Disentangling the near infrared continuum spectral components of the inner 500 pc of Mrk 573: two-dimensional maps

We present a near infrared study of the spectral components of the continuum in the inner 500$\times$500 pc$^2$ of the nearby Seyfert galaxy Mrk573 using adaptive optics near-infrared integral field spectroscopy with the instrument NIFS of the Gemini North Telescope at a spatial resolution of $\sim$50 pc. We performed spectral synthesis using the {\sc starlight} code and constructed maps for the contributions of different age components of the stellar population: young ($age\leq100$ Myr), young-intermediate ($100<age\leq700$ Myr), intermediate-old ($700$ Myr $2$ Gyr) to the near-IR K-band continuum, as well as their contribution to the total stellar mass. We found that the old stellar population is dominant within the inner 250 pc, while the intermediate age components dominate the continuum at larger distances. A young stellar component contributes up to $\sim$20% within the inner $\sim$70 pc, while hot dust emission and featureless continuum components are also necessary to fit the nuclear spectrum, contributing up to 20% of the K-band flux there. The radial distribution of the different age components in the inner kiloparsec of Mrk573 is similar to those obtained by our group for the Seyfert galaxies Mrk1066, Mrk1157 and NGC1068 in previous works using a similar methodology. Young stellar populations ($\leq$100 Myr) are seen in the inner 200-300 pc for all galaxies contributing with $\ge$20% of the K-band flux, while the near-IR continuum is dominated by the contribution of intermediate-age stars ($t=$100 Myr-2 Gyr) at larger distances. Older stellar populations dominate in the inner 250 pc

The first 62 AGN observed with SDSS-IV MaNGA - IV: gas excitation and star-formation rate distributions

We present maps of the ionized gas flux distributions, excitation, star-formation rate SFR, surface mass density $\Sigma_{H+}$, and obtain total values of SFR and ionized gas masses {\it M} for 62 Active Galactic Nuclei (AGN) observed with SDSS-IV MaNGA and compare them with those of a control sample of 112 non-active galaxies. The most luminous AGN -- with L(\rm{[OIII]}\lambda 5007) \ge 3.8\times 10^{40}\,\mbox{erg}\,\mbox{s}^{-1}, and those hosted by earlier-type galaxies are dominated by Seyfert excitation within 0.2 effective radius $R_e$ from the nucleus, surrounded by LINER excitation or transition regions, while the less luminous and hosted by later-type galaxies show equally frequent LINER and Seyfert excitation within $0.2\,R_e$. The extent $R$ of the region ionized by the AGN follows the relation $R\propto\,L(\rm{[OIII]})^{0.5}$ -- as in the case of the Broad-Line Region. The SFR distribution over the region ionized by hot stars is similar for AGN and controls, while the integrated SFR -- in the range $10^{-3}-10$\,M$_\odot$\,yr$^{-1}$ is also similar for the late-type sub-sample, but higher in the AGN for 75\% of the early-type sub-sample. We thus conclude that there is no signature of AGN quenching star formation in the body of the galaxy in our sample. We also find that 66\% of the AGN have higher ionized gas masses $M$ than the controls -- in the range 10$^5-3\times10^7$\,M$_\odot$ -- while 75\% of the AGN have higher $\Sigma_{H+}$ within $0.2\,R_e$ than the control galaxies

The first 62 AGN observed with SDSS-IV MaNGA -- III: stellar and gas kinematics

We investigate the effects of Active Galactic Nuclei (AGN) on the gas kinematics of their host galaxies, using MaNGA data for a sample of 62 AGN hosts and 109 control galaxies (inactive galaxies). We compare orientation of the line of nodes (kinematic Position Angle - PA) measured from the gas and stellar velocity fields for the two samples. We found that AGN hosts and control galaxies display similar kinematic PA offsets between gas and stars. However, we note that AGN have larger fractional velocity dispersion $\sigma$ differences between gas and stars [$\sigma_{frac}=(\sigma_{\rm gas}-\sigma_{stars})/\sigma_{\rm stars}$] when compared to their controls, as obtained from the velocity dispersion values of the central (nuclear) pixel (2.5" diameter). The AGN have a median value of $\sigma_{\rm frac}$ of $_{\rm AGN}=0.04$, while the the median value for the control galaxies is $_{\rm CTR}=-0.23$. 75% of the AGN show $\sigma_{frac}>-0.13$, while 75% of the normal galaxies show $\sigma_{\rm frac}<-0.04$, thus we suggest that the parameter $\sigma_{\rm frac}$ can be used as an indicative of AGN activity. We find a correlation between the [OIII]$\lambda$5007 luminosity and $\sigma_{frac}$ for our sample. Our main conclusion is that the AGN already observed with MaNGA are not powerful enough to produce important outflows at galactic scales, but at 1-2 kpc scales, AGN feedback signatures are always present on their host galaxies.Comment: 19 pages, 8 figures, published in MNRA

