arXiv subjects

Rogemar A. Riffel

Publications and source records attributed to Rogemar A. Riffel.

162 records · Page 9Linked to original sources

arXiv2011

Feeding and feedback in the active nucleus of Mrk 1157 probed with Gemini Near-Infrared Integral-Field Spectrograph

We have mapped the stellar and gaseous kinematics, as well as the emission-line flux distributions and ratios, from the inner 450pc radius of Mrk1157, using 2D near-IR spectra obtained with the Gemini NIFS at a spatial resolution of 35pc. The stellar velocity field shows a rotation pattern, with a discrete S-shaped zero velocity curve. The presence of a bar is also supported by the residual map between the observed rotation field and a model of circular orbits in a Plummer potential. The stellar velocity dispersion map presents a partial ring of low-sigma values (50-60km/s) at 250pc from the nucleus surrounded by higher sigma values from the galaxy bulge, originated in kinematically colder regions with recent star formation. The velocity dispersion of the bulge (100km/s) implies in a black hole mass of 8.3x10^6M_Sun. Emission-line flux distributions are most extended along PA=27/153deg, reaching at least 450pc from the nucleus and following the orientation observed in previous optical emission-line [OIII] imaging and radio jet. The molecular H_2 emission is dominated by thermal processes, mainly due to X-ray heating by the active nucleus. The [FeII] excitation has a larger contribution from shocks produced by the radio jet, as evidenced by the line-ratio maps and velocity dispersion map, which show spatial correlation with the radio structures. The gaseous kinematics shows two components, one due to gas located in the galaxy plane and another in outflow, which is oriented close to the plane of the sky, thus extending to high latitudes, as the galaxy plane is inclined by 45deg relative to the plane of the sky. The gas rotating in the plane dominates the H_2 and Pa-beta emission, while the gas in outflow is observed predominantly in [FeII] emission. From the outflow velocities and implied geometry, we estimate an outflow mass rate of 6M_sun/yr for the ionised gas.

astro-ph.CO↗

arXiv2010

Gas Streaming Motions towards the Nucleus of M81

We present stellar and gaseous kinematics of the inner 120x250pc^2 of the Liner/Seyfert 1 galaxy M81, from optical spectra obtained with the GMOS integral field spectrograph on the Gemini North telescope at a spatial resolution of 10pc. The stellar velocity field shows circular rotation but deviations are observed close to the minor axis which can be attributed to stellar motions possibly associated to a nuclear bar. The stellar velocity dispersion of the bulge is 162km/s leading to a black hole mass of M_BH=5.5x10^7M_sun based on the M_BH-sigma relationship. The gas kinematics is dominated by non-circular motions and the subtraction of the stellar velocity field reveals blueshifts of ~-100km/s on the far side of the galaxy and a few redshifts on the near side. These characteristics can be interpreted in terms of streaming towards the center if the gas is in the plane. On the basis of the observed velocities and geometry of the flow, we estimate a mass inflow rate in ionized gas of ~4.0x10^-3M_sun/year, which is of the order of the accretion rate necessary to power the LINER nucleus of M81. We have also applied the technique of Principal Component Analysis (PCA) to our data, which reveals the presence of a rotating nuclear gas disk within ~50pc from the nucleus and a compact outflow, approximately perpendicular to the disk. The PCA combined with the observed gas velocity field shows that the nuclear disk is being fed by gas circulating in the galaxy plane. The presence of the outflow is supported by a compact jet seen in radio observations at a similar orientation, as well as by an enhancement of the [OI]\Halpha line ratio, probably resulting from shock excitation of the circumnuclear gas by the radio jet. With these observations we are thus resolving both the feeding -- via the nuclear disk and observed gas inflow, and the feedback -- via the outflow, around the nucleus of M81.

astro-ph.CO↗

arXiv2010

Compact molecular disc and ionized gas outflows within 350 pc of the active nucleus of Mrk 1066

