Article

The Warped Disk of Centaurus A from a radius of 2 to 6500 pc

Publications of the Astronomical Society of Australia (Impact Factor: 3.12). 12/2009; DOI: 10.1071/AS09069
Source: arXiv

ABSTRACT We compile position and inclination angles for tilted ring fits to the warped dusty and gaseous disk spanning radius 1.8 to 6500 pc from recent observations. For radii exterior to a kpc, tilted ring orientations lie on an arc on a polar inclination versus position angle plot, suggesting that precession following a merger can account for the ring morphology. Three kinks in the ring orientations are seen on the polar plot, the one at radius of about 1.3 kpc we suspect corresponds to the location where self-gravity in the disk affects the ring precession rate. Another at a radius of about 600 pc may be associated with a gap in the gas distribution. A third kink is seen at a radius of 100 pc. A constant inclination tilted disk precessing about the jet axis may describe the disk between 100 and 20 pc but not interior to this. A model with disk orientation matching the molecular circumnuclear disk at 100 pc that decays at smaller radii to an inner flat disk perpendicular to the jet may account for disk orientations within 100 pc. Neither model would account for the cusps or changes in disk orientation at 100 or 600 pc. Comment: accepted PASA

0 Bookmarks
 · 
65 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The prominent radio galaxy Centaurus A is the closest active galaxy and a prime opportunity to study the central supermassive black hole and its influence on the environment in great detail. We used the near-infrared integral field spectrograph SINFONI to measure Centaurus A's black hole mass from both stellar and gas kinematics. This study shows how the advance in observing techniques and instrumentation drive the field of black hole mass measurements, and concludes that adaptive optics assisted integral field spectroscopy is the key to identifying the effects of the active galactic nucleus on the surrounding ionised gas. The best-fit black hole mass is MBH = 4.5 (+1.7, -1.0) × 107 MSun (from H2 kinematics) and MBH = 5.5 ± 3.0 × 107 MSun (from stellar kinematics; both with 3σ errors). This is one of the cleanest gas versus star comparisons of a black hole mass determination, and brings Centaurus A into agreement with the relation of black hole mass versus galaxy stellar velocity dispersion.
    03/2010;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report the existence of spiral arms in the recently formed gaseous and dusty disk of the closest giant elliptical, NGC 5128 (Centaurus A), using high resolution 12CO(2-1) observations of the central 3 arcmin (3 kpc) obtained with the Submillimeter Array (SMA). This provides evidence that spiral-like features can develop within ellipticals if enough cold gas exists. We elucidate the distribution and kinematics of the molecular gas in this region with a resolution of 4.4 x 1.9 (80 pc x 40 pc). The spiral arms extend from the circumnuclear gas at a radius of 200 pc to at least 1 kiloparsec. The general properties of the arms are similar to those in spiral galaxies: they are trailing, the width is \sim 500 \pm 200 pc, and the pitch angle is 20 degrees. From independent estimates of the time when the HI-rich galaxy merger occurred, we infer that the formation of spiral arms happened on a time scale of less than \sim10^8 yr. The formation of spiral arms increases the gas density and thus the star formation efficiency in the early stages of the formation of a disk.
    The Astrophysical Journal Letters 08/2012; 756(1). · 6.35 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The diffuse neutrino flux from FRI and BL Lac type galaxies generated from interactions of their own gamma radiation with the gas and dust at the sources is reported. This neutrino-production channel has not been studied in detail up to now. The calculations are based on individual estimations of the neutrino flux in two nearby AGN's: Centaurus A and M87, assuming the validity of the AGN unification model. The predictions for Centaurus A and M87 involved the parameterization of the measured gamma-ray luminosities and the modeling of the material of the galaxies both based on observations performed by several detectors. No hadronic origin for the TeV photons is assumed. The results show that, although the corresponding neutrino flux ($E^{2} \Phi_{\nu + \bar{\nu}} < 10^{-13} s^{-1} sr^{-1} GeV cm^{-2}$) is not competitive at high-energies ($E_\nu > 1 TeV$) with that from hadronic models, FRI and BL Lac galaxies with gamma emission should be already contributing to the diffuse flux of neutrinos in the universe.
    Astroparticle Physics 09/2013; 37. · 4.78 Impact Factor

Full-text (2 Sources)

View
50 Downloads
Available from
May 20, 2014