Outflows in the Narrow Line Region of Bright Seyfert Galaxies - I: GMOS-IFU Data

We present two-dimensional maps of emission-line fluxes and kinematics, as well as of the stellar kinematics of the central few kpc of five bright nearby Seyfert galaxies -- Mrk\,6, Mrk\,79, Mrk\,348, Mrk\,607 and Mrk\,1058 -- obtained from observations with the Gemini Multi-Object Spectrograph (GMOS) Integral Field Unit (IFU) on the Gemini North Telescope. The data cover the inner 3\farcs5$\times$5\farcs0 -- corresponding to physical scales in the range 0.6$\times$0.9 to 1.5$\times$2.2\,kpc$^2$ -- at a spatial resolution ranging from 110 to 280 pc with a spectral coverage of 4300 -- 7100\,\AA\ and velocity resolution of $\approx$ 90\,km\,s$^{-1}$. The gas excitation is Seyfert like everywhere but show excitation, but show excitation gradients that are correlated with the gas kinematics, reddening and/or the gas density. The gas kinematics show in all cases two components: a rotation one similar to that observed in the stellar velocity field, and an outflow component. In the case of Mrk607, the gas is counter-rotating relative to the stars. Enhanced gas velocity dispersion is observed in association to the outflows according to two patterns: at the locations of the highest outflow velocities along the ionization axis or perpendicularly to it in a strip centered at the nucleus that we attribute to an equatorial outflow. Bipolar outflows are observed in Mrk\,348 and Mrk\,79, while in Mrk\,1058 only the blueshifted part is clearly observed, while in the cases of Mrk\,6 and Mrk\,607 the geometry of the outflow needs further constraints from modeling to be presented in a forthcoming study, where the mass flow rate and powers will also be obtained.Comment: 20 pages, accepted by MNRA

How well do local relations predict gas-phase metallicity gradients? Results from SDSS-IV MaNGA

Funding: J.B-B thanks IA-100420 (DGAPA-PAPIIT, UNAM) and CONA-CYT grant CF19-39578 support. RR thanks Conselho Nacional de Desenvolvimento Científico e Tecnológico ( CNPq, Proj. 311223/2020-6, 304927/2017-1 and 400352/2016-8), Fundação de amparo ’a pesquisa do Rio Grande do Sul (FAPERGS, Proj. 16/2551-0000251-7 and 19/1750-2), Coordena¸cão de Aperfei¸coamento de Pessoal de Nível Superior (CAPES, Proj. 0001). RAR acknowledges financial support from Conselho Nacional de Desenvolvimento Científico e Tecnológico (302280/2019-7).Gas-phase metallicity gradients in galaxies provide important clues to those galaxies’ formation histories. Using SDSS-IV MaNGA data, we previously demonstrated that gas metallicity gradients vary systematically and significantly across the galaxy mass–size plane: at stellar masses beyond approximately 1010 M⊙, more extended galaxies display steeper gradients (in units of dex/Re) at a given stellar mass. Here, we set out to develop a physical interpretation of these findings by examining the ability of local ∼kpc-scale relations to predict the gradient behaviour along the mass–size plane. We find that local stellar mass surface density, when combined with total stellar mass, is sufficient to reproduce the overall mass–size trend in a qualitative sense. We further find that we can improve the predictions by correcting for residual trends relating to the recent star formation histories of star-forming regions. However, we find as well that the most extended galaxies display steeper average gradients than predicted, even after correcting for residual metallicity trends with other local parameters. From these results, we argue that gas-phase metallicity gradients can largely be understood in terms of known local relations, but we also discuss some possible physical causes of discrepant gradients.PostprintPeer reviewe

