Probing the obscuring medium around active nuclei using masers: The case of 3C403
arXiv:astro-ph/0408327 · doi:10.1007/s10509-005-3669-y
Abstract
We report the first detection of a water megamaser in a radio-loud galaxy, 3C403, and present a follow-up study using the VLA. 3C403 has been observed as a part of a small sample of FRII galaxies with evidence of nuclear obscuration. The isotropic luminosity of the maser is ~1200 solar luminosities. With a recessional velocity of cz~17680 km/s it is the most distant water maser so far reported. The line arises from the densest (> 10^(8) cm^(-3)) interstellar gas component ever observed in a radio-loud galaxy. Two spectral features are identified, likely bracketing the systemic velocity of the galaxy. Our interferometric data clearly indicate that these arise from a location within 0.1" (~110 pc) from the active galactic nucleus. We conclude that the maser spots are most likely associated with the tangentially seen parts of a nuclear accretion disk, while an association with dense warm gas interacting with the radio jets cannot yet be ruled out entirely.
arXiv commentSeven pages. Three figures. To appear in the Proceedings of the 2004 European Workshop: "Dense Molecular Gas around Protostars and in Galactic Nuclei", Eds. Y. Hagiwara, W.A. Baan, H.J. van Langevelde, 2004, a special issue of ApSS, Kluwer
References in corpus (7)
- Unified Schemes for Radio-Loud Active Galactic Nuclei
- The Nature of the Nuclear H2O Masers of NGC 1068: Reverberation and Evidence for a Rotating Disk Geometry
- HI absorption in radio galaxies: effect of orientation or interstellar medium?
- The Flaring H2O Megamaser and Compact Radio Source in Mrk 348
- Understanding the nature of FRII optical nuclei: a new diagnostic plane for radio galaxies
- Molecular Gas in 3C 293: The First Detection of CO Emission and Absorption in an F-R II Radio Galaxy
- Molecular hydrogen emission in Cygnus A