相关论文: The Radio Jets and Accretion Disk in NGC 4261

The physical conditions in the inner parsec of accretion disks believed to orbit the central black holes in active galactic nuclei can be probed by imaging the absorption (by ionized gas in the disk) of background emission from a radio…

We observed the nuclear region of NGC 4261 (3C270) with the VLBA at two frequencies (1.6 and 8.4 GHz) simultaneously. We find that the position angle of the parsec-scale radio axis agrees, within the errors, with the position angle of the…

NGC 4261 (3C 270) is a low-luminosity radio galaxy with two symmetric kiloparsec-scale jets. Earlier Hubble Space Telescope observations indicated the presence of a hundred-parsec scale disk of cool dust and gas surrounding a central,…

The physical conditions in the inner parsec of accretion disks believed to orbit the central black holes in active galactic nuclei can be probed by imaging the absorption of background radio emission by ionized gas in the disk. We report…

We report multifrequency phase-referenced observations of the nearby radio galaxy NGC 4261, which has prominent two-sided jets, using the Very Long Baseline Array at 1.4-43 GHz. We measured radio core positions showing observing frequency…

The cold molecular gas in the circumnuclear disk (CND) of radio galaxies provides critical information for understanding the mass accretion onto active galactic nuclei. We present the first detection and maps of HCN J=1-0 and HCO+ J=1-0…

We consider the implications of recent infrared and radio observations of the nucleus of NGC 4258. There is no direct evidence that the nucleus has been steadily accreting on the viscous timescale of the outer masing disk, which is >~ 10^9…

Using observations from the Chandra and XMM-Newton X-ray observatories, we examine the interaction between the intra-group medium and central radio source in the nearby NGC 4261 galaxy group. We confirm the presence of cavities associated…

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…

We report on the X-ray properties of the radio galaxy NGC 4261, combining information from the XMM, Chandra, and SAX satellites. Goals of this study are to investigate the origin of the X-rays from this low-power radio galaxy and the nature…

We study a sample of 44 low-luminosity radio-loud AGN, which represent a range of nuclear radio-power spanning 5 orders of magnitude, to unveil the accretion mechanism in these galaxies. We estimate the accretion rate of gas associated with…

We review the latest attempts to determine the accretion geometry in radio-loud active galactic nuclei (AGN). These objects, which comprise ~10-20% of the AGN population, produce powerful collimated radio jets that can extend thousands of…

We have used the VLBA to produce a high dynamic range image of the nucleus of NGC 6251 at 1.6 GHz and snapshot images at 5.0, 8.4, and 15.3 GHz to search for emission from a parsec-scale counterjet. Previous VLBI images at 1.6 GHz have set…

It seems to be a widely accepted opinion that the types of accretion disks (or flows) generally realized in the nuclei of radio galaxies and in further lower mass-accretion rate nuclei are inner, hot, optically thin, radiatively inefficient…

VLBA high spatial resolution observations of the disk structure of the active galactic nucleus NGC 1068 has recently revealed that the kinematics and geometry of this AGN is well characterized by an outer disk of H2O maser emission having a…

The innermost regions of Active Galactic Nuclei (AGN) are critical for understanding galaxy evolution and the dynamics of matter near a Supermassive Black Hole (SMBH). Yet, due to smaller angular projections, it is very difficult to resolve…

We report on the results of a simultaneous monitoring campaign employing eight Chandra X-ray (0.5-10 keV) and six VLA/EVLA (8.4 GHz) radio observations of NGC 4051 over seven months. Evidence for compact jets is observed in the 8.4 GHz…

NGC4261 (3C270) is an elliptical galaxy containing a 300-parsec scale nuclear disk of gas and dust imaged by the Hubble Space Telescope (HST), around a central supermassive black hole. Previous VLBI observations of NGC4261 revealed a gap in…

We present an archival analysis of Chandra X-ray observations for twelve nearby early-type galaxies hosting radio sources with radio power $>10^{23} \, \rm{W}~\rm{Hz}^{-1}$ at 1.4 GHz, similar to the radio power of the radio source in NGC…

We present an analysis of polarimetric observations at 22 GHz of the water vapor masers in NGC 4258 obtained with the VLA and the GBT. We do not detect any circular polarization in the spectrum indicative of Zeeman-induced splitting of the…