Gas phase metallicity determinations in nearby AGNs with SDSS-IV MaNGA: evidence of metal poor accretion

We 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 disks 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 %each Active Galactic Nucleus (AGN) was compared to the value derived from the extrapolation of the radial oxygen abundance gradient, obtained from \ion{H}{ii} region estimates along the galaxy disk, to the central part of the host galaxies. We find that, for most of the objects ($\sim 80\,\%$), the NLR metallicity is lower than the extrapolated value, with the average difference ($$) between these estimates ranging from 0.16 to 0.30 dex. We suggest that$$ 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 ($N_{\rm e}$), [\ion{O}{iii}]$\lambda$5007 and H$\alpha$ luminosities, extinction coefficient ($A_{V})$ of the NLRs, as well as the stellar mass ($M_{*}$) of the host galaxies. Evidences of an inverse correlation between the $D$ and the parameters $N_{\rm e}$, $M_{*}$ and $A_{\rm v}$ were found

SSDSS IV MaNGA - Properties of AGN host galaxies

We present here the characterization of the main properties of a sample of 98 AGN host galaxies, both type-II and type-I, in comparison with those of about 2700 non-active galaxies observed by the MaNGA survey. We found that AGN hosts are morphologically early-type or early-spirals. For a given morphology AGN hosts are, in average, more massive, more compact, more central peaked and rather pressurethan rotational-supported systems. We confirm previous results indicating that AGN hosts are located in the intermediate/transition region between star-forming and non-star-forming galaxies (i.e., the so-called green valley), both in the ColorMagnitude and the star formation main sequence diagrams. Taking into account their relative distribution in terms of the stellar metallicity and oxygen gas abundance and a rough estimation of their molecular gas content, we consider that these galaxies are in the process of halting/quenching the star formation, in an actual transition between both groups. The analysis of the radial distributions of the starformation rate, specific star-formation rate, and molecular gas density shows that the quenching happens from inside-out involving both a decrease of the efficiency of the star formation and a deficit of molecular gas. All the intermediate data-products used to derive the results of our analysis are distributed in a database including the spatial distribution and average properties of the stellar populations and ionized gas, published as a Sloan Digital Sky Survey Value Added Catalog being part of the 14th Data Release: http://www.sdss.org/dr14/manga/manga-data/manga-pipe3d-value-added-catalog/Comment: 48 pages, 14 figures, in press in RMxA

Mapping the stellar population and gas excitation of MaNGA galaxies with MEGACUBES. Results for AGN versus control sample

We present spaxel-by-spaxel stellar population fits for the $\sim$10 thousand MaNGA datacubes. We provide multiple extension fits files, nominated as MEGACUBES, with maps of several properties as well as emission-line profiles that are provided for each spaxel. All the MEGACUBES are available through a web interface (https://manga.linea.org.br/ or http://www.if.ufrgs.br/~riffel/software/megacubes/). We also defined a final Active Galactic Nuclei (AGN) sample, as well as a control sample matching the AGN host galaxy properties. We have analysed the stellar populations and spatially resolved emission-line diagnostic diagrams of these AGNs and compared them with the control galaxies sample. We find that the relative fractions of young ($t \leq$56 Myr) and intermediate-age (100 Myr $\leq t \leq$ 2 Gyr) show predominantly a positive gradient for both AGNs and controls. The relative fraction of intermediate-age stellar population is higher in AGN hosts when compared to the control sample, and this difference becomes larger for higher [O III] luminosity AGNs. We attribute this to the fact that extra gas is available in these more luminous sources and that it most likely originates from mass-loss from the intermediate-age stars. The spatially resolved diagnostic diagrams reveal that the AGN emission is concentrated in the inner 0.5 $R_e$ (effective radius) region of the galaxies, showing that the AGN classification is aperture dependent and that emission-line ratios have to be taken together with the H$\alpha$ equivalent width for proper activity classification. We present a composite "BPT+WHAN" diagram that produces a more comprehensive mapping of the gas excitation.Comment: Accepted for publication in MNRA