We present stellar and gaseous kinematics of the inner 350 pc radius of the Seyfert galaxy Mrk1066 derived from J and Kl bands data obtained with the Gemini NIFS at a spatial resolution of 35 pc. The stellar velocity field is dominated by rotation in the galaxy plane but shows an S-shape distortion along the galaxy minor axis which seems to be due to an oval structure seen in an optical continuum image. Along this oval, between 170 and 280 pc from the nucleus we find a partial ring of low sigma (~50 km/s) attributed to an intermediate age stellar population. Fro measurements of the emission-line fluxes and profiles ([PII]1.19um, [FeII]1.26um, Pa-beta and H2 2.12um), we have constructed maps for the gas centroid velocity, velocity dispersion, as well as channel maps. The velocity fields for all emission lines are dominated by a similar rotation pattern to that observed for the stars, but are distorted by the presence of two structures: (i) a compact rotating disc with radius r~70 pc; (ii) outflows along the radio jet which is oriented approximately along the galaxy major axis. The compact rotating disc is more conspicuous in the H2 emitting gas, which presents the smallest sigma values and most clear rotation pattern, supporting a location in the galaxy plane. We estimate a gas mass for the disc of ~10^7Msun. The H2 kinematics further suggests that the nuclear disc is being fed by gas coming from the outer regions. The outflow is more conspicuous in the [FeII] emitting gas, which presents the highest sigma values (up to 150 km/s) and the highest blue and redshifts of up to 500 km/s, while the highest stellar rotation velocity is only 130 km/s. We estimate a mass-outflow rate in ionized gas of 0.06 Msun/yr. The derived kinematics for the emitting gas is similar to that observed in previous studies supporting that the H2 is a tracer of the AGN feeding and the [FeII] of its feedback.

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arXiv2010

PROFIT: a new alternative for emission-line PROfile FITting

I briefly describe a simple routine for emission-line profiles fitting by Gaussian curves or Gauss-Hermite series. The PROFIT (line-PROfile FITting) routine represent a new alternative for use in fits data cubes, as those from Integral Field Spectroscopy or Fabry-Perot Interferometry, and may be useful to better study the emission-line flux distributions and gas kinematics in distinct astrophysical objects, such as the central regions of galaxies and star forming regions. The PROFIT routine is written in IDL language and is available at http://www.ufsm.br/rogemar/software.html. The PROFIT routine was used to fit the [Fe II]1.257um emission-line profiles for about 1800 spectra of the inner 350 pc of the Seyfert galaxy Mrk1066 obtained with Gemini NIFS and shows that the line profiles are better reproduced by Gauss-Hermite series than by the commonly used Gaussian curves. The two-dimensional map of the h_3 Gauss-Hermite moment shows its highest absolute values in regions close to the edge of the radio structure. These high values may be originated in an biconical outflowing gas associated with the radio jet - previously observed in the optical [O III] emission. The analysis of this kinematic component indicates that the radio jet leaves the center of the galaxy with the north-west side slightly oriented towards us and the south-east side away from us, being partially hidden by the disc of the galaxy.

astro-ph.IM↗

arXiv2010

Intermediate age stars as origin of the low velocity dispersion nuclear ring in Mrk1066

We report the first two-dimensional stellar population synthesis in the near-infrared of the nuclear region of an active galaxy, namely Mrk1066. We have used integral field spectroscopy with adaptive optics at the Gemini North Telescope to map the to map the age distribution of the stellar population in the inner 300 pc at a spatial resolution of 35 pc. An old stellar population component (age >5Gyr) is dominant within the inner ~160pc, which we attribute to the galaxy bulge. Beyond this region, up to the borders of the observation field (~300 pc), intermediate age components (0.3-0.7Gyr) dominate. We find a spatial correlation between this intermediate age component and a partial ring of low stellar velocity dispersions (sigma). Low-sigma nuclear rings have been observed in other active galaxies and our result for Mrk1066 suggests that they are formed by intermediate age stars. This age is consistent with an origin for the low-sigma rings in a past event which triggered an inflow of gas and formed stars which still keep the colder kinematics (as compared to that of the bulge) of the gas from which they have formed. At the nucleus proper we detect, in addition, two unresolved components: a compact infrared source, consistent with an origin in hot dust with mass ~1.9x10^{-2} M_Sun, and a blue featureless power-law continuum, which contributes with only ~15% of the flux at 2.12 microns.

