Surface Mass Density Research Articles

Fast and Sensitive Ellipsometry-Based Biosensing.

In this work, a biosensing method based on in situ, fast, and sensitive measurements of ellipsometric parameters (Ψ, ∆) is proposed. Bare silicon wafer substrate is functionalized and used to bind biomolecules in the solution. Coupled with a 45° dual-drive symmetric photoelastic modulator-based ellipsometry, the parameters Ψ and ∆ of biolayer arising due to biomolecular interactions are determined directly, and the refractive index (RI) of the solution and the effective thickness and surface mass density of the biolayer for various interaction time can be further monitored simultaneously. To illustrate the performance of the biosensing method, immunosensing for immunoglobulin G (IgG) was taken as a case study. The experiment results show that the biosensor response of the limit of detection for IgG is 15 ng/mL, and the data collection time is in milliseconds. Moreover, the method demonstrates a good specificity. Such technique is a promising candidate in developing a novel sensor which can realize fast and sensitive, label-free, easy operation, and cost-effective biosensing.

First Results on the Cluster Galaxy Population from the Subaru Hyper Suprime-Cam Survey. III. Brightest Cluster Galaxies, Stellar Mass Distribution, and Active Galaxies

Abstract The unprecedented depth and area surveyed by the Subaru Strategic Program with the Hyper Suprime-Cam (HSC-SSP) have enabled us to construct and publish the largest distant cluster sample out to to date. In this exploratory study of cluster galaxy evolution from z = 1 to z = 0.3, we investigate the stellar mass assembly history of brightest cluster galaxies (BCGs), the evolution of stellar mass and luminosity distributions, the stellar mass surface density profile, as well as the population of radio galaxies. Our analysis is the first high-redshift application of the top N richest cluster selection, which is shown to allow us to trace the cluster galaxy evolution faithfully. Over the 230 deg2 area of the current HSC-SSP footprint, selecting the top 100 clusters in each of the four redshift bins allows us to observe the buildup of galaxy population in descendants of clusters whose mass is about . Our stellar mass is derived from a machine-learning algorithm, which is found to be unbiased and accurate with respect to the COSMOS data. We find very mild stellar mass growth in BCGs (about 35% between z = 1 and 0.3), and no evidence for evolution in both the total stellar mass–cluster mass correlation and the shape of the stellar mass surface density profile. We also present the first measurement of the radio luminosity distribution in clusters out to , and show hints of changes in the dominant accretion mode powering the cluster radio galaxies at .

Individual stellar haloes of massive galaxies measured to 100 kpc at 0.3 < z < 0.5 using Hyper Suprime-Cam

Massive galaxies display extended light profiles that can reach several hundreds of kilo parsecs. These stellar halos provide a fossil record of galaxy assembly histories. Using data that is both wide (~100 square degree) and deep (i>28.5 mag/arcsec^2 in i-band), we present a systematic study of the stellar halos of a sample of more than 3000 galaxies at 0.3 < z < 0.5 with $\log M_{\star}/M_{\odot} > 11.4$. Our study is based on high-quality (0.6 arcsec seeing) imaging data from the Hyper Suprime-Cam (HSC) Subaru Strategic Program (SSP), which enables us to individually estimate surface mass density profiles to 100 kpc without stacking. As in previous work, we find that more massive galaxies exhibit more extended outer profiles. When this extended light is not properly accounted for as a result of shallow imaging or inadequate profile modeling, the derived stellar mass function can be significantly underestimated at the highest masses. Across our sample, the ellipticity of outer light profiles increases substantially as we probe larger radii. We show for the first time that these ellipticity gradients steepen dramatically as a function of galaxy mass, but we detect no mass-dependence in outer color gradients. Our results support the two-phase formation scenario for massive galaxies in which outer envelopes are built up at late times from a series of merging events. We provide surface mass surface mass density profiles in a convenient tabulated format to facilitate comparisons with predictions from numerical simulations of galaxy formation.

