arXiv subjects

Rogemar A. Riffel

Publications and source records attributed to Rogemar A. Riffel.

At least 109 records · Page 6Linked to original sources

arXiv2019

SDSS IV MaNGA -- Star-Formation Driven Biconical Outflows in the Local Univers

We present a sample of 48 nearby galaxies with central, biconical outflows identified by the Mapping Nearby Galaxies at APO (MaNGA) survey. All considered galaxies have star formation driven bi-conical central outflows (SFB), with no signs of AGN. We find that the SFB outflows require high central concentration of the star formation rate. This increases the gas velocity dispersion over the equilibrium limit and helps maintain the gas outflows. The central starbursts increase the metallicity, extinction, and the alpha/Fe ratio in the gas. Significant amount of young stellar population at the centers suggests that the SFBs are associated with the formation of young bulges in galaxies. More than 70% of SFB galaxies are group members or have companions with no prominent interaction, or show asymmetry of external isophotes. In 15% SFB cases stars and gas rotate in the opposite directions, which points at the gas infall from satellites as the primary reason for triggering the SFB phenomena.

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arXiv2019

HI-MaNGA: HI Followup for the MaNGA Survey

We present the HI-MaNGA programme of HI follow-up for the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey. MaNGA, which is part of the Fourth phase of the Sloan Digital Sky Surveys (SDSS-IV), is in the process of obtaining integral field unit (IFU) spectroscopy for a sample of ~10,000 nearby galaxies. We give an overview of the HI 21cm radio follow-up observing plans and progress and present data for the first 331 galaxies observed in the 2016 observing season at the Robert C. Bryd Green Bank Telescope (GBT). We also provide a cross match of the current MaNGA (DR15) sample with publicly available HI data from the Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) survey. The addition of HI data to the MaNGA data set will strengthen the survey's ability to address several of its key science goals that relate to the gas content of galaxies, while also increasing the legacy of this survey for all extragalactic science.

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arXiv2019

Outflows, Inflows and Young Stars in the inner 200 pc of the Seyfert galaxy NGC 2110

We present a two-dimensional mapping of stellar population age components, emission-line fluxes, gas excitation and kinematics within the inner $\sim200$ pc of the Seyfert 2 galaxy NGC 2110. We used the Gemini North Integral Field Spectrograph (NIFS) in the J and K bands at a spatial resolution of $\sim22$ pc. The unresolved nuclear continuum is originated in combined contributions of young stellar population (SP; age$\leq100$ Myr), a featureless AGN continuum and hot dust emission. The young-intermediate SP ($100<$age$\leq700$ Myr) is distributed in a ring-shaped structure at $\approx140$ pc from the nucleus, which is roughly coincident with the lowest values of the stellar velocity dispersion. In the inner $\approx115$ pc the old SP (age$>2$ Gyr) is dominant. The [FeII]1.25$μ$m emission-line flux distribution is correlated with the radio emission and its kinematics comprise two components, one from gas rotating in the galaxy plane and another from gas in outflow within a bicone oriented along north-south. These outflows seem to originate in the interaction of the radio jet with the ambient gas producing shocks that are the main excitation mechanism of the [FeII] emission. We estimate: (1) an ionized gas mass outflow rate of $\sim0.5$ M$_\odot$/yr at $\sim$70 pc from the nucleus; and (2) a kinetic power for the outflow of only 0.05% of the AGN bolometric luminosity implying weak feedback effect on the galaxy.

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arXiv2019

What drives the velocity dispersion of ionized gas in star-forming galaxies?

We analyze the intrinsic velocity dispersion properties of 648 star-forming galaxies observed by the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, to explore the relation of intrinsic gas velocity dispersions with star formation rates (SFRs), SFR surface densities ($\rm{Σ_{SFR}}$), stellar masses and stellar mass surface densities ($\rm{Σ_{*}}$). By combining with high z galaxies, we found that there is a good correlation between the velocity dispersion and the SFR as well as $\rm{Σ_{SFR}}$. But the correlation between the velocity dispersion and the stellar mass as well as $\rm{Σ_{*}}$ is moderate. By comparing our results with predictions of theoretical models, we found that the energy feedback from star formation processes alone and the gravitational instability alone can not fully explain simultaneously the observed velocity-dispersion/SFR and velocity-dispersion/$\rm{Σ_{SFR}}$ relationships.

