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Modelling the ENLR in NGC1068  [PDF]
L. S. Nazarova,P. T. O'Brien,M. J. Ward,P. M. Gondhalekar
Physics , 1997,
Abstract: We present photoionization models of the high excitation gas in the Extended Narrow Line Region (ENLR) of NGC1068. The ENLR line fluxes have been calculated allowing for attenuation of the central-source ionizing continuum as a function of distance from the centre. Diffuse continuum emission from low density ENLR gas is included as an important secondary source of ionization. The observed high excitation emission further than 25 arcsec from the centre of NGC1068 can be fitted by photoionization models using a central-source luminosity of 3.6x10^44 erg/s between 10^14.6 and 10^18.4 Hz, with the continuum shape attenuated by nuclear gas with an integrated column density of N_h=10^22 cm^-2. The reflected soft X-ray continuum from the attenuating gas could be responsible for about 10% of the observed, resolved circumnuclear soft X-ray continuum extending out to 15 arcsec from the centre (Wilson et al 1992).
Why Does NGC 1068 Have a More Powerful Active Galactic Nucleus than NGC 4258 ?  [PDF]
Takashi Murayama,Yoshiaki Taniguchi
Physics , 1997, DOI: 10.1093/pasj/49.4.L13
Abstract: The nuclear gas kinematics probed by water vapor maser emission has shown that two nearby active galaxies, NGC 1068 and NGC 4258, have a supermassive object in their nuclei and their masses are nearly comparable; a few 10^7 solar masses. Nevertheless, the activity of the central engine of NGC 1068 is more powerful by two orders of magnitude than that of NGC 4258. Since it is generally considered that the huge luminosities of active galactic nuclei are attributed to the mass accretion onto a supermassive black hole, the above observational results suggest that the accretion rate in NGC 1068 is much higher than that in NGC 4258. Comparing the kinematical properties of the accreting molecular clouds between NGC 1068 and NGC 4258, we find possible evidence for dynamical gas accretion in NGC 1068, which may be responsible for the more powerful central engine in this galaxy.
Kinematics of Molecular Gas in the Nucleus of NGC1068, from H2 line emission observed with VLT  [PDF]
D. Alloin,E. Galliano,J. G. Cuby,O. Marco,D. Rouan,Y. Clenet,G. L. Granato,A. Franceschini
Physics , 2001, DOI: 10.1051/0004-6361:20010250
Abstract: We present results about the distribution and kinematics of the molecular environment of the AGN in NGC1068, over a 1.5'' x 3.5'' region around the central engine in NGC1068, derived from H2 line emission detected with ISAAC at VLT/ANTU on ESO/Paranal. The H2 emitting molecular gas is found to be distributed along the East-West direction and with two main peak emission (knots) located at a distance of about 70 pc from the central engine. The eastern H2 knot is more intense than the western one. The line profiles mapped across the entire 1.5'' x 3.5'' region, at a spatial resolution of 0.3'' x 0.45'', appear to be quite complex with either a blue or red wing. At first order, we find a velocity difference of 140 km/s between the two knots; if interpreted as quasi-keplerian velocity, this implies a central enclosed mass of 10^8 solar masses.
Modelling gaseous and stellar kinematics in the disc galaxies NGC 772, NGC 3898, and NGC 7782  [PDF]
E. Pignatelli,E. M. Corsini,J. C. Vega Beltran,C. Scarlata,A. Pizzella,J. G. Funes,S. J.,W. W. Zeilinger,J. E. Beckman,F. Bertola
Physics , 2000, DOI: 10.1046/j.1365-8711.2001.04207.x
Abstract: We present V-band surface photometry and major-axis kinematics of stars and ionized gas of three early-type spiral galaxies, namely NGC 772, NGC 3898 and NGC 7782. For each galaxy we present a self-consistent Jeans model for the stellar kinematics, adopting the light distribution of bulge and disc derived by means of a two-dimensional parametric photometric decomposition. This allowed us to investigate the presence of non-circular gas motions, and derive the mass distribution of luminous and dark matter in these objects. NGC 772 and NGC 7782 have apparently normal kinematics with the ionized gas tracing the gravitational equilibrium circular speed. This is not true in the innermost region (r < 8'') of NGC 3898 where the ionized gas is rotating more slowly than the circular velocity predicted by dynamical modelling. This phenomenon is common in the bulge-dominated galaxies for which dynamical modelling enables us to make the direct comparison between the gas velocity and the circular speed, and it poses questions about the reliability of galaxy mass distributions derived by the direct decomposition of the observed ionized-gas rotation curve into the contributions of luminous and dark matter.