Mass Profile Decomposition of the Frontier Fields Cluster MACS J0416-2403: Insights on the Dark-matter Inner Profile

Abstract We present a high-resolution dissection of the two-dimensional total mass distribution in the core of the Hubble Frontier Fields galaxy cluster MACS J0416.1−2403, at z = 0.396. We exploit HST/WFC3 near-IR (F160W) imaging, VLT/Multi Unit Spectroscopic Explorer spectroscopy, and Chandra data to separate the stellar, hot gas, and dark-matter mass components in the inner 300 kpc of the cluster. We combine the recent results of our refined strong lensing analysis, which includes the contribution of the intracluster gas, with the modeling of the surface brightness and stellar mass distributions of 193 cluster members, of which 144 are spectroscopically confirmed. We find that, moving from 10 to 300 kpc from the cluster center, the stellar to total mass fraction decreases from 12% to 1% and the hot gas to total mass fraction increases from 3% to 9%, resulting in a baryon fraction of approximatively 10% at the outermost radius. We measure that the stellar component represents ∼30%, near the cluster center, and 15%, at larger clustercentric distances, of the total mass in the cluster substructures. We subtract the baryonic mass component from the total mass distribution and conclude that within 30 kpc (∼3 times the effective radius of the brightest cluster galaxy) from the cluster center the surface mass density profile of the total mass and global (cluster plus substructures) dark-matter are steeper and that of the diffuse (cluster) dark-matter is shallower than an NFW profile. Our current analysis does not point to a significant offset between the cluster stellar and dark-matter components. This detailed and robust reconstruction of the inner dark-matter distribution in a larger sample of galaxy clusters will set a new benchmark for different structure formation scenarios.

Extended Schmidt law holds for faint dwarf irregular galaxies

The extended Schmidt law (ESL) is a variant of the Schmidt law which relates the surface densities of gas and star formation, with the surface density of stellar mass added as an extra parameter. We empirically investigate for the first time whether low metallicity faint dwarf irregular galaxies (dIrrs) follow the ESL. Here we consider the `global' law where surface densities are averaged over the galactic discs. dIrrs are unique not only because they are at the lowest end of mass and star formation scales for galaxies, but also because they are metal-poor compared to the general population of galaxies. Our sample is drawn from the Faint Irregular Galaxy GMRT Survey (FIGGS) which is the largest survey of atomic hydrogen in such galaxies. The gas surface densities are determined using their atomic hydrogen content. The star formation rates are calculated using GALEX far ultraviolet fluxes after correcting for dust extinction, whereas the stellar surface densities are calculated using Spitzer 3.6 $\mu$m fluxes. All surface densities are calculated over stellar discs defined by the 3.6 $\mu$m images. We find dIrrs indeed follow the extended Schmidt law. The mean deviation of the FIGGS galaxies from the relation is 0.01 dex, with a scatter around the relation of less than half that seen in the original relation. In comparison, we also show that the FIGGS galaxies are much more deviant when compared to the `canonical' Kennicutt-Schmidt relation. Our results help strengthen the universality of the extended Schmidt law, especially for galaxies with low metallicities. We suggest that models of star formation in which feedback from previous generations of stars set the pressure in the ISM, are promising candidates for explaining the ESL. We also confirm that ESL is an independent relation and not a form of a relation between star formation efficiency and metallicity.

The spatially resolved star formation history of CALIFA galaxies

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 ($\Sigma_{\star}$). 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, $\Sigma_{\star}$, 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$_{\star}$, $\Sigma_{\star}$, 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 $\Sigma_{\star}$ 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 $\Sigma_{\star}$. There is no significant dependence on M$_{\star}$ within a particular $\Sigma_{\star}$ bin, except for the lowest bin, where the gradients becomes steeper.

On the Dark Matter Column Density in Haloes

We study the correlation between the central surface density and the halo core radius of the dark matter haloes of galaxies and clusters of galaxies. We find that the surface density within the halo characteristic radius r* is not an universal quantity as claimed by some authors (e.g., [1]), but it correlates with several physical quantities (e.g., the halo mass M200 and the magnitude M B ). The slope of the surface density—mass relation is 0.18 ± 0.05, leaving small room to the possibility of a constant surface density. Finally, we compare the results with the MOND prediction.

