Related papers: Theory and Extragalactic Masers
We present observations of the 22 GHz water megamasers in the circumnuclear disk of NGC 3079 obtained with the Green Bank Telescope. The data are analyzed for circular polarization due to the Zeeman-induced splitting of the water maser…
NGC7538 IRS1 is considered the best high-mass accretion disk candidate around an O-type young star in the northern hemisphere. We investigated the 3D kinematics and dynamics of circumstellar gas with very high linear resolution, from tens…
In this article we examine the hypothesis that the highest energy cosmic rays are complex nuclei from extragalactic sources. Under reasonable physical assumptions, we show that the nearby metally rich starburst galaxies (M82 and NGC 253)…
We illustrate a novel signature of black hole binaries from their effect on the kinematics of water maser emission in their environments. With the help of simulations, we establish the condition for clumps to mase based on their coherence…
We present high resolution (sub-mas) VLBI maps of nuclear H2O megamasers for seven galaxies. In UGC6093, the well-aligned systemic masers and high-velocity masers originate in an edge-on, flat disk and we determine the mass of the central…
NGC7538 is a complex massive star-forming region. The region is composed of several radio continuum sources, one of which is IRS1, a high-mass protostar, from which a 0.3 pc molecular bipolar outflow was detected. Several maser species have…
We report the detection of 22 GHz water vapor emission toward the starburst galaxy NGC2146, made using the Effelsberg 100-m telescope. Interferometric observations with the Very Large Array (VLA) show that a part of the emission originates…
22 GHz water vapor emission was observed toward the central region of the spiral starburst galaxy NGC 253. Monitoring observations with the 100-m telescope at Effelsberg and measurements with the BnC array of the VLA reveal three distinct…
Using the Green Bank Telescope, we conducted a ``snapshot'' survey for water maser emission toward the nuclei of 611 galaxies and detected eight new sources. The sample consisted of nearby (v < 5000 km/s) and luminous (M_B < -19.5)…
We report four new 22 GHz water masers found in a Green Bank Telescope search toward 37 nearby objects. Our goal was to find new maser galaxies, AGN disk-masers, and objects where both hydroxyl and water maser species coexist. We observed…
A strong nuclear kilomaser, W1, has been found in the nearby galaxy NGC 253, associated with a forming super star cluster. Kilomasers could arise from the accretion disc around supermassive stars (>10^3 Msun), hypothetical objects that have…
We performed VLA observations of the 22 GHz H2O maser emission in the merging galaxy NGC6240, which hosts the well-known double active nuclei. In a previous paper, we reported on the first solid detection of the H2O maser emission in 2001.…
Multi-epoch VLBA observations of the maser in NGC 4258 have yielded a 4% geometrical distance to the galaxy. The potential scientific payoffs of finding similar objects at large distances, in the Hubble flow, are considerable. In this…
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.…
The standard unified scheme of active galactic nuclei requires the presence of high column densities of gas and dust potentially obscuring the central engine. So far, few direct subarcsecond resolution studies of this material have been…
We show that in many methanol maser sources the masers are located in lines, with a velocity gradient along them which suggests that the masers are situated in edge-on circumstellar, or protoplanetary, disks. We present VLBI observations of…
Despite theoretical predictions of the existence of many submillimeter masers, and some pioneering observational discoveries over the past few decades, these lines have remained relatively unstudied due to (i) challenges associated with…
OH(1720 MHz) and methanol masers are now recognized to be excellent probes of the interactions of supernova remnants with molecular clouds and tracers of massive star formation, respectively. To better understand the nature of star…
We have used the Australia Telescope Compact Array (ATCA) to make new observations of the 36.2-GHz ($4_{-1}\rightarrow3_0$E) methanol transition toward NGC 4945 and NGC 253. These observations have revealed the presence of new maser…
We have searched for 22 GHz H2O and 43/86/129 GHz SiO masers in bright IRAS point sources in the SMC and LMC, to test whether the kinematics of the mass loss from these stars depends on metallicity. H2O masers were detected in the red…