Modeling the [Fe II]λ1.644μm outflow and comparison with H$_2$ and H$^+$ kinematics in the inner 200 pc of NGC 1068  [PDF]
F. K. B. Barbosa,T. Storchi-Bergmann,P. McGregor,T. B. Vale
Physics , 2014, DOI: 10.1093/mnras/stu1637
Abstract: We map the kinematics of the inner (200 pc) narrow-line region (NLR) of the Seyfert 2 galaxy NGC 1068 using the instrument NIFS and adaptative optics at the Gemini North Telescope. Channel maps and position-velocity diagrams are presented at a spatial resolution of $\sim$ 10 pc and spectral resolution $\sim$ 5300 in the emission lines [Fe II] {\lambda} 1.644 {\mu}m, H$_2$ {\lambda} 2.122 {\mu}m and Br{\gamma}. The [Fe II] emission line provides a better coverage of the NLR outflow than the previously used [O III] {\lambda} 5007 emission line, extending beyond the area of the bi-polar cone observed in Br{\gamma} and [O III]. This is mainly due to the contribution of the redshifted channels to the NE of the nucleus, supporting its origin in a partial ionized zone with additional contribution from shocks of the outflowing gas with the galactic disc. We modeled the kinematics and geometry of the [Fe II] emitting gas finding good agreement with the data for outflow models with conical and lemniscate (or hourglass) geometry. We calculate a mass outflow rate $1.9^{+1.9}_{-0.7}$ M$_{\odot}~$yr$^{-1}$ but a power for the outflow of only 0.08% L$_{Bol}$. The molecular (H$_2$) gas kinematics is completely distinct from that of [Fe II] and Br{\gamma}, showing radial expansion in an off-centered $\sim$ 100 pc radius ring in the galaxy plane. The expansion velocity decelerates from $\sim$ 200 km/s in the inner border of the ring to approximately zero at the outer border where our previous studies found a 10 Myr stellar population.
Resolved Spectroscopy of the Narrow-Line Region in NGC 1068: Kinematics of the Ionized Gas  [PDF]
D. M. Crenshaw,S. B. Kraemer
Physics , 2000, DOI: 10.1086/312581
Abstract: We have determined the radial velocities of the [O III] emitting gas in the inner narrow-line region (NLR) of the Seyfert 2 galaxy NGC 1068, along a slit at position angle of 202 degrees, from STIS observations at a spatial resolution of 0.1 arcsec and a spectral resolving power of approximately 1000. We use these data to investigate the kinematics of the NLR within 6 arcsec (430 pc) of the nucleus. The emission-line knots show evidence for radial acceleration, to a projected angular distance of 1.7 arcsec in most cases, followed by deceleration that approaches the systemic velocity at a projected distance of about 4 arcsec. We find that a simple kinematic model of biconical radial outflow can match the general trend of observed radial velocities. In this model, the emitting material is evacuated along the bicone axis, and the axis is inclined 5 degrees out of the plane of the sky. The acceleration of the emission-line clouds provides support for dynamical models that invoke radiation and/or wind pressure. We suggest that the deceleration of the clouds is due to their collision with a patchy and anistropically distributed ambient medium.
2D mapping of young stars in the inner 180 pc of NGC 1068: correlation with molecular gas ring and stellar kinematics  [PDF]
Thaisa Storchi-Bergmann,Rogemar A. Riffel,Rogerio Riffel,Marlon R. Diniz,Tiberio Borges Vale,Peter J. McGregor
Physics , 2012, DOI: 10.1088/0004-637X/755/2/87
Abstract: We report the first two-dimensional mapping of the stellar population and non-stellar continua within the inner 180 pc (radius) of NGC 1068 at a spatial resolution of 8 pc, using integral field spectroscopy in the near-infrared. We have applied the technique of spectral synthesis to data obtained with the instrument NIFS and the adaptive optics module ALTAIR at the Gemini North Telescope. Two episodes of recent star formation are found to dominate the stellar population contribution: the first occurred 300 Myr ago, extending over most of the nuclear region; the second occurred just 30 Myr ago, in a ring-like structure at ~100 pc from the nucleus, where it is coincident with an expanding ring of H2 emission. Inside the ring, where a decrease in the stellar velocity dispersion is observed, the stellar population is dominated by the 300 Myr age component. In the inner 35 pc, the oldest age component (age > 2Gyr) dominates the mass, while the flux is dominated by black-body components with temperatures in the range 700 < T < 800 K which we attribute to the dusty torus. We also find some contribution from black-body and power-law components beyond the nucleus which we attribute to dust emission and scattered light.