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arXiv2019

Optical/NIR stellar absorption and emission-line indices from luminous infrared galaxies

We analyze a set of optical-to-near-infrared long-slit nuclear spectra of 16 infrared-luminous spiral galaxies. All of the studied sources present H$_2$ emission, which reflects the star-forming nature of our sample, and they clearly display H I emission lines in the optical. Their continua contain many strong stellar absorption lines, with the most common features due to Ca I, Ca II, Fe I, Na I, Mg I, in addition to prominent absorption bands of TiO, VO, ZrO, CN and CO. We report a homogeneous set of equivalent width (EW) measurements for 45 indices, from optical to NIR species for the 16 star-forming galaxies as well as for 19 early type galaxies where we collected the data from the literature. This selected set of emission and absorption-feature measurements can be used to test predictions of the forthcoming generations of stellar population models. We find correlations among the different absorption features and propose here correlations between optical and NIR indices, as well as among different NIR indices, and compare them with model predictions. While for the optical absorption features the models consistently agree with the observations,the NIR indices are much harder to interpret. For early-type spirals the measurements agree roughly with the models, while for star-forming objects they fail to predict the strengths of these indices.

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arXiv2019

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 $Σ_{H+}$, 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 $L(\rm{[OIII]}λ5007) \ge 3.8\times 10^{40}\,\mbox{erg}\,\mbox{s}^{-1}$, 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 $Σ_{H+}$ within $0.2\,R_e$ than the control galaxies.

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arXiv2019

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 $σ$ differences between gas and stars [$σ_{frac}=(σ_{\rm gas}-σ_{stars})/σ_{\rm stars}$] 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 $σ_{\rm frac}$ of $<σ_{frac}>_{\rm AGN}=0.04$, while the the median value for the control galaxies is $<σ_{frac}>_{\rm CTR}=-0.23$. 75% of the AGN show $σ_{frac}>-0.13$, while 75% of the normal galaxies show $σ_{\rm frac}<-0.04$, thus we suggest that the parameter $σ_{\rm frac}$ can be used as an indicative of AGN activity. We find a correlation between the [OIII]$λ$5007 luminosity and $σ_{frac}$ 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.

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arXiv2019

Gemini NIFS survey of feeding and feedback in nearbyActive Galaxies - III. Ionized versus warm molecular gasmasses and distributions

We have used the Gemini Near-Infrared Integral Field Spectrograph (NIFS) in the J and K bands to map the distribution, excitation and kinematics of the ionized HII and warm molecular gas H$_2$, in the inner few 100 pc of 6 nearby active galaxies: NGC 788, Mrk 607, NGC 3227, NGC 3516, NGC 5506, NGC 5899. {For most galaxies, this is the first time that such maps have been obtained}. The ionized and H$_2$ gas show distinct kinematics: while the H$_2$ gas is mostly rotating in the galaxy plane with low velocity dispersion ($σ$), the ionized gas usually shows signatures of outflows associated with higher $σ$ values, most clearly seen in the [FeII] emission line. These two gas species also present distinct flux distributions: the H$_2$ is more uniformly spread over the whole galaxy plane, while the ionized gas is more concentrated around the nucleus and/or collimated along the ionization axis of its Active Galactic Nucleus (AGN), presenting a steeper gradient in the average surface mass density profile than the H$_2$ gas. The total HII masses cover the range $2\times10^5-2\times10^7$ M$_{\odot}$, with surface mass densities in the range 3-150 M$_{\odot}$ pc$^{-2}$, while for the warm H$_2$ the values are 10$^{3-4}$ times lower. We estimate that the available gas reservoir is at least $\approx$ 100 times more massive than needed to power the AGN. If this gas form new stars the star-formation rates, obtained from the Kennicutt-schmidt scalling relation, are in the range 1-260$\times$ 10$^{-3}$ M$_{\odot}$ yr$^{-1}$. But the gas will also - at least in part - be ejected in the form of the observed otflows.

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arXiv2019

Precessing winds from the nucleus of the prototype Red Geyser?

