Related papers: Ejection of Matter and Energy from NGC 4258
The recent observations of high-velocity maser emissions in NGC 4258 by Myoshi et al provide strong evidence for a central object of mass 3.6 10**7 solar masses in the nucleus of this galaxy based on a kinematic argument. However, they…
The sub-parsec masing disk recently found to be orbiting a central mass of $\sim3.6\times10^7$~\msun\ in the Seyfert/LINER galaxy NGC~4258 provides the most compelling evidence to date for the existence of a massive black hole in the…
There is now dynamical evidence for massive dark objects at the center of several galaxies, but suggestions that these are supermassive black holes are based only on indirect astrophysical arguments. The recent unprecedented measurement of…
We determine the mass of the black hole at the center of the spiral galaxy NGC 4258 by constructing axisymmetric dynamical models of the galaxy. These models are constrained by high spatial resolution imaging and long-slit spectroscopy of…
Naturally occurring water vapor maser emission at 1.35 cm wavelength provides an accurate probe for the study of accretion disks around highly compact objects, thought to be black holes, in the centers of active galaxies. Because of the…
The water maser in the mildly active nucleus in the nearby galaxy NGC4258 traces a thin, nearly edge-on, subparsec-scale Keplerian disk. Using the technique of very long baseline interferometry, we have detected the proper motions of these…
We report measurements of centripetal accelerations of maser spectral components of NGC 4258 for 51 epochs spanning 1994 to 2004. This is the second paper of a series, in which the goal is determination of a new geometric maser distance to…
NGC 4258 is an SABbc Seyfert galaxy, located at a distance of $7.2 \pm 0.3$ Mpc. This object is well known by its nearly edge-on molecular nuclear disc, located between 0.16 and 0.28 pc from the nucleus, whose H$_2$O maser emission allows a…
Supermassive black holes in the nuclei of active galaxies expel large amounts of matter through powerful winds of ionized gas. The archetypal active galaxy NGC 5548 has been studied for decades, and high-resolution X-ray and UV observations…
Water vapor emission at 22 GHz is reported from the nucleus of the LINER galaxy Mrk 1419 (NGC 2960). Single-dish spectra of the maser source show properties that are similar to those seen in NGC 4258, namely (1) a cluster of systemic H2O…
The nucleus of the Seyfert galaxy NGC 1068 is believed to host a supermassive black hole. Evidence for the presence of a massive central object is provided by water maser emission, which displays a linear pattern in the sky, suggestive of a…
Observations of line emission from water masers near the center of the galaxy NGC 4258 have recently provided compelling evidence for rotating disk of gas, viewed nearly edge-on, surrounding a massive black hole (Miyoshi etal. 1995). We…
For a few nearby active nuclei, the disc orbiting the black hole is traced by water maser emission. By combining a simple model together with observed velocity profiles, we show that it is possible to put constraints on the black hole mass…
H$_2$O MegaMaser emission may arise from thin gas discs surrounding the massive nuclei of galaxies such as NGC\,4258, but the physical conditions responsible for the amplified emission are unclear. A detailed view of these regions is…
We present a stellar dynamical mass measurement of the supermassive black hole in the elliptical (E1) galaxy NGC 3258. Our findings are based on integral field unit spectroscopy from the Multi Unit Spectroscopic Explorer (MUSE) observations…
We present HST/STIS spectra of the Sbc spiral galaxy NGC 4041 which were used to map the velocity field of the gas in its nuclear region. We detect the presence of a compact (r~0.4" ~40 pc), high surface brightness, rotating nuclear disk…
Luminous water maser emission in the 6_(16)-5_(23) line at 22 GHz has been detected from two dozen galaxies. In all cases the emission is confined to the nucleus and has been found only in AGN, in particular, in Type 2 Seyferts and LINERs.…
We aim to explore the relationship between globular cluster total number, $N_{\rm GC}$, and central black hole mass, $M_\bullet$, in spiral galaxies, and compare it with that recently reported for ellipticals. We present results for the Sbc…
The nuclear gas kinematics probed by water vapor maser emission has shown that two nearby active galaxies, NGC 1068 and NGC 4258, have a supermassive object in their nuclei and their masses are nearly comparable; a few 10^7 solar masses.…
Observational work conducted over the last few decades indicates that all massive galaxies have supermassive black holes at their centres. Although the luminosities and brightness fluctuations of quasars in the early Universe suggest that…