Gemini NIFS survey of feeding and feedback processes in nearby active galaxies – II. The sample and surface mass density profiles

We present and characterize a sample of 20 nearby Seyfert galaxies selected for having BAT 14--195keV luminosities $L_X \ge 10^{41.5}$ erg s$^{-1}$, redshift $z\le$0.015, being accessible for observations with the Gemini Near-Infrared Field Spectrograph (NIFS) and showing extended [OIII]$\lambda$5007 emission. Our goal is to study Active Galactic Nuclei (AGN) feeding and feedback processes from near-infrared integral-field spectra, that include both ionized (HII) and hot molecular (H$_2$) emission. This sample is complemented by other 9 Seyfert galaxies previously observed with NIFS. We show that the host galaxy properties (absolute magnitudes $M_B$, $M_H$, central stellar velocity dispersion and axial ratio) show a similar distribution to those of the 69 BAT AGN. For the 20 galaxies already observed, we present surface mass density ($\Sigma$) profiles for HII and H$_2$ in their inner $\sim$500 pc, showing that HII emission presents a steeper radial gradient than H$_2$. This can be attributed to the different excitation mechanisms: ionization by AGN radiation for HII and heating by X-rays for H$_2$. The mean surface mass densities are in the range ($0.2\le \Sigma_{HII} \le 35.9$)M$_\odot$pc$^{-2}$, and ($0.2\le \Sigma_{H2} \le 13.9$)$\times10^{-3}$M$_\odot$pc$^{-2}$, while the ratios between the HII and H$_2$ masses range between $\sim$200 to 8000. The sample presented here will be used in future papers to map AGN gas excitation and kinematics, providing a census of the mass inflow and outflow rates and power as well as their relation with the AGN luminosity.

First Characterization of the Neutral ISM in Two Local Volume Dwarf Galaxies

Abstract We present the first H i spectral-line images of the nearby, star-forming dwarf galaxies UGC 11411 and UGC 8245, acquired as part of the “Observing for University Classes” program with the Karl G. Jansky Very Large Array (VLA). These low-resolution images localize the H i gas and reveal the bulk kinematics of each system. Comparing with Hubble Space Telescope (HST) broadband and ground-based Hα imaging, we find that the ongoing star formation in each galaxy is associated with the highest H i mass surface density regions. UGC 8245 has a much lower current star formation rate than UGC 11411, which harbors very high surface brightness Hα emission in the inner disk and diffuse, lower surface brightness nebular gas that extends well beyond the stellar disk as traced by HST. We measure the dynamical masses of each galaxy and find that the halo of UGC 11411 is more than an order of magnitude more massive than the halo of UGC 8245, even though the H i and stellar masses of the sources are similar. We show that UGC 8245 shares similar physical properties with other well-studied low-mass galaxies, while UGC 11411 is more highly dark matter dominated. Both systems have negative peculiar velocities that are associated with a coherent flow of nearby galaxies at high supergalactic latitude.

Early science with the Large Millimetre Telescope: fragmentation of molecular clumps in the Galaxy

Sensitive, imaging observations of the 1.1 mm dust continuum emission from a 1 deg^2 area collected with the AzTEC bolometer camera on the Large Millimeter Telescope are presented. A catalog of 1545 compact sources is constructed based on a Wiener-optimization filter. These sources are linked to larger clump structures identified in the Bolocam Galactic Plane Survey. Hydrogen column densities are calculated for all sources and mass and mean volume densities are derived for the subset of sources for which kinematic distances can be assigned. The AzTEC sources are localized, high density peaks within the massive clumps of molecular clouds and comprise 5-15% of the clump mass. We examine the role of the gravitational instability in generating these fragments by comparing the mass of embedded AzTEC sources to the Jeans' mass of the parent BGPS object. For sources with distances less than 6 kpc the fragment masses are comparable to the clump Jeans' mass, despite having isothermal Mach numbers between 1.6 and 7.2. AzTEC sources linked to ultra-compact HII regions have mass surface densities greater than the critical value implied by the mass-size relationship of infrared dark clouds with high mass star formation while AzTEC sources associated with Class II methanol masers have mass surface densities greater than 0.7 g cm^{-2} that approaches the proposed threshold required to form massive stars.

