We present optical integral field spectroscopy of the circum-nuclear gas of the Seyfert 2 galaxy NGC 1386. The data cover the central 7$^{primeprime} times 9^{primeprime}$ (530 $times$ 680 pc) at a spatial resolution of 0.9 (68 pc), and the spectral
range 5700-7000 AA at a resolution of 66 km s$^{-1}$. The line emission is dominated by a bright central component, with two lobes extending $approx$ 3$^{primeprime}$ north and south of the nucleus. We identify three main kinematic components. The first has low velocity dispersion ($bar sigma approx $ 90 km s$^{-1}$), extends over the whole field-of-view, and has a velocity field consistent with gas rotating in the galaxy disk. We interpret the lobes as resulting from photoionization of disk gas in regions where the AGN radiation cones intercept the disk. The second has higher velocity dispersion ($bar sigma approx$ 200 km s$^{-1}$) and is observed in the inner 150 pc around the continuum peak. This component is double peaked, with redshifted and blueshifted components separated by $approx$ 500 km s$^{-1}$. Together with previous HST imaging, these features suggest the presence of a bipolar outflow for which we estimate a mass outflow rate of $mathrm{dot M} gtrsim $ 0.1 M$_{odot}$ yr$^{-1}$. The third component is revealed by velocity residuals associated with enhanced velocity dispersion and suggests that outflow and/or rotation is occurring approximately in the equatorial plane of the torus. A second system of velocity residuals may indicate the presence of streaming motions along dusty spirals in the disk.
NGC 4258 is the galaxy with the most accurate (maser-based) determination for the mass of the supermassive black hole (SMBH) in its nucleus. In this work we present a two-dimensional mapping of the stellar kinematics in the inner 3.0 x 3.0 arcsec = 1
00 x 100 pc of NGC 4258 using adaptative-optics observations obtained with the Near-Infrared Integral Field Spectrograph of the GEMINI North telescope at a 0.11 arcsec (4 pc) angular resolution. The observations resolve the radius of influence of the SMBH, revealing an abrupt increase in the stellar velocity dispersion within 10 pc from the nucleus, consistent with the presence of a SMBH there. Assuming that the galaxy nucleus is in a steady state and that the velocity dispersion ellipsoid is aligned with a cylindrical coordinate system, we constructed a Jeans anisotropic dynamical model to fit the observed kinematics distribution. Our dynamical model assumes that the galaxy has axial symmetry and is constructed using the multi-gaussian expansion method to parametrize the observed surface brightness distribution. The Jeans dynamical model has three free parameters: the mass of the central SMBH, the mass-luminosity ratio of the galaxy and the anisotropy of the velocity distribution. We test two types of models: one with constant velocity anisotropy, and another with variable anisotropy. The model that best reproduces the observed kinematics was obtained considering that the galaxy has radially varying anisotropy, being the best-fitting parameters with 3$sigma$ significance $M_bullet=4.8^{+0.8}_{-0.9}times 10^7,{rm M_odot}$ and $Gamma_k = 4.1^{+0.4}_{-0.5}$. This value for the mass of the SMBH is just 25 per cent larger than that of the maser determination and 50 per cent larger that a previous stellar dynamical determination obtained via Schwarzschild models.
We present two-dimensional gaseous kinematics of the inner 1.1 x 1.6kpc^2 of the Seyfert 2 galaxy NGC2110, from optical spectra obtained with the GMOS integral field spectrograph on the Gemini South telescope at a spatial resolution of 100pc. Gas emi
ssion is observed over the whole field-of-view, with complex - and frequently double - emission-line profiles. We have identified four components in the emitting gas, according to their velocity dispersion (sigma), which we refer to as: (1) warm gas disk (sigma = 100-220km/s); (2) cold gas disk (sigma = 60-90km/s); (3) nuclear component (sigma = 220-600km/s); and (4) northern cloud (sigma = 60-80km/s). Both the cold and warm disk components are dominated by rotation and have similar gas densities, but the cold gas disk has lower velocity dispersions and reaches higher rotation velocities. We attribute the warm gas disk to a thick gas layer which encompasses the cold disk as observed in some edge-on spiral galaxies. After subtraction of a rotation model from the cold disk velocity field, we observe excess blueshifts of 50km/s in the far side of the galaxy as well as similar excess redshifts in the near side. These residuals can be interpreted as due to nuclear inflow in the cold gas, with an estimated ionized gas mass inflow rate of 2.2 x 10^(-2)Msun/yr. We have also subtracted a rotating model from the warm disk velocity field and found excess blueshifts of 100km/s to the SW of the nucleus and excess redshifts of 40km/s to the NE, which we attribute to gas disturbed by an interaction with a nuclear spherical outflow. This nuclear outflow is the origin of the nuclear component observed within the inner 300pc and it has a mass outflow rate of 0.9Msun/yr. In a region between 1 and 4 north of the nucleus we find a new low sigma component of ionized gas which we attribute to a high latitude cloud photoionized by the nuclear source.