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arXiv2010

HCN emission from the HII regions G75.78+0.34 and G75.77+0.34

We present images for the 3.5 mm continuum and HCN(J=1-0) hyperfine line emission from the surroundings of the HII regions G75.78+0.34 and G75.77+0.34 obtained with the Berkeley Illinois Maryland Association (BIMA) interferometer using the D configuration at a spatial resolution of 18 arcsec and spectral sampling of 0.34 km/s. The continuum emission of both objects is dominated by free-free emission from the ionized gas surrounding the exciting stars. Dust emission may contribute only a small fraction of the 3.5 mm continuum from G75.78+0.34 and is negligible for G75.77+0.34. The high spectral resolution reached by BIMA allowed us to separate the emission from each hyperfine transition (F=1-1, F=2-1 and F=0-1), as well as to construct velocity channel maps along each emission-line profile. The HCN flux distributions are similar to those observed for the CO emission, but with some knots of high intensities indicating that the HCN traces high density clouds not seen in CO. The HCN hyperfine line ratios for both HII regions differ from those predicted theoretically for Local Thermodynamic Equilibrium (LTE), probably due to scattering of radiation processes. The velocity channels shows that the HCN emission of G75.78+0.34 follows the bipolar molecular outflows previously observed in CO. For G75.77+0.34, the outflowing gas contributes only a small fraction of the HCN emission.

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arXiv2010

Near-IR dust and line emission from the central region of Mrk1066: Constraints from Gemini NIFS

We present integral field spectroscopy of the inner 350 pc of the Mrk1066 obtained with Gemini NIFS at a spatial resolution of 35 pc. This high spatial resolution allowed us to observe, for the first time in this galaxy, an unresolved dust concentration with mass 0.014 M_Sun, which may be part of the dusty torus. The emission-line fluxes are elongated in PA=135/315deg in agreement with the [OIII] and radio images and, except for the H lines, are brighter to the north-west than to the south-east. The H emission is stronger to the south-east, where we find a large region of star-formation. The strong correlation between the radio emission and the highest emission-line fluxes indicates that the radio jet plays a fundamental role at these intensity levels. The H2 flux is more uniformly distributed and has an excitation temperature of 2100 K. Its origin appears to be circumnuclear gas heated by X-rays from the AGN. The [FeII] emission also is consistent with X-ray heating, but with additional emission due to excitation by shocks in the radio jet. The coronal-line emission of [CaVIII] and [SIX] are unresolved by our observations indicating a distribution within 18pc from the nucleus. The reddening ranges from E(B-V) ~ 0 to E(B-V) ~ 1.7 with the highest values defining a S-shaped structure along PA ~ 135/315deg. The emission-line ratios are Seyfert-like within the ionization cone indicating that the line emission is powered by the central active nucleus in these locations. Low ionization regions are observed away from the ionization cone, and may be powered by the diffuse radiation field which filters through the ionization cone walls. Two regions at 0.5 arcsec south-east and at 1 arcsec north-west of the nucleus show starburst-like line ratios, attributed to additional emission from star forming regions.

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arXiv2009

Feeding versus Feedback in NGC4151 probed with Gemini NIFS. II. Kinematics

We have used the Gemini NIFS to map the gas kinematics of the inner 200x500pc of the Seyfert galaxy NGC4151 in the Z, J, H and K bands at a resolving power 5000 and spatial resolution of 8pc. The ionised gas emission is most extended along the known ionisation bi-cone at position angle PA=60-240deg, but is observed also along its equatorial plane. This indicates that the AGN ionizes gas beyond the borders of the bi-cone, within a sphere with 1arcsec radius around the nucleus. The ionised gas has three kinematic components: (1) one observed at the systemic velocity and interpreted as originating in the galaxy disk; (2) one outflowing along the bi-cone, with line-of-sight velocities between -600 and 600 km/s and strongest emission at +/-(100-300)km/s; (3) and another component due to the interaction of the radio jet with ambient gas. The mass outflow rate, estimated to be 1 M_Sun/yr along each cone, exceeds the inferred black hole accretion rate by a factor of 100. There is no evidence in our data for the gradual acceleration followed by gradual deceleration proposed by previous modelling of the [OIII] emitting gas. The molecular gas exhiibits distinct kinematics relative to the ionised gas. Its emission arises in extended regions approximately perpendicular to the axis of the bi-cone and along the axis of the galaxy's stellar bar, avoiding the innermost ionised regions. It does not show an outflowing component, being observed only at velocities very close to systemic, and is thus consistent with an origin in the galaxy plane. This hot molecular gas may only be the tracer of a larger reservoir of colder gas which represents the AGN feeding.

astro-ph.CO↗

arXiv2009

Feeding and Feedback in NGC 4151 from GEMINI Near Infrared Integral Field Spectroscopy