Super-massive black holes (SMBH) are present at the center of most galaxies, with the related mass accretion processes giving origin to outflows in Active Galactic Nuclei (AGN). It has been presumed that only intense winds from luminous AGN were able to suppress star formation until the discovery of a new class of galaxies with no recent star formation and with the nucleus in a quiescent state showing kpc scale outflows. We used SDSS MaNGA and Gemini Integral Field Spectroscopy of the prototype Red Geyser Akira and found that the orientation of the outflow changes by about 50$^\circ$ from its nucleus to kpc scales. A possible interpretation is that the outflow is produced by a precessing accretion disk due to a misalignment between the orientation of the disk and the spin of the SMBH. The precession of the central source is also supported by a similar change in the orientation of the ionization pattern. Although similar behavior has commonly being reported for collimated relativistic jets, the precession of an AGN wide wind is reported here for the first time, implying on a larger work surface of the wind, which in turn increases the star formation suppression efficiency of the outflow.

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arXiv2019

A close look at the dwarf AGN of NGC 4395: optical and near-IR integral field spectroscopy

Intermediate mass black holes (10$^3$-10$^5$ M$_\odot$) in the center of dwarf galaxies are believed to be analogous to growing Active Galactic Nuclei (AGN) in the early Universe. Their characterization can provide insight about the early galaxies. We present optical and near-infrared integral field spectroscopy of the inner $\sim$50 pc of the dwarf galaxy NGC4395, known to harbor an AGN. NGC 4395 is an ideal candidate to investigate the nature of dwarf AGN, as it is nearby ($d\approx4.4$ Mpc) enough to allow a close look at its nucleus. The optical data were obtained with the Gemini GMOS-IFU covering the 4500 A to 7300 A spectral range at a spatial resolution of 10 pc. The J and K-band spectra were obtained with the Gemini NIFS at spatial resolutions of $\sim$5 pc. The gas kinematics show a compact, rotation disk component with a projected velocity amplitude of 25 km s$^{-1}$. We estimate a mass of $7.7\times10^5$ M$_\odot$ inside a radius of 10 pc. From the H$α$ broad line component, we estimate the AGN bolometric luminosity as $L_{ bol}=(9.9\pm1.4)\times10^{40}$ erg s$^{-1}$ and a mass $M_{ BH}=(2.5^{+1.0}_{-0.8})\times10^5$ M$_\odot$ for the central black hole. The mean surface mass densities for the ionized and molecular gas are in the ranges (1-2) M$_{\odot} $pc$^{-2}$ and (1-4)$\times10^{-3}$ M${_\odot}$ pc$^{-2}$ and the average ratio between ionized and hot molecular gas masses is $\sim$500. The emission-line flux distributions reveal an elongated structure at 24 pc west of the nucleus, which is blueshifted relative to the systemic velocity of the galaxy by $\approx$30 km s$^{-1}$. We speculate that this structure is originated by the accretion of a gas-rich small satellite or by a low metallicity cosmic cloud.

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arXiv2018

Morphology of AGN Emission Line Regions in SDSS-IV MaNGA Survey

Extended narrow-line regions (NLRs) around active galactic nuclei (AGN) are shaped by the distribution of gas in the host galaxy and by the geometry of the circumnuclear obscuration, and thus they can be used to test the AGN unification model. In this work, we quantify the morphologies of the narrow-line regions in 308 nearby AGNs ($z=0-0.14$, \lbol $\sim 10^{42.4-44.1}$ \erg{}) from the MaNGA survey. Based on the narrow-line region maps, we find that a large fraction (81\%) of these AGN have bi-conical NLR morphology. The distribution of their measured opening angles suggests that the intrinsic opening angles of the ionization cones has a mean value of 85--98$^\circ$ with a finite spread of 39-44$^\circ$ (1-$σ$). Our inferred opening angle distribution implies a number ratio of type I to type II AGN of 1:1.6--2.3, consistent with other measurements of the type I / type II ratio at low AGN luminosities. Combining these measurements with the WISE photometry data, we find that redder mid-IR color (lower effective temperature of dust) corresponds to stronger and narrower photo-ionized bicones. This relation is in agreement with the unification model that suggests that the bi-conical narrow-line regions are shaped by a toroidal dusty structure within a few pc from the AGN. Furthermore, we find a significant alignment between the minor axis of host galaxy disks and AGN ionization cones. Together, these findings suggest that obscuration on both circumnuclear ($\sim $pc) and galactic ($\sim$ kpc) scales are important in shaping and orienting the AGN narrow-line regions.

