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Item Diagnostic diagrams for ram pressure stripped candidates(Royal Astronomical Society) Krabbe, Angela Cristina; Hernandez-Jimenez, José Andrés; Oliveira, Claudia Mendes de; Jaffe, Yara L.; Oliveira Junior, Celso Benedito de; Cardoso, Nathalia Machado; Castelli, Analía V Smith; Dors Junior, Oli Luiz; Cortesi, Arianna; Crossett, Jacob P.This paper presents a method for finding ram pressure stripped (RPS) galaxy candidates by performing a morphological analysis of galaxy images obtained from the Legacy survey. We consider a sample of about 600 galaxies located in different environments such as groups and clusters, tidally interacting pairs and the field. The sample includes 160 RPS previously classified in the literature into classes from J1 to J5, based on the increasing level of disturbances. Our morphological analysis was done using the ASTROMORPHLIB software followed by the inspection of diagnostic diagrams involving combinations of different parameters like the asymmetry (A), concentration (C), Sersic ´ index (n), and bulge strength parameters F(G, M20). We found that some of those diagrams display a distinct region in which galaxies classified as J3, J4, and J5 decouples from isolated galaxies. We call this region as the morphological transition zone and we also found that tidally interacting galaxies in pairs are predominant within this zone. Nevertheless, after visually inspecting the objects in the morphological transition zone to discard obvious contaminants, we ended up with 33 bona fide new RPS candidates in the studied nearby groups and clusters (Hydra, Fornax, and CLoGS sample), of which one-third show clear evidence of unwinding arms. Future works may potentially further increase significantly the samples of known RPS using such method.Item Chemical abundances in Seyfert galaxies – IX. Helium abundance estimates(Royal Astronomical Society) Dors Junior, Oli Luiz; Valerdi, Mabel; Lemes, Priscila Freitas; Krabbe, Angela Cristina; Riffel, Rogemar André; Amôres, Eduardo Brescansin; Riffel, Rogério; Armah, Mark; Monteiro, Adriano Francisco; Oliveira Junior, Celso Benedito deFor the first time, the helium abundance relative to hydrogen (He/H), which relied on direct measurements of the electron temperature, has been derived in the narrow line regions (NLRs) from a local sample of Seyfert 2 nuclei. In view of this, optical emission line intensities [3000 < λ(Å) < 7000] of 65 local Seyfert 2 nuclei (z < 0.2), taken from Sloan Digital Sky Survey Data Release 15 and additional compilation from the literature, were considered. We used photoionization model grid to derive an Ionization Correction Factor (ICF) for the neutral helium. The application of this ICF indicates that the NLRs of Seyfert 2 present a neutral helium fraction of ∼50 per cent in relation to the total helium abundance. We find that Seyfert 2 nuclei present helium abundance ranging from 0.60 to 2.50 times the solar value, while ∼85 per cent of the sample present oversolar abundance values. The derived (He/H)–(O/H) abundance relation from the Seyfert 2 is stepper than that of star-forming regions (SFs) and this difference could be due to excess of helium injected into the interstellar medium by the winds of Wolf–Rayet stars. From a regression to zero metallicity, by using Seyfert 2 estimates combined with SFs estimates, we obtained a primordial helium mass fraction Yp = 0.2441 ± 0.0037, a value in good agreement with the one inferred from the temperature fluctuations of the cosmic microwave background by the Planck CollaborationItem Calibration-based abundances in the interstellar gas of galaxies from slit and IFU spectra(EDP Sciences) Pilyugin, Leonid; Lara-López, Maritza A.; Vílchez, Jose M.; Duarte Puertas, Salvador; Zinchenko, Igor; Dors Junior, Oli LuizIn this work, we make use of available integral field unit (IFU) spectroscopy and slit spectra of several nearby galaxies. The pre- existing empirical R and S calibrations for abundance determinations are constructed using a sample of H ii regions with high- quality slit spectra. In this paper, we test the applicability of those calibrations to the IFU spectra. We estimate the calibration-based abundances obtained using both the IFU and the slit spectroscopy for eight nearby galaxies. The median values of the slit and IFU spectra-based abundances in bins of 0.1 in fractional radius Rg (normalised to the optical radius R25) of a galaxy are determined and compared. We find that the IFU and the slit spectra-based abundances obtained through the R calibration are close to each other; the mean value of