies have steeper gradients. We find mildly negative metallicity gradients, shallower than predicted from models of galaxy evolution in isolation. The largest gradients occur in Sb galaxies. Overall we conclude that quenching processes act in manners that are independent of mass, while metallicity and galaxy structure are influenced by mass-dependent processes.

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arXiv2015

The CALIFA survey across the Hubble sequence: How galaxies grow their bulges and disks

We characterize in detail the radial structure of the stellar population properties of 300 galaxies in the nearby universe, observed with integral field spectroscopy in the CALIFA survey. The sample covers a wide range of Hubble types, from spheroidal to spiral galaxies, ranging in stellar masses from $M_\star \sim 10^9$ to $7 \times 10^{11}$ $M_\odot$. We derive the stellar mass surface density ($μ_\star$), light-weighted and mass-weighted ages ($\langle {\rm log}\,age\rangle _L$, $\langle {\rm log}\,age\rangle _M$), and mass-weighted metallicity ($\langle {\rm log}\,Z_\star\rangle _M$), applying the spectral synthesis technique. We study the mean trends with galaxy stellar mass, $M_\star$, and morphology (E, S0, Sa, Sb, Sbc, Sc and Sd). We confirm that more massive galaxies are more compact, older, more metal rich, and less reddened by dust. Additionally, we find that these trends are preserved spatially with the radial distance to the nucleus. Deviations from these relations appear correlated with Hubble type: earlier types are more compact, older, and more metal rich for a given M$_\star$, which evidences that quenching is related to morphology, but not driven by mass.

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