相关论文: Mapping the Dynamics of Cold Gas around Sgr A* thr…

New HI observations of the nearby radio-loud galaxies Centaurus A and B2 0258+35 show broad absorption (Delta_v=400km/s) against the unresolved nuclei. Both sources belong to the cases where blue- and redshifted absorption is observed at…

The clumpy maser disks observed in some galactic nuclei mark the outskirts of the accretion disk that fuels the central black hole and provide a potential site of nuclear star formation. Unfortunately, most of the gas in maser disks is…

A cold neutral and extremely dim accretion disk may be present as a remnant of a past vigorous activity around the black hole in our Galactic Center (GC). Here we discuss ways to detect such a disk through its interaction with numerous…

The recent identification of one or two sub-parsec disks of young, massive stars orbiting the ~4e6 solar mass black hole Sgr A* has prompted an "in-situ" scenario for star formation in disks of gas formed from a cloud captured from the…

Cold inactive disks are believed to exist in Low Luminosity AGN (LLAGN). They may also exist in the nuclei of inactive galaxies and in the center of our own Galaxy. These disks would then be embedded in the observed dense nuclear stellar…

Massive black holes surrounded by a gaseous disk have been a prevailing model to explain a wide spectrum of astrophysical phenomena related to active galactic nucle (AGNs). However, direct and precise measurements of the disk density…

Recent targeted studies of associated HI absorption in radio galaxies are starting to map out the location, and potential cosmological evolution, of the cold gas in the host galaxies of Active Galactic Nuclei (AGN). The observed 21 cm…

Active galaxies are thought to be both fueled and obscured by neutral gas removed from the host galaxy and funneled into a central accretion disk. We performed a VLA imaging survey of 21 cm absorption in Seyfert and starburst nuclei to…

This review summarizes recent studies of the cold neutral hydrogen gas associated with galaxies probed via the HI 21-cm absorption line. HI 21-cm absorption against background radio-loud quasars is a powerful tool to study the neutral gas…

We present Giant Metrewave Radio Telescope and Very Large Array observations of HI 21-cm absorption in ten z<=0.2 galaxy mergers that host strong radio sources. Seven of these mergers show strong absorption [with N(HI) ~10^{21-22} cm^{-2},…

Several examples of thin, Keplerian, sub-parsec megamaser disks have been discovered in the nuclei of active galaxies and used to precisely determine the mass of their host black holes. We show that there is an empirical linear correlation…

HI 21~cm absorption spectroscopy provides an excellent probe of the neutral gas content of absorbing galaxies, yielding information on their kinematics, mass, physical size and ISM conditions. The high sensitivity, unrivaled frequency…

Active galactic nuclei (AGN) are powered by the accretion of disks of gas onto supermassive black holes (SMBHs). Stars and stellar remnants orbiting the SMBH in the nuclear star cluster (NSC) will interact with the AGN disk. Orbiters…

The S0 galaxy NGC 3245 contains a circumnuclear disk of ionized gas and dust with a radius of 1.1" (110 pc), making it an ideal target for dynamical studies with the Hubble Space Telescope. We have obtained spectra of the nuclear disk with…

Cold, neutral interstellar gas, the reservoir for star formation, is traced through the absorption of the 21-centimetre continuum radiation by neutral hydrogen (HI). Although detected in one hundred cases in the host galaxies of distant…

We have conducted a search for optical circumstellar absorption lines in the spectra of 16 debris disc host stars. None of the stars in our sample showed signs of emission line activity in either H$_{\alpha}$, Ca II or Na I, confirming…

The Galactic center stellar disk and the circumnuclear ring provide a unique opportunity to study in detail the dynamics and physical conditions of distant molecular disks in the nuclei of galaxies. One of the key questions is how these…

This review summarises what we have learnt in the last two decades based on HI 21-cm absorption observations about the cold interstellar medium (ISM) in the central regions of active galaxies and the interplay between this gas and the…

The physical and kinematical conditions of the gas surrounding an active galactic nucleus (AGN) offer key diagnostics for understanding the processes occurring in the inner few kpc around the nucleus. Neutral hydrogen can give important…

Several thin, Keplerian, sub-parsec megamaser disks have been discovered in the nuclei of active galaxies and used to precisely determine the mass of their host black holes. We show that there is an empirical linear correlation between the…