the differences of abundances is 0.005 dex, and the scatter in the differences is 0.037 dex for 38 datapoints. The S calibration can produce systematically underestimated values of the IFU spectra-based abundances at high metallicities (12 + log(O/H) 8.55); the mean value of the differences is −0.059 dex for 21 datapoints, while at lower metallicities the mean value of the differences is −0.018 dex and the scatter is 0.045 dex for 36 data points. This provides evidence that the R calibration produces more consistent abundance estimations between the slit and the IFU spectra than the S calibration. We find that the same calibration can produce close estimations of the abundances using IFU spectra obtained with different spatial resolution and different spatial samplings. This is in line with the recent finding that the contribution of the diffuse ionised gas to the large-aperture spectra of H ii regions has a secondary effect.Item Gas-phase metallicity determinations in nearby AGNs with SDSS-IV MaNGA: evidence of metal-poor accretion(Royal Astronomical Society) Nascimento, Janaína Correa do; Dors Junior, Oli Luiz; Bergmann, Thaisa Storchi; Mallmann, Nícolas Dullius; Riffel, Rogério; Ilha, Gabriele da Silva; Riffel, Rogemar André; Rembold, Sandro Barboza; Deconto-Machado, Alice; Costa, Luiz N. da; Armah, MarkWe derive the metallicity (traced by the O/H abundance) of the narrow-line region (NLR) of 108 Seyfert galaxies as well as radial metallicity gradients along their galaxy discs and of these of a matched control sample of no active galaxies. In view of that, observational data from the SDSS-IV MaNGA survey and strong emission-line calibrations taken from the literature were considered. The metallicity obtained for the NLRs was compared to the value derived from the extrapolation of the radial oxygen abundance gradient, obtained from H II region estimates along the galaxy disc, to the central part of the host galaxies. We find that, for most of the objects (∼ 80 per cent), the NLR metallicity is lower than the extrapolated value, with the average difference (D ) between these estimates ranging from 0.16 to 0.30 dex. We suggest that D is due to the accretion of metal-poor gas to the AGN that feeds the nuclear supermassive black hole (SMBH), which is drawn from a reservoir molecular and/or neutral hydrogen around the SMBH. Additionally, we look for correlations between D and the electron density (Ne), [O III]λ5007, and H α luminosities, extinction coefficient (AV) of the NLRs, as well as the stellar mass (M∗) of the host galaxies. Evidence of an inverse correlation between the D and the parameters Ne, M∗, and Av was found.Item Chemical abundances in Seyfert galaxies – X. Sulphur abundance estimates(Royal Astronomical Society) Dors Junior, Oli Luiz; Valerdi, Mabel; Riffel, Rogemar André; Riffel, Rogério; Cardaci, Mónica Viviana; Hägele, Guilhermo Frederico; Armah, Mark; Revalski, Mitchell; Flury, Sophia; Lemes, Priscila Freitas; Amôres, Eduardo; Krabbe, Angela Cristina; Binette, Luc; Feltre, Anna; Bergmann, Thaisa StorchiFor the first time, the sulphur abundance relative to hydrogen (S/H) in the narrow-line regions of a sample of Seyfert 2 nuclei (Sy 2s) has been derived via direct estimation of the electron temperature. Narrow emission-line intensities from the Sloan Digital Sky Survey (SDSS) Data Release 17 (DR17) [in the wavelength range 3000 < λ(Å) < 9100] and from the literature for a sample of 45 nearby (z < 0.08) Sy 2s were considered. Our direct estimates indicate that Sy 2s have similar temperatures in the gas region where most of the S+ ions are located in comparison with that of star-forming regions (SFs). However, Sy 2s present higher temperature values (∼10 000 K) in the region where most of the S2+ ions are located relative to that of SFs. We derive the total sulphur abundance in the range of 6.2 12 + log(S/H) 7.5, corresponding to 0.1–1.8 times the solar value. These sulphur abundance values are lower by ∼0.4 dex than those derived in SFs with similar metallicity, indicating a distinct chemical enrichment of the interstellar medium (ISM) for these object classes. The sulphur abundance relative to oxygen (S/O) values for our Sy 2 sample present an abrupt (∼0.5 dex) decrease with increasing oxygen abundance relative to hydrogen (O/H) for the high-metallicity regime [12 + log(O/H) 8.7)], what is not seen for the SFs. However, when our Sy 2 estimates are combined with those from a large sample of SFs, we did not find any dependence between S/O and O/H.Item Chemical abundances of LINER galaxies – nitrogen abundance estimations(Royal Astronomical Society) Oliveira