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arXiv2018

Detecting Radio-AGN signatures in Red geysers

A new class of quiescent galaxies harboring possible AGN-driven winds has been discovered using spatially resolved optical spectroscopy from the ongoing SDSS-IV MaNGA survey. These galaxies, termed "red geysers", constitute $5-10\%$ of the local quiescent population and are characterized by narrow bisymmetric patterns in ionized gas emission features. Cheung et al. argued that these galaxies host large-scale AGN-driven winds that may play a role in suppressing star formation at late times. In this work, we test the hypothesis that AGN activity is ultimately responsible for the red geyser phenomenon. We compare the nuclear radio activity of the red geysers to a matched control sample with similar stellar mass, redshift, rest frame $NUV-r$ color, axis ratio and presence of ionized gas. We have used the 1.4 GHz radio continuum data from VLA FIRST survey to stack the radio flux from the red geyser and control samples. In addition to a 3 times higher FIRST detection rate, we find that red geysers have a 5$σ$ higher level of average radio flux than control galaxies. After restricting to rest-frame $NUV-r$ color $>$ 5 and checking mid-IR WISE photometry, we rule out star formation contamination and conclude that red geysers are associated with more active AGN. Red geysers and a possibly-related class with disturbed H$α$ emission account for 40\% of all radio-detected red galaxies with $\rm log~(M_\star/M_\odot) < 11$. Our results support a picture in which episodic AGN activity drives large-scale-relatively weak ionized winds that may provide a feedback mechanism for many early-type galaxies.

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arXiv2018

Mildly Suppressed Star Formation in Central Regions of MaNGA Seyfert Galaxies

Negative feedback from accretion onto super-massive black holes (SMBHs), that is to remove gas and suppress star formation in galaxies, has been widely suggested. However, for Seyfert galaxies which harbor less active, moderately accreting SMBHs in the local universe, the feedback capability of their black hole activity is elusive. We present spatially-resolved H$α$ measurements to trace ongoing star formation in Seyfert galaxies and compare their specific star formation rate with a sample of star-forming galaxies whose global galaxy properties are controlled to be the same as the Seyferts. From the comparison we find that the star formation rates within central kpc of Seyfert galaxies are mildly suppressed as compared to the matched normal star forming galaxies. This suggests that the feedback of moderate SMBH accretion could, to some extent, regulate the ongoing star formation in these intermediate to late type galaxies under secular evolution.

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arXiv2018

Outflows in the Seyfert 2 galaxy NGC5643 traced by the [SIII] emission

We use Gemini Multi-Object Spectrograph (GMOS) Integral Field Unit (IFU) observations of the inner 285$\times$400 pc$^2$ region of the Seyfert 2 galaxy NGC 5643 to map the [SIII]$\lambda9069$ emission-line flux distribution and kinematics, as well as the stellar kinematics, derived by fitting the CaII$λλλ$8498,8542,8662 triplet, at a spatial resolution of 45 pc. The stellar velocity field shows regular rotation, with a projected velocity of 100 km/s and kinematic major axis along Position Angle $PA=-36^\circ$. A ring of low stellar velocity dispersion values ($\sim$70 km/s), attributed to young/intermediate age stellar populations, is seen surrounding the nucleus with radius of 50 pc. We found that the [SIII] flux distribution shows an elongated structure along the east-west direction and its kinematics is dominated by outflows within a bi-cone at an ionized gas outflow rate of 0.3 M$_\odot$ yr$^{-1}$. In addition, velocity slices across the [SIII]$\lambda9069$ emission-line reveal a kinematic component attributed to rotation of gas in the plane of the galaxy.

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arXiv2018

The fiftieth anniversary of physics at UFSM: a gender analysis of graduates

The Federal University of Santa Maria (UFSM - Universidade Federal de Santa Maria) has trained more than 600 undergraduate and 200 Ph.D. students, becoming a reference in physics training at the Rio Grande do Sul central region. In this work we present a gender analysis of the UFSM graduated students from both levels. The number of graduated students of the female gender has been rising with time and is significatively bigger than the number observed nationally in both levels. The mean values are 35%, 37%, 28%, 42% e 39% for the courses physics teaching (daytime), physics teaching (nightime), physics, master and doctorate, respectively. We also observe an increase in the participation of female students in graduate courses, when comparing to undergraduate courses, unlike what is observed in the national average numbers. Considering only the last 5 years the number of graduated students reaches 50% in the physics teaching (daytime) and master courses. Although this study is of a local nature, it reinforces the need for the dissemination of data regarding the gender of graduates by all universities, allowing to conduct general gender studies.

