Bibcode
DOI
Marconi, Alessandro; Schreier, Ethan J.; Koekemoer, Anton; Capetti, Alessandro; Axon, David; Macchetto, Duccio; Caon, N.
Bibliographical reference
The Astrophysical Journal, Volume 528, Issue 1, pp. 276-291.
Advertised on:
1
2000
Journal
Citations
82
Refereed citations
73
Description
We report new Hubble Space Telescope WFPC2 and NICMOS observations of
the center of the nearest radio galaxy Centaurus A (NGC 5128) and
discuss their implications for our understanding of the active nucleus
and jet. We detect the active nucleus in the near-IR (K and H) and, for
the first time, in the optical (I and V), deriving the spectral energy
distribution of the nucleus from the radio to X-rays. The optical and
part of the near-IR emission can be explained by the extrapolation of
the X-ray power law reddened by AV~14, a value consistent
with other independent estimates. The 20 pc scale nuclear disk
discovered by Schreier and colleagues is detected in the [Fe II]
λ1.64 μm line and presents a morphology similar to that
observed in Paα with a [Fe II]/Paα ratio typical of
low-ionization Seyfert galaxies and LINERs. NICMOS 3 Paα
observations in a 50''x50'' circumnuclear region
suggest enhanced star formation (~0.3 Msolar yr-1)
at the edges of the putative bar seen with ISO, perhaps due to shocks
driven into the gas. The light profile, reconstructed from V, H, and K
observations, shows that Centaurus A has a core profile with a resolved
break at ~4" and suggests a black hole mass of ~109
Msolar. A linear blue structure aligned with the radio/X-ray
jet may indicate a channel of relatively low reddening in which dust has
been swept away by the jet.