We discuss two-dimensional mapping of the near-infrared emission-line intensity distributions and kinematics of the narrow-line region (NLR) of NGC 4151, obtained with the Gemini Near-Infrared Integral Field Spectrograph, with a projected spatial resolution of ~8pc. The ionized gas intensity distribution follows the projected bi-cone morphology observed in previous optical narrow-band images, and its kinematics reveal outflows along the bi-cone. We propose a kinematic model in which the gas in the NLR moves at a velocity of ~600 km s^-1 up to ~100 pc from the nucleus. A completely distinct morphology and kinematic structure is observed for the molecular gas, which avoids the region of the bi-cone and has velocities close to systemic, and is consistent with an origin in the galaxy plane. The molecular gas thus traces the AGN feeding, while the ionized gas traces its feedback.

astro-ph.CO↗

arXiv2009

The Gemini spectral library of near-IR late type stellar templates and its application for velocity dispersion measurements

We present a spectroscopic library of late spectral type stellar templates in the near-IR range 2.15-2.42microns, at R=5300-5900 resolution, oriented to support stellar kinematics studies in external galaxies, such as the direct determination of the masses of supermassive black-holes in nearby active (or non-active) galaxies. The combination of high spectral resolution and state-of-the-art instrumentation available in 8-m class telescopes has made the analysis of circumnuclear stellar kinematics using the near-IR CO band heads one of the most used techniques for such studies, and this library aims to provide the supporting datasets required by the higher spectral resolution and larger spectral coverage currently achieved with modern near-IR spectrographs. Examples of the application for kinematical analysis are given for data obtained with two Gemini instruments, but the templates can be easily adjusted for use with other near-IR spectrographs at similar or lower resolution. The example datasets are also used to revisit the "template mismatch" effect and the dependence of the velocity dispersion values obtained from the fitting process with the characteristics of the stellar templates. The library is available in electronic form from the Gemini web pages (link above).

astro-ph.CO↗

arXiv2009

The Dusty Nuclear Torus in NGC 4151: Constraints from Gemini Near-Infrared Integral Field Spectrograph Observations

We have used a near-infrared nuclear spectrum (covering the Z, J, H and K bands) of the nucleus of NGC 4151 obtained with the Gemini Near-infrared Integral Field Spectrograph (NIFS) and adaptive optics, to isolate and constrain the properties of a near-IR unresolved nuclear source whose spectral signature is clearly present in our data. The near-IR spectrum was combined with an optical spectrum obtained with the Space Telescope Imaging Spectrograph which was used to constrain the contribution of a power-law component. After subtraction of the power-law component, the near-IR continuum is well fitted by a blackbody function, with $T=1285\pm50 $K, which dominates the nuclear spectrum -- within an aperture of radius 0$\farcs$3 -- in the near-IR. We attribute the blackbody component to emission by a dusty structure, with hot dust mass $M_{\rm HD}=(6.9\pm 1.5) \times10^{-4} {\rm M_\odot}$, not resolved by our observations, which provide only an upper limit for its distance from the nucleus of 4 pc. If the reddening derived for the narrow-line region also applies to the near-IR source, we obtain a temperature $T=1360\pm50 $K and a mass $M_{\rm HD}=(3.1\pm 0.7) \times10^{-4} {\rm M_\odot}$ for the hot dust. This structure may be the inner wall of the dusty torus postulated by the Unified Model or the inner part of a dusty wind originating in the accretion disk.

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arXiv2008

AGN-Starburst connection in NGC7582: Gemini near-infrared spectrograph integral field unit observations

We analyse two-dimensional near-IR K-band spectra from the inner 660x315 pc^2 of the Seyfert galaxy NGC7582 obtained with the Gemini GNIRS IFU. The nucleus harbors an unresolved source well reproduced by a blackbody of temperature T 1050 K, which we attribute to emission by circumnuclear dust located closer than 25 pc from the nucleus, with total mass of ~3x10^{-3}M_Sun. Surrounding the nucleus, we observe a ring of active star formation with radius of ~190 pc, an age of ~5 Myr. The radiation of the young stars in the ring accounts for at least 80 % of the ionization observed in the Brgamma emitting gas, the remaining being due to radiation emitted by the active nucleus. The stellar kinematics reveals: (1) a distorted rotation pattern in the radial velocity field with kinematic center apparently displaced from the nuclear source by a few tens of parsecs; (2) a high velocity dispersion in the bulge of sigma=170 km/s; (3) a partial ring of sigma=50 km/s interpreted as due to stars formed from cold gas in a previous burst of star formation. The kinematics of the ionized gas shows an additional blueshifted component with velocities > 100 km/s interpreted as due to an outflow along the ionization cone. The mass outflow rate in the ionized gas was estimated as ~0.05 M_Sun/yr, which is one order of magnitude larger than the accretion rate to the AGN. The flux distribution and kinematics of the hot molecular gas, traced by the H2l2.22um emission line, suggests that most of this gas is in the galactic plane. An excess blueshift along PA~-70 can be interpreted as an inflow towards the nucleus. An AGN-Starburst connection in the nucleus of NGC7582 is supported by the ratio between the mass accretion rate and the star formation rate in the circumnuclear region of ~0.26%, which is close to the Magorrian relation.