We present a two-dimensional analysis of the gaseous excitation and kinematics of the inner 2.5 x 1.7 kpc^2 of the LINER/Seyfert 1 galaxy Arp 102B, from optical spectra obtained with the GMOS integral field spectrograph on the Gemini North telescope
at a spatial resolution of 250 pc. Emission-line flux maps show the same two-armed nuclear spiral we have discovered in previous observations with the HST-ACS camera. One arm reaches 1 kpc to the east and the other 500 pc to the west, with a 8.4 GHz VLA bent radio jet correlating with the former. The gas density is highest (500 - 900 cm^(-3)) at the nucleus and in the northern border of the east arm, at a region where the radio jet seems to be deflected. Channel maps show blueshifts but also some redshifts at the eastern arm and jet location which can be interpreted as originated in the front and back walls of an outflow pushed by the radio jet, suggesting also that the outflow is launched close to the plane of the sky. We estimate a mass outflow rate along the east arm of 0.26 - 0.32 Msun yr^(-1) (depending on the assumed outflow geometry), which is between one and two orders of magnitude higher than the mass accretion rate to the active nucleus, implying that there is mass-loading of the nuclear outflow from circumnuclear gas. The power of this outflow is 0.06 - 0.3%Lbol. We propose a scenario in which gas has been recently captured by Arp 102B in an interaction with Arp 102A, settling in a disk rotating around the nucleus of Arp 102B and triggering its nuclear activity. A nuclear jet is pushing the circumnuclear gas, giving origin to the nuclear arms. A blueshifted emitting gas knot is observed at 300 pc south-east from the nucleus and can be interpreted as another (more compact) outflow, with a possible counterpart to the north-west.
We use near-infrared spectroscopic data from the inner few hundred parsecs of a sample of 47 active galaxies to investigate possible correlations between the stellar velocity dispersion (sigma_star), obtained from the fit of the K-band CO stellar abs
orption bands, and the gas velocity dispersion (sigma) obtained from the fit of the emission-line profiles of [SIII]0.953um, [Fe II]1.257um, [FeII]1.644um and H_2 2.122um. While no correlations with sigma_star were found for H_2 and [SIII], a good correlation was found for the two [Fe II] emission lines, expressed by the linear fit sigma_star = 95.4pm16.1 + (0.25pm0.08)sigma_[Fe II]. Excluding barred objects from the sample a better correlation is found between sigma_star and sigma_[FeII], with a correlation coefficient of R=0.80 and fitted by the following relation: sigma_star = 57.9pm23.5 + (0.42pm0.10)sigma_[FeII]. This correlation can be used to estimate $sigma_star$ in cases it cannot be directly measured and the [FeII] emission lines are present in the spectra, allowing to obtain the mass of the supermassive black hole (SMBH) from the M-sigma_star relation. The scatter from a one-to-one relationship between sigma_star and its value derived from sigma_[FeII] using the equation above for our sample is 0.07dex, which is smaller than that obtained in previous studies which use sigma_[OIII] in the optical as a proxy for sigma_star. The use of sigma_[Fe,II] in the near-IR instead of sigma_[OIII] in the optical is a valuable option for cases in which optical spectra are not available or are obscured, as is the case of many AGN.