Most pseudo-bulges can be formed at later stages of major mergers

Most giant spiral galaxies have pseudo or disk-like bulges that are considered to be the result of purely secular processes. This may challenge the hierarchical scenario predicting about one major merger per massive galaxy ($>$$3\times 10^{10} M_{\odot}$) since the last $\sim$ 9 billion years. Here we verify whether or not the association between pseudo-bulges and secular processes is irrevocable. Using GADGET2 N-body/SPH simulations, we have conducted a systematic study of remnants of major mergers which progenitors have been selected (1) to follow the gas richness-look back time relationship, and (2) with a representative distribution of orbits and spins in a cosmological frame. Analyzing the surface-mass density profile of both nearby galaxies and merger remnants with two components, we find that most of them show pseudo-bulges or bar dominated centers. Even if some orbits lead to classical bulges just after the fusion, the contamination by the additional gas that gradually accumulates to the center and forming stars later on, leads to remnants apparently dominated by pseudo-bulges. We also found that simple SPH simulations should be sufficient to form realistic spiral galaxies as remnants of ancient gas-rich mergers without need for specifically tuned feedback conditions. We then conclude that pseudo-bulges and bars in spiral galaxies are natural consequences of major mergers when they are realized in a cosmological context, i.e., with gas-rich progenitors as expected when selected in the distant Universe.

The SAMI Galaxy Survey: understanding observations of large-scale outflows at low redshift with EAGLE simulations

AbstractThis work presents a study of galactic outflows driven by stellar feedback. We extract main-sequence disc galaxies with stellar mass 109 ≤ M⋆/ M⊙ ≤ 5.7 × 1010 at redshift z = 0 from the highest resolution cosmological simulation of the Evolution and Assembly of GaLaxies and their Environments (EAGLE) set. Synthetic gas rotation velocity and velocity dispersion (σ) maps are created and compared to observations of disc galaxies obtained with the Sydney-AAO (Australian Astronomical Observatory) Multi-object Integral field spectrograph (SAMI), where σ-values greater than 150 km s−1 are most naturally explained by bipolar outflows powered by starburst activity. We find that the extension of the simulated edge-on (pixelated) velocity dispersion probability distribution depends on stellar mass and star formation rate surface density (ΣSFR), with low-M⋆/low-ΣSFR galaxies showing a narrow peak at low σ (∼30 km s−1) and more active, high-M⋆/high-ΣSFR galaxies reaching σ &amp;gt; 150 km s−1. Although supernova-driven galactic winds in the EAGLE simulations may not entrain enough gas with T &amp;lt;105 K compared to observed galaxies, we find that gas temperature is a good proxy for the presence of outflows. There is a direct correlation between the thermal state of the gas and its state of motion as described by the σ-distribution. The following equivalence relations hold in EAGLE: (i) low-σ peak ⇔ disc of the galaxy ⇔ gas with T &amp;lt;105 K; (ii) high-σ tail ⇔ galactic winds ⇔ gas with T ≥105 K.

Radial distribution of dust, stars, gas, and star-formation rate in DustPedia face-on galaxies

The purpose of this work is the characterization of the radial distribution of dust, stars, gas, and star-formation rate (SFR) in a sub-sample of 18 face-on spiral galaxies extracted from the DustPedia sample. This study is performed by exploiting the multi-wavelength, from UV to sub-mm bands, DustPedia database, in addition to molecular (12CO) and atomic (HI) gas maps and metallicity abundance information available in the literature. We fitted the surface brightness profiles of the tracers of dust and stars, the mass surface density profiles of dust, stars, molecular gas, and total gas, and the SFR surface density profiles with an exponential curve and derived their scale-lengths. We also developed a method to solve for the CO-to-H2 conversion factor (alpha_CO) per galaxy by using dust and gas mass profiles. Although each galaxy has its own peculiar behaviour, we identified a common trend of the exponential scale-lengths vs. wavelength. On average, the scale-lengths normalized to the B-band 25 mag/arcsec^2 radius decrease from UV to 70 micron, from 0.4 to 0.2, and then increase back up to 0.3 at 500 microns. The main result is that, on average, the dust mass surface density scale-length is about 1.8 times the stellar one derived from IRAC data and the 3.6 micron surface brightness, and close to that in the UV. We found a mild dependence of the scale-lengths on the Hubble stage T: the scale-lengths of the Herschel bands and the 3.6 micron scale-length tend to increase from earlier to later types, the scale-length at 70 micron tends to be smaller than that at longer sub-mm wavelength with ratios between longer sub-mm wavelengths and 70 micron that decrease with increasing T. The scale-length ratio of SFR and stars shows a weak increasing trend towards later types.

