Water Maser Emission and the Parsec‐Scale Jet in NGC 3079

Abstract

We have conducted VLBI observations at subparsec resolution of water maser and radio continuum emission in the nucleus of the nearby active galaxy NGC 3079. The 22 GHz maser emission arises in compact (D0.01 pc at a distance of 16 Mpc) clumps, distributed over D2 pc along an axis that is approximately aligned with the major axis of the galactic disk. The Doppler velocities of the water maser clumps are consistent with their lying in the inner parsec of a molecular disk with a binding mass D106 rotating in the same sense as the edge-on kiloparsec-scale molecular disk observed in CO emission. M _ , However, the velocity Ðeld has a signiÐcant nonrotational component, which may indicate supersonic turbulence in the disk. This distribution is markedly di †erent from that of water masers in NGC 4258, which trace a nearly perfectly Keplerian rotating disk with a binding mass of 3.5 ] 107The 22 M _ . GHz radio continuum emission in NGC 3079 is dominated by a compact (\0.1 pc) source that is o †set 0.5 pc to the west of the brightest maser feature. No bright maser emission is coincident with a detected compact continuum source. This suggests that the large apparent luminosity of the maser is not caused by beamed ampliÐcation of high brightness temperature continuum emission. At 8 and 5 GHz, we conÐrm the presence of two compact continuum sources with a projected separation of 1.5 pc. Both have inverted spectra between 5 and 8 GHz and steep spectra between 8 and 22 GHz. NGC 3079 may be a nearby, low-luminosity example of the class of compact symmetric gigahertz-peaked spectrum radio sources. We detected a third continuum component that lies along the same axis as the other two, strongly suggesting that this galaxy possesses a nuclear jet. Faint maser emission was detected near this axis, which may indicate a second population of masers associated with the jet.

Mid-infrared imaging- and spectro-polarimetric subarcsecond observations of NGC 1068

“…Although misaligned structures on similar spatial scales have been observed in other AGNs (i.e. Miyoshi et al 1995;Wilson et al 1995;Greenhill et al 1997;Hagiwara et al 1997;Trotter et al 1998), it is not the scope of this paper to investigate these, and we refer to the reader to the discussion in Lawrence & Elvis (2010).…”

Observational evidence for massive black holes in the centers of active galaxies

“…The properties of these masers are listed in Table 3. Unfortunately, none Trotter et al 1998, Satoh et al 1998 D = distance, v 0 = systemic velocity, ∆v = velocity range, ∆R = linear extent, v φ = rotational velocity, R i /R o = inner/outer radius of disk, M = central mass, ρ = central mass density, L x = X-ray luminosity.…”

Disks, tori, and cocoons: emission and absorption diagnostics of AGN environments

“…1). Maps of maser emission in NGC 3079 (Trotter et al 1998 In the firmly established cases, NGC 4258, NGC 1068, and Circinus, maser emission traces well ordered disk material at radii of 0.1-1 pc and rotation speeds up to ∼ 1100 km s −1 around central engines of 10 6 -10 8 M ⊙ . Disk shape, orientation with respect to the line of sight, velocity shear, and background amplification largely determine where favoured maser gain paths are found within the disks (i.e., chiefly where the orbital motion is nearly parallel or perpendicular to the line of sight).…”