Junior, Celso Benedito de ; Krabbe, Angela Cristina; Dors Junior, Oli Luiz; Zinchenko, Igor; Hernandez-Jimenez, José Andrés; Cardaci, Mónica Viviana; Hägele, Guilhermo Frederico; Ilha, Gabriele da SilvaIn this work, we investigated the nitrogen and oxygen abundances in a sample of galaxies with Low Ionization Nuclear Emission Regions (LINERs) in their nucleus. Optical spectroscopic data (3600 – 10 000 Å) of 40 LINERs from the Mapping Nearby Galaxies (MaNGAs) survey were considered. Only objects classified as retired galaxies, that is, whose main ionization sources are post-Asymptotic Giant Branch (pAGB) stars, were selected. The abundance estimates were obtained through detailed photoionization models built with the CLOUDY code to reproduce a set of observational emission line intensities ratios of the sample. Our results show that LINERs have oxygen and nitrogen abundances in the ranges of 8.0 12 + log(O/H) 9.0 (mean value 8.74 ± 0.27) and 7.6 12 + log(N/H) 8.5 (mean value 8.05 ± 0.25), respectively. About 70 per cent of the sample have oversolar O/H and N/H abundances. Our abundance estimates are in consonance with those for Seyfert 2 nuclei and H II regions with the highest metallicity, indicating that these distinct object classes show similar enrichment of the interstellar medium (ISM). The LINERs in our sample are located in the higher N/O region of the N/O versus O/H diagram, showing an unexpected negative correlation between these two parameters. These results suggest that these LINERs mainly exhibit a secondary nitrogen production and could be acting some other mechanisms that deviate them from the usual theoretical secondary nitrogen production curve and the H II regions observations. However, we did not find any evidence in our data able to support the literature suggested mechanisms. Alternatively, our results show that LINERs do not present any correlation between the N/O abundances and the stellar masses of the hosting galaxies.Item Constraints on the densities and temperature of the Seyfert 2 narrow line region(EDP Sciences) Binette, Luc; Martin, Montserrat Villar; Dors Junior, Oli Luiz; Krongold, Yair; Morisset, Christophe; Revalski, Mitchell; Alarie, Alexandre; Riffel, Rogemar André; Dopita, MichaelContext. Different studies have reported the so-called temperature problem of the narrow line region (NLR) of active galactic nuclei (AGNs). Its origin is still an open issue. To properly address its cause, a trustworthy temperature indicator is required. Aims. To determine the temperature of an emission line plasma, the [O iii] (λ4363Å/λ5007Å) line ratio is typically used. However, in the case of the NLR of AGNs, this ratio is not reliable when the electron density extends much above 10 cm−3 as collisional deexcitation strongly affects this ratio independently of the temperature. To verify the density regime, we need a density diagnostic that applies to high excitation plasma. Methods. We propose that the weak [Ar iv] λλ4711,40Å doublet is the appropriate tool for evaluating the density of the high excitation plasma. We subsequently made use of the recent S7 survey sample to extract reliable measurements of the weak [Ar iv] doublet in 16 high excitation Seyfert 2s. As a result we could derive the plasma density of the NLR of our Seyfert 2 sample and compared the temperature inferred from the observed [O iii] (λ4363Å/λ5007Å) ratios. Results. It was found that 13 Seyfert 2s cluster near similar values as the [O iii] (λ4363Å/λ5007Å) ratio, at a mean value of 0.0146 ± 0.0020. Three objects labeled outliers stand out at markedly higher [O iii] values (>0.03). Conclusions. If for each object one assumes a single density, the values inferred from the [Ar iv] doublet for the 13 clustering objects all lie below 60 000 cm−3 , indicating that the [O iii] (λ4363Å/λ5007Å) ratios in these objects is a valid tracer of plasma temperature. Even when assuming a continuous power-law distribution of the density, the inferred cut-off density required to reproduce the observed 5.1 −3 [Ar iv] doublet is in all cases <10 cm. The average NLR temperature inferred for the 13 Seyfert 2s is 13 000 ± 703 K, which photoionization models have difficulty reproducing. Subsequently we considered different mechanisms to account for the observed [O iii] ratios. For the three outliers, a double-bump density distribution is likely required, with the densest component having a density >10 cm-3 .Item Cosmic metallicity evolution of Active Galactic Nuclei: implications for optical diagnostic diagrams(Royal Astronomical Society) Dors Junior, Oli Luiz; Cardaci, Mónica Viviana; Hägele, Guilhermo