Bibcode
Gallimore, J. F.; Baum, S. A.; Henkel, C.; Claussen, M.; Glass, I. S.; Prieto, M. A.
Referencia bibliográfica
American Astronomical Society, 195th AAS Meeting, #115.09; Bulletin of the American Astronomical Society, Vol. 31, p.1544
Fecha de publicación:
12
1999
Número de citas
0
Número de citas referidas
0
Descripción
The brighter water masers of NGC 1068 appear to trace molecular gas in a
parsec-scale disk surrounding the central engine. We find evidence that
these masers are reverberating in response to a central, common pump
source, presumably the central engine. Firstly, the luminosities of
individual maser features are correlated on time-scales as fine as
years, even though the dynamical time is 10000 years. Secondly, we have
detected a simultaneous flare event among blueshifted masers and
redshifted masers; the flare signal is symmetric in Doppler velocity
about the systemic velocity of the galaxy. Thirdly, we present a model
in which a 1988 X-ray flare of the central engine may have caused (1)
the loss of maser signal over the period 1990--1991, and (2) a
subsequent peak of emission from warm dust between 1994 and 1995.
Although the present data are not sufficient to pin down an accurate,
geometric distance measure, they favor a distance of 18 Mpc to NGC 1068.
We demonstrate how further monitoring may provide a more accurate
distance measurement.