The broad (FWHM ~ 10,000 km/s) double-peaked H{alpha} profile from the LINER/Seyfert 1 nucleus of NGC 1097 was discovered in 1991, and monitored for the following 11 years. The profile showed variations attributed to the rotation of gas in a non-axis
ymmetric Keplerian accretion disk, ionized by a varying radiatively inefficient accretion flow (RIAF) located in the inner parts of the disk. We present and model 11 new spectroscopic observations of the double-peaked profile taken between 2010 March and 2011 March. This series of observations was motivated by the finding that in 2010 March the flux in the double-peaked line was again strong, becoming, in 2010 December, even stronger than in the observations of a decade ago. We also discovered shorter timescale variations than in the previous observations: (1) the first, of ~7 days, is interpreted as due to reverberation of the variation of the ionizing source luminosity, and the timescale of 7 days as the light crossing time between the source and the accretion disk; this new timescale and its interpretation provides a distance between the emitting gas and the supermassive black hole and as such introduces a new constraint on its mass; (2) the second, of approximately 5 months, was attributed to the rotation of a spiral arm in the disk, which was found to occur on the dynamical timescale. We use two accretion disk models to fit theoretical profiles to the new data, both having non-axisymmetric emissivities produced by the presence of an one-armed spiral. Our modeling constrains the rotation period for the spiral to be approximately 18 months. This work supports our previous conclusion that the broad double-peaked Balmer emission lines in NGC 1097, and probably also in other low-luminosity active nuclei, originate from an accretion disk ionized by a central RIAF.
We report the discovery of a two-armed mini-spiral structure within the inner kiloparsec of the E0 LINER/Seyfert 1 galaxy Arp102B. The arms are observed in H-alpha emission and located East and West of the nucleus, extending up to about 1 kpc from it
. We use narrow-band imaging from the Hubble Space Telescope Advanced Camera for Surveys, in combination with archival VLA radio images at 3.6 and 6 cm to investigate the origin of the nuclear spiral. From the H-alpha luminosity of the spiral, we obtain an ionized gas mass of the order of one million solar masses. One possibility is that the nuclear spiral represents a gas inflow triggered by a recent accretion event which has replenished the accretion disk, giving rise to the double-peaked emission-line profiles characteristic of Arp102B. However, the radio images show a one-sided curved jet which correlates with the eastern spiral arm observed in the H-alpha image. A published milliarcsecond radio image also shows one-sided structure at position angle about 40 degrees, approximately aligned with the inner part of the eastern spiral arm. The absence of a radio counter-part to the western spiral arm is tentatively interpreted as indicating that the jet is relativistic, with an estimated speed of 0.45c. Estimates of the jet kinetic energy and the ionizing luminosity of the active nucleus indicate that both are capable of ionizing the gas along the spiral arms. We conclude that, although the gas in the nuclear region may have originated in an accretion event, the mini-spiral is most likely the result of a jet-cloud interaction rather than an inflowing stream.
I report recent results on the kinematics of the inner few hundred parsecs (pc) around nearby active galactic nuclei (AGN) at a sampling of a few pc to a few tens of pc, using optical and near-infrared (near-IR) integral field spectroscopy obtained w
ith the Gemini telescopes. The stellar kinematics of the hosts - comprised mostly of spiral galaxies - are dominated by circular rotation in the plane of the galaxy. Inflows with velocities of ~ 50 km/s have been observed along nuclear spiral arms in (optical) ionized gas emission for low-luminosity AGN and in (near-IR) molecular gas emission for higher-luminosity AGN. We have also observed gas rotating in the galaxy plane, sometimes in compact (few tens of pc) disks which may be fuelling the AGN. Outflows have been observed mostly in ionized gas emission from the narrow-line region, whose flux distributions and kinematics frequently correlate with radio flux distributions. Channel maps along the emission-line profiles reveal velocities as high as ~ 600 km/s. Mass outflow rates in ionized gas range from 0.01 to 0.001 solar masses per year and are 10-100 times larger than the mass accretion rates to the AGN, supporting an origin for the bulk of the outflow in gas from the galaxy plane entrained by a nuclear jet or accretion disk wind.
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).