Frederico; Ilha, Gabriele da Silva; Oliveira Junior, Celso Benedito de; Riffel, Rogemar André; Riffel, Rogério; Krabbe, Angela CristinaWe analyse the validity of optical diagnostic diagrams relying on emission-lines ratios and in the context of classifying Active Galactic Nuclei (AGNs) according to the cosmic metallicity evolution in the redshift range. In this regard, we fit the results of chemical evolution models (CEMs) to the radial gradients of the N/O abundances ratio derived through direct estimates of electron temperatures (Te-method) in a sample of four local spiral galaxies. This approach allows us to select representative CEMs and extrapolate the radial gradients to the nuclear regions of the galaxies in our sample, inferring in this way the central N/O and O/H abundances. The nuclear abundance predictions for theoretical galaxies from the selected CEMs, at distinct evolutionary stages, are used as input parameters in AGN photoionization models built with the Cloudy code. We found that standard BPT diagnostic diagrams are able to classify AGNs with oxygen abundances at redshift. On the other hand, the He iiλ4685/Hβ versus [N ii]λ6584/Hα diagram produces a reliable AGN classification independent of the evolutionary stage of these objects.Item AGN feedback and star formation in the peculiar galaxy NGC 232: insights from VLT-MUSE observations(Royal Astronomical Society) Souza, José Henrique Costa; Riffel, Rogemar André; Dors Junior, Oli Luiz; Riffel, Rogério; Poppe, Paulo César da RochaWe use VLT-MUSE integral field unit data to study the ionized gas physical properties and kinematics as well as the stellar populations of the Seyfert 2 galaxy NGC 232 as an opportunity to understand the role of AGN feedback on star formation. The data cover a field of view of 60 × 60 arcsec2 at a spatial resolution of ∼850 pc. The emission-line profiles have been fitted with two Gaussian components, one associated to the emission of the gas in the disc and the other due to a bi-conical outflow. The spectral synthesis suggests a predominantly old stellar population with ages exceeding 2 Gyr, with the largest contributions seen at the nucleus and decreasing outwards. Meanwhile, the young and intermediate age stellar populations exhibit a positive gradient with increasing radius and a circum-nuclear star-forming ring with radius of ∼0.5 kpc traced by stars younger than 20 Myr, is observed. This, along with the fact that AGN and SF dominated regions present similar gaseous oxygen abundances, suggests a shared reservoir feeding both star formation and the AGN. We have estimated a maximum outflow rate in ionized gas of ∼1.26 M yr−1 observed at a distance of ∼560 pc from the nucleus. The corresponding maximum kinetic power of the outflow is ∼3.4 × 1041 erg s−1. This released energy could be sufficient to suppress star formation within the ionization cone, as evidenced by the lower star formation rates observed in this region.Item Chemical abundance of LINER galaxies – metallicity calibrations based on SDSS-IV MaNGA(Royal Astronomical Society) Oliveira Junior, Celso Benedito de; Krabbe, Angela Cristina; Hernandez-Jimenez, Jose Andres; Dors Junior, Oli Luiz; Zinchenko, Igor; Hägele, Guilhermo Frederico; Cardaci, Mónica Viviana; Monteiro, Adriano FranciscoThe ionizing source of low-ionization nuclear emission-line regions (LINERs) is uncertain. Because of this, an empirical relation to determine the chemical abundances of these objects has not been proposed. In this work, for the first time, we derived two semi-empirical calibrations based on photoionization models to estimate the oxygen abundance of LINERS as a function of the N2 and O3N2 emission-line intensity ratios. These relations were calibrated using oxygen abundance estimations obtained by comparing the observational emission-line ratios of 43 LINER galaxies (taken from the MaNGA survey) and grids of photoionization models built with the cloudy code assuming post-asymptotic giant branch stars with different temperatures. We found that the oxygen abundance of LINERs in our sample is in the range, with a mean value of . We recommend the use of the N2 index to estimate the oxygen abundances of LINERs, since the calibration with this index presented a much smaller dispersion than the O3N2 index. In addition, the estimated metallicities are in good agreement with those derived by extrapolating the disc oxygen abundance gradients to the centre of the galaxies showing that the assumptions of the models are suitable for LINERs. We also obtained a calibration between the logarithm of the ionization parameter and the [O iii]/[O ii] emission-line ratio.