The SAMI Galaxy Survey: global stellar populations on the size–mass plane

We present an analysis of the global stellar populations of galaxies in the SAMI Galaxy Survey. Our sample consists of 1319 galaxies spanning four orders of magnitude in stellar mass and includes all morphologies and environments. We derive luminosity-weighted, single stellar population equivalent stellar ages, metallicities and alpha enhancements from spectra integrated within one effective radius apertures. Variations in galaxy size explain the majority of the scatter in the age--mass and metallicity--mass relations. Stellar populations vary systematically in the plane of galaxy size and stellar mass, such that galaxies with high stellar surface mass density are older, more metal-rich and alpha-enhanced than less dense galaxies. Galaxies with high surface mass densities have a very narrow range of metallicities, however, at fixed mass, the spread in metallicity increases substantially with increasing galaxy size (decreasing density). We identify residual correlations with morphology and environment. At fixed mass and size, galaxies with late-type morphologies, small bulges and low Sersic n are younger than early-type, high n, high bulge-to-total galaxies. Age and metallicity both show small residual correlations with environment; at fixed mass and size, galaxies in denser environments or more massive halos are older and somewhat more metal rich than those in less dense environments. We connect these trends to evolutionary tracks within the size--mass plane.

The Local Volume H i Survey: star formation properties

We built a multi-wavelength dataset for galaxies from the Local Volume HI Survey (LVHIS), which comprises 82 galaxies. We also select a sub-sample of ten large galaxies for investigating properties in the galactic outskirts. The LVHIS sample covers nearly four orders of magnitude in stellar mass and two orders of magnitude in HI mass fraction (fHI). The radial distribution of HI gas with respect to the stellar disc is correlated with fHI but with a large scatter. We confirm the previously found correlations between the total HI mass and star formation rate (SFR), and between HI surface densities and SFR surface densities beyond R25. However, the former correlation becomes much weaker when the average surface densities rather than total mass or rate are considered, and the latter correlation also becomes much weaker when the effect of stellar mass is removed or controlled. Hence the link between SFR and HI is intrinsically weak in these regions, consistent with what was found on kpc scales in the galactic inner regions. We find a strong correlation between the SFR surface density and the stellar mass surface density, which is consistent with the star formation models where the gas is in quasi-equilibrium with the mid-plane pressure. We find no evidence for HI warps to be linked with decreasing star forming efficiencies.

Mass discrepancy–acceleration relation in Einstein rings

We study the Mass Discrepancy-Acceleration Relation (MDAR) of 57 elliptical galaxies by their Einstein rings from the Sloan Lens ACS Survey (SLACS). The mass discrepancy between the lensing mass and the baryonic mass derived from population synthesis is larger when the acceleration of the elliptical galaxy lenses is smaller. The MDAR is also related to surface mass density discrepancy. At the Einstein ring, these lenses belong to high-surface-mass density galaxies. Similarly, we find that the discrepancy between the lensing and stellar surface mass density is small. It is consistent with the recent discovery of dynamical surface mass density discrepancy in disk galaxies where the discrepancy is smaller when surface density is larger. We also find relativistic modified Newtonian dynamics (MOND) can naturally explain the MDAR and surface mass density discrepancy in 57 Einstein rings. Moreover, the lensing mass, the dynamical mass and the stellar mass of these galaxies are consistent with each other in relativistic MOND.