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arXiv2008

Feeding versus Feedback in NGC 4151 probed with Gemini NIFS. I. Excitation

We have used the Gemini Near-infrared Integral Field Spectrograph (NIFS) to map the emission-line intensity distributions and ratios in the Narrow-Line Region (NLR) of the Seyfert galaxy NGC 4151 in the Z, J, H and K bands at a resolving power ~ 5000, covering the inner 200 pc x 300 pc of the galaxy at a spatial resolution of 8 pc. We present intensity distributions I(r) in 14 emission lines. (1) For the ionized gas, I(r) is extended to ~ 100 pc from the nucleus along pos. angle PA=60/240 deg-- NE--SW), consistent with an origin in the known biconical outflow; while for the recombination lines I(r) ~ r^-1, for the forbidden lines I(r) is flat (r^0). (2) The H_2 emission lines intensity distributions avoid the region of the bicone, extending to r ~ 60 pc, perpendicular to the bicone axis, supporting an origin for the H_2-emitting gas in the galaxy plane. (3) The coronal lines show a steep intensity profile, described by r^-2. Using the line-ratio maps [Fe II]1.644/1.257 and Pa_b/Br_g we obtain a reddening of E(B-V)~0.5 along the NLR and E(B-V)>1 at the nucleus. Our line-ratio map [Fe II] 1.257/[P II] 1.189 is the first such map of an extragalactic source. Together with the [Fe II]/Pa_b map, these line ratios correlate with the radio intensity distribution, mapping the effects of shocks produced by the radio jet, which probably release the Fe locked in grains and produce the enhancement of the [Fe II] emission observed at ~ 1 arcsec from the nucleus. At these regions, we obtain densities N_e ~4000 cm^-3 and temperatures T_e ~ 15000K for the [Fe II]-emitting gas. For the H_2-emitting gas we obtain T ~ 2100K. The distinct intensity distributions, physical properties and locations of the ionized and molecular gas suggest that the H_2-emitting gas traces the AGN feeding, while the ionized gas traces its feedback.

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arXiv2008

Ages and metallicities of circumnuclear star formation regions from Gemini IFU observations

Aims: We derive the age and metallicity of circumnuclear star formation regions (CNSFRs) located in the spiral galaxies NGC6951 and NGC1097, and investigate the cause of the very low equivalent widths of emission lines found for these regions. Methods: We used optical two-dimensional spectroscopic data obtained with Gemini GMOS-IFUs and a grid of photoionization models to derive the the metallicities and ages of CNSFRs. Results: We find star formation rates in the range 0.002-0.14 Msun/yr and oxygen abundance of 12+log(O/H)~8.8 dex, similar to those of most metal-rich nebulae located in the inner region of galactic disks. Conclusions: We conclude that the very low emission-line equivalent widths observed in CNSFRs are caused by the ``contamination'' of the continuum by (1) contribution of the underlying bulge continuum combined with (2) contribution from previous episodes of star formation at the CNSFRs.

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arXiv2008

Mapping of the molecular gas inflow towards the Seyfert nucleus of NGC4051 using Gemini NIFS

We present two-dimensional (2D) stellar and gaseous kinematics of the inner ~130x180 pc^2 of the Narrow Line Seyfert 1 galaxy NGC4051 at a sampling of 4.5 pc, from near-infrared K-band spectroscopic observations obtained with the Gemini's Near-infrared Integral Field Spectrograph (NIFS). The turnover of the stellar rotation curve at only ~55 pc from the nucleus, revealing a highly concentrated gravitational potential. The stellar velocity dispersion of the bulge is ~60 km/s -- implying on a nuclear black hole mass of ~10^6 M_sun -- within which patches of lower velocity dispersion suggest the presence of regions of more recent star formation. The Brgamma emission-line shows no rotation as well as no blueshifts or redshifts in excess of 30 km/s, and is thus not restricted to the galaxy plane. The [CaVIII] coronal region is compact but resolved, extending over the inner 75 pc. It shows the highest blueshifts -- of up to -250 km/s, and the highest velocity dispersions, interpreted as due to outflows from the active nucleus, supporting an origin close to the nucleus. Subtraction of the stellar velocity field from the gaseous velocity field has allowed us to isolate non-circular motions observed in the H_2 emitting gas. The most conspicuous kinematic structures are two nuclear spiral arms. We interpret these structures as inflows towards the nucleus, a result similar to those of previous studies in which we have found streaming motions along nuclear spirals in ionized gas using optical IFU observations. We have calculated the mass inflow rate along the nuclear spiral arms, obtaining $\dot{M}_{H_2} ~ 4x10^{-5} M_Sun/yr, value ~100 times smaller than the accretion rate necessary to power the active nucleus.