physics.ed-ph↗

arXiv2018

Star formation and gas inflows in the OH Megamaser galaxy IRAS03056+2034

We have obtained observations of the OH Megamaser galaxy IRAS03056+0234 using Gemini Multi-Object Spectrograph (GMOS) Integral Field Unit (IFU), Very Large Array (VLA) and Hubble Space Telescope (HST). The HST data reveals spiral arms containing knots of emission associated to star forming regions. The GMOS-IFU data cover the spectral range of 4500 to 7500 Å at a velocity resolution of 90 km s$^{-1}$ and spatial resolution of 506 pc. The emission-line flux distributions reveal a ring of star forming regions with radius of 786 pc centred at the nucleus of the galaxy, with an ionized gas mass of 1.2$\times$ 10$^{8}$M$_{\odot}$, an ionizing photon luminosity of log Q[H$^{+}$]=53.8 and a star formation rate of 4.9 M$_{\odot}$ yr$^{-1}$. The emission-line ratios and radio emission suggest that the gas at the nuclear region is excited by both starburst activity and an active galactic nucleus. The gas velocity fields are partially reproduced by rotation in the galactic plane, but show, in addition, excess redshifts to the east of the nucleus, consistent with gas inflows towards the nucleus, with velocity of $\sim$45 km s$^{-1}$ and a mass inflow rate of $\sim$7.7$\times$10$^{-3}$ M$_{\odot}$ yr$^{-1}$.

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arXiv2018

The complex jet- and bar-perturbed kinematics in NGC 3393 as revealed with ALMA and GEMINI-GMOS/IFU

NGC 3393, a nearby Seyfert 2 galaxy with nuclear radio jets, large-scale and nuclear bars, and a posited secondary super massive black hole, provides an interesting laboratory to test the physics of inflows and outflows. Here we present and analyse the molecular gas (ALMA observations of CO J:2-1 emission over a field of view (FOV) of 45\arcsec \times 45\arcsec, at 0\farcs56 (143 pc) spatial and 5 km/s spectral resolution), ionised gas and stars (GEMINI-GMOS/IFU; over a FOV of 4\arcsec \times 5\arcsec, at 0\farcs62 (159 pc) spatial and 23 km/s spectral resolution) in NGC 3393. The ionised gas emission, detected over the complete GEMINI-GMOS FOV, has three identifiable kinematic components. A narrow (σ< 115 km/s) component present in the complete FOV, which is consistent with rotation in the galaxy disk. A broad (σ> 115 km/s) redshifted component, detected near the NE and SW radio lobes; which we interpret as a radio jet driven outflow. And a broad (σ> 115 km/s) blueshifted component that shows high velocities in a region perpendicular to the radio jet axis; we interpret this as an equatorial outflow. The CO J:2-1 emission is detected in spiral arms on 5\arcsec - 20\arcsec scales, and in two disturbed circumnuclear regions. The molecular kinematics in the spiral arms can be explained by rotation. The highly disturbed kinematics of the inner region can be explained by perturbations induced by the nuclear bar and interactions with the large scale bar. We find no evidence for, but cannot strongly rule out, the presence of the posited secondary black hole.

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arXiv2018

The first 62 AGN observed with SDSS-IV MaNGA - II: resolved stellar populations

We present spatially resolved stellar population age maps, average radial profiles and gradients for the first 62 Active Galactic Nuclei (AGN) observed with SDSS-IV MaNGA to study the effects of the active nuclei on the star formation history of the host galaxies. These results, derived using the STARLIGHT code, are compared with a control sample of non-active galaxies matching the properties of the AGN hosts. We find that the fraction of young stellar populations (SP) in high-luminosity AGN is higher in the inner ($R \leq 0.5\,R_e$) regions when compared with the control sample; low-luminosity AGN, on the other hand, present very similar fractions of young stars to the control sample hosts for the entire studied range ($1\,R_e$). The fraction of intermediate age SP of the AGN hosts increases outwards, with a clear enhancement when compared with the control sample. The inner region of the galaxies (AGN and control galaxies) presents a dominant old SP, whose fraction decreases outwards. We also compare our results (differences between AGN and control galaxies) for the early and late-type hosts and find no significant differences. In summary, our results suggest that the most luminous AGN seems to have been triggered by a recent supply of gas that has also triggered recent star formation ($t\,\leq\,40\,Myrs$) in the central region.

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