Dynamic collapses of relativistic degenerate stellar cores and radiation pressure dominated stellar interiors

We investigate and explore self-similar dynamic radial collapses of relativistic degenerate stellar cores (RDSCs) and radiation pressure dominated stellar interiors (RPDSIs) of spherical symmetry by invoking a conventional polytropic (CP) equation of state (EoS) with a constant polytropic index γ=4/3 and by allowing free-fall non-zero RDSC or RPDSI surface mass density and pressure due to their sustained physical contact with the outer surrounding stellar envelopes also in contraction. Irrespective of the physical triggering mechanisms (including, e.g., photodissociation, electron-positron pair instability, general relativistic instability etc.) for initiating such a self-similar dynamically collapsing RDSC or RPDSI embedded within a massive star, a very massive star (VMS) or a supermassive star (SMS) in contraction and by comparing with the Schwarzschild radii associated with their corresponding RDSC/RPDSI masses, the emergence of central black holes in a wide mass range appears inevitable during such RDSC/RPDSI dynamic collapses inside massive stars, VMSs, and SMSs, respectively. Radial pulsations of progenitor cores or during a stellar core collapse may well leave imprints onto collapsing RDSCs/RPDSIs towards their self-similar dynamic evolution. Massive neutron stars may form during dynamic collapses of RDSC inside massive stars in contraction under proper conditions.

The Properties of the Massive Star-forming Galaxies with an Outside-in Assembly Mode

Abstract Previous findings show that massive ( ) star-forming (SF) galaxies usually have an “inside-out” stellar mass assembly mode. In this paper, we have for the first time selected a sample of 77 massive SF galaxies with an “outside-in” assembly mode (called the “targeted sample”) from the Mapping Nearby Galaxies at the Apache Point Observatory (MaNGA) survey. For comparison, two control samples are constructed from the MaNGA sample matched in stellar mass: a sample of 154 normal SF galaxies and a sample of 62 quiescent galaxies. In contrast to normal SF galaxies, the targeted galaxies appear to be smoother and more bulge-dominated and have a smaller size and higher concentration, star formation rate, and gas-phase metallicity as a whole. However, they have a larger size and lower concentration than quiescent galaxies. Unlike the normal SF sample, the targeted sample exhibits a slightly positive gradient of the 4000 Å break and a pronounced negative gradient of Hα equivalent width. Furthermore, the median surface mass density profile is between those of the normal SF and quiescent samples, indicating that the gas accretion of quiescent galaxies is not likely to be the main approach for the outside-in assembly mode. Our results suggest that the targeted galaxies are likely in the transitional phase from normal SF galaxies to quiescent galaxies, with rapid ongoing central stellar mass assembly (or bulge growth). We discuss several possible formation mechanisms for the outside-in mass assembly mode.

Dust Emission at 8 and 24 μm as Diagnostics of H ii Region Radiative Transfer

Abstract We use the Spitzer Surveying the Agents of Galaxy Evolution (SAGE) survey of the Magellanic Clouds to evaluate the relationship between the 8 μm polycyclic aromatic hydrocarbon (PAH) emission, 24 μm hot dust emission, and H ii region radiative transfer. We confirm that in the higher-metallicity Large Magellanic Cloud, PAH destruction is sensitive to optically thin conditions in the nebular Lyman continuum: objects identified as optically thin candidates based on nebular ionization structure show six times lower median 8 μm surface brightness (0.18 mJy arcsec−2) than their optically thick counterparts (1.2 mJy arcsec−2). The 24 μm surface brightness also shows a factor of three offset between the two classes of objects (0.13 versus 0.44 mJy arcsec−2, respectively), which is driven by the association between the very small dust grains and higher density gas found at higher nebular optical depths. In contrast, PAH and dust formation in the low-metallicity Small Magellanic Cloud is strongly inhibited such that we find no variation in either 8 μm or 24 μm emission between our optically thick and thin samples. This is attributable to extremely low PAH and dust production together with high, corrosive UV photon fluxes in this low-metallicity environment. The dust mass surface densities and gas-to-dust ratios determined from dust maps using Herschel HERITAGE survey data support this interpretation.

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 $\mathrm{H}\alpha$ 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.