Gas Kinematics and the Black Hole Mass at the Center of the Radio Galaxy NGC 4335  [PDF]
Gijs Verdoes Kleijn,Roeland van der Marel,Tim de Zeeuw,Jacob Noel-Storr,Stefi Baum
Physics , 2002, DOI: 10.1086/344073
Abstract: (abridged) We investigate the kinematics of the central gas disk of the radio-loud elliptical galaxy NGC 4335, derived from HST/STIS long-slit spectroscopic observations of Halpha+[NII] along 3 parallel slit positions. The observed mean velocities are consistent with a rotating thin disk. We model the gas disk in the customary way. This sets a 3 sigma upper limit of 10^8 Msun on black hole mass, Mbh. The velocity dispersion at r <0.5'' is in excess of that predicted by the thin rotating disk model. This does not invalidate the model, if the excess dispersion is caused by localized turbulent motion in addition to bulk circular rotation. However, if instead the dispersion is caused by the BH potential then a mass Mbh ~ 6x10^8 Msun is inferred by modeling the central gas dispersion as due to an isotropic spherical distribution of collisionless gas cloudlets. The stellar kinematics for NGC 4335 are derived from a ground-based (WHT/ISIS) long-slit observation along the galaxy major axis. A two-integral model of the stellar dynamics yields Mbh >= 3x10^9 Msun. However, there is reason to believe that this model overestimates Mbh. Reported correlations between black hole mass and inner stellar velocity dispersion sigma predict Mbh to be >= 5.4x10^8 Msun in NGC 4335. If our standard thin disk modeling of the gas kinematics is valid, then NGC 4335 has an unusually low Mbh for its velocity dispersion. If, on the other hand, this approach is flawed, and provides an underestimate of Mbh, then black hole masses for other galaxies derived from HST gas kinematics with the same assumptions should be treated with caution.
Mass distribution and kinematics of the barred galaxy NGC2336  [PDF]
K. Wilke,C. Moellenhoff,M. Matthias
Physics , 1999, DOI: 10.1023/A:1017554800715
Abstract: For the intermediate-type barred galaxy NGC2336 stationary models are constructed which reproduce in a consistent manner the observed distribution of the luminous matter and the observed gas kinematics in those regions affected by the bar. We present 2D fits to the observed NIR-band luminosity distribution that consist of three components: a bulge, a bar, and a disk. The brightness distribution of each component is converted into an underlying mass distribution by means of a suitable M/L-conversion. The resulting coadded potential of NGC2336 is implemented into a numerical code for the computation of closed orbits for gas clouds (HII-gas). Using the resulting tracks, the phase space accessible to the models is examined with regard to the main orbit families. For different orbit energies complete sets of closed orbits are computed. By projection to the reference frame of the galaxy, artificial rotation curves for every model are obtained and are compared with the observed rotation curves of the HII-gas. In an iterative procedure, the parameters of the NGC2336-models are optimized by computing and evaluating a large number of parameters. The result is a final model that reproduces the morphological structure of NGC2336 as well as the observed kinematics of the HII-gas. The parameter values from the morphological decomposition and those needed to fit the HII-rotation curves best are in exellent agreement. The effects of changing single parameter values and possible error sources are discussed in detail. It turns out that the kinematics of the warm HII-gas of NGC2336 can be explained without considering hydrodynamic effects, even in the central regions.
Molecular line emission in NGC1068 imaged with ALMA. I An AGN-driven outflow in the dense molecular gas  [PDF]
S. Garcia-Burillo,F. Combes,A. Usero,S. Aalto,M. Krips,S. Viti,A. Alonso-Herrero,L. K. Hunt,E. Schinnerer,A. J. Baker,F. Boone V. Casasola,L. Colina,F. Costagliola,A. Eckart,A. Fuente,C. Henkel,A. Labiano,S. Martin,I. Marquez,S. Muller,P. Planesas,C. Ramos Almeida,M. Spaans,L. J. Tacconi,P. P. van der Werf
Physics , 2014, DOI: 10.1051/0004-6361/201423843
Abstract: We investigate the fueling and the feedback of star formation and nuclear activity in NGC1068, a nearby (D=14Mpc) Seyfert 2 barred galaxy, by analyzing the distribution and kinematics of the molecular gas in the disk. We have used ALMA to map the emission of a set of dense molecular gas tracers (CO(3-2), CO(6-5), HCN(4-3), HCO+(4-3) and CS(7-6)) and their underlying continuum emission in the central r ~ 2kpc of NGC1068 with spatial resolutions ~ 0.3"-0.5" (~ 20-35pc). Molecular line and dust continuum emissions are detected from a r ~ 200pc off-centered circumnuclear disk (CND), from the 2.6kpc-diameter bar region, and from the r ~ 1.3kpc starburst (SB) ring. Most of the emission in HCO+, HCN and CS stems from the CND. Molecular line ratios show dramatic order-of-magnitude changes inside the CND that are correlated with the UV/X-ray illumination by the AGN, betraying ongoing feedback. The gas kinematics from r ~ 50pc out to r ~ 400pc reveal a massive (M_mol ~ 2.7 (+0.9, -1.2) x 10^7 Msun) outflow in all molecular tracers. The tight correlation between the ionized gas outflow, the radio jet and the occurrence of outward motions in the disk suggests that the outflow is AGN-driven. The outflow rate estimated in the CND, dM/dt ~ 63 (+21, -37) Msun yr^-1, is an order of magnitude higher than the star formation rate at these radii, confirming that the outflow is AGN-driven. The power of the AGN is able to account for the estimated momentum and kinetic luminosity of the outflow. The CND mass load rate of the CND outflow implies a very short gas depletion time scale of <=1 Myr.
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