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arXiv2007

Nuclear spirals as feeding channels to the Supermassive Black Hole: the case of the galaxy NGC 6951

We report the discovery of gas streaming motions along nuclear spiral arms towards the LINER nucleus of the galaxy NGC 6951. The observations, obtained using the GMOS integral field spectrograph on the Gemini North telescope, yielded maps of the flux distributions and gas kinematics in the Halpha, [NII]6584 and [SII]6717,31 emission lines of the inner 7x5 arcsec^2 of the galaxy. This region includes a circumnuclear star-forming ring with radius 500pc, a nuclear spiral inside the ring and the LINER nucleus. The kinematics of the ionized gas is dominated by rotation, but subtraction of a kinematic model of a rotating exponential disk reveals deviations from circular rotation within the nuclear ring which can be attributed to (1) streaming motions along the nuclear spiral arms and (2) a bipolar outflow which seems to be associated to a nuclear jet. On the basis of the observed streaming velocities and geometry of the spiral arms we estimate a mass inflow rate of ionized gas of 3x10^(-4) Msun/yr, which is of the order of the accretion rate necessary to power the LINER nucleus of NGC 6951. Similar streaming motions towards the nucleus of another galaxy with LINER nucleus -- NGC 1097 -- have been reported by our group in a previous paper. Taken together, these results support a scenario in which nuclear spirals are channels through which matter is transferred from galactic scales to the nuclear region to feed the supermassive black hole.

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arXiv2006

Gemini Near Infrared Integral Field Spectroscopy of the Narrow-Line Region of ESO428-G14: kinematics, excitation and the role of the radio jet

We present 2D gas kinematics and excitation of the inner 300 pc of the Seyfert galaxy ESO428-G14 at a sampling of 14 pc^2, from near-IR spectroscopic observations at R~6000 obtained with the IFU of the Gemini Near-Infrared Spectrograph. From measurements of fluxes and profiles of the emission lines [FeII]lambda1.257, Pa_beta, H_2lambda2.121 and Br_gamma, we construct 2D maps of line intensities and ratios, radial velocities and velocity dispersions. Emission lines "tomography" is provided by velocity slices obtained across the line profiles, which allows the mapping of not only of peak velocities but including also the wings. We compare these maps with a previously published high spatial resolution radio map and find a tight relation between the radio structure and the emission-line flux distributions and kinematics, revealing that the radio-jet plays a fundamental role not only in shaping the NLR but also in the imprint of its kinematics. Blueshifts of up to 400 km/s and velocity dispersions of up to 150 km/s are observed in association with the radio jet at position angle PA=129, which is also the PA of the photometric major axis of the galaxy. The [FeII] shows the largest blueshifts and velocity dispersions and its flux distribution is concentrated along the jet, while the H_2 shows the lowest velocity dispersions and has additional flux contribution from regions beyond the jet. We use the 2D velocity dispersion maps to estimate upper limits to the contribution of the radio jet to the excitation of [FeII] and H_2 which may reach 90% for [FeII] and 80% for H_2 in the jet region. The [FeII]/Pa_beta emission-line ratios and the association of the [FeII] flux distribution and kinematics with the radio structure supports a stronger contribution of the radio jet to the [FeII] excitation than to that of H_2.

astro-ph↗

arXiv2006

Streaming Motions Towards the Supermassive Black Hole in NGC 1097

We have used GMOS-IFU and high resolution HST-ACS observations to map, in unprecedented detail, the gas velocity field and structure within the 0.7 kpc circumnuclear ring of the SBb LINER/Seyfert 1 galaxy NGC 1097. We find clear evidence of radial streaming motions associated with spiral structures leading to the unresolved (<3.5 parsecs) nucleus, which we interpret as part of the fueling chain by which gas is transported to the nuclear starburst and supermassive black hole.

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