相关论文: The millimeter-wave continuum spectrum of Centauru…
We describe results from our initial study of the diffuse X-ray emission structures in NGC 5128 (Cen A) using the Chandra X-ray Observatory observations. The high-angular resolution Chandra images reveal multi-scale X-ray struct ures with…
An analysis of the X-ray variability of the low luminosity Seyfert nucleus NGC 4395, based on a long XMM-Newton observation, is presented. The power spectrum shows a clear break from a flat spectrum (alpha ~ 1) to a steeper spectrum (alpha…
EGRET has detected 67 sources associated with active galactic nuclei. With the exception of radio galaxy Cen A, all are classified as belonging to the blazar class of active galactic nuclei. The cumulative exposure from multiple EGRET…
We report here multi-epoch, multi-frequency observations of the circular polarization in Sagittarius A*, the compact radio source in the Galactic Center. Data taken from the VLA archive indicate that the fractional circular polarization at…
We demonstrate that there is only one physical process required to explain the spectrum and the variability of the radio source at the dynamical center of our Galaxy, Sgr A*, in the frequency range from $\approx$1 to $\approx$1000 GHz,…
The Faint Object Spectrograph on the Hubble Space Telescope was used to obtain spectra of the central region of M87. These spectra cover the wavelength range 1140 - 1606 Angstrom and have a resolution of about 1 Angstrom. The nuclear…
Low dispersion spectra have been obtained of five planetary nebulae in the elliptical galaxy NGC 5128 (Centaurus-A) from the catalogue of Hui et al. (1993). The planetary nebulae (PN) cover a range of galactocentric radius from 7.9 to 17.7…
A key characteristic of many active galactic nuclei (AGN) is their variability, but its origin is poorly understood, especially in the radio domain. Williams et al. (2017) reported a ~50 per cent increase in peak flux density of the AGN in…
The origin of radio emission in radio-quiet (RQ) AGN remains a long-standing mystery. We present a detailed study of the cm to sub-mm emission from the nucleus of the nearby prototypical RQ Seyfert 2 galaxy, NGC 1068. We analyse…
As a prerequisite for interpreting new observations of the most distant radio galaxies, we make an optical study of the closest powerful radio source, Cygnus A. Using Keck imaging- and spectro-polarimetry in conjunction with HST, WFPC2…
Long-term measurements of the radio flux density of Cassiopeia A relative to Cygnus A have been carried out at 927 and 151.5 MHz. It was found the following mean secular decrease rates of the radio emission of Cassiopeia A: $(0.72\pm 0.03)%…
We present a Chandra ACIS-S observation of the nuclear region of the nearby spiral galaxy M51 (NGC 5194), which has a low-luminosity Seyfert 2 nucleus. The X-ray image shows the nucleus, southern extranuclear cloud, and northern loop, the…
PKS J2310-437 is an AGN with bright X-ray emission relative to its weak radio emission and optical continuum. It is believed that its jet lies far enough from the line of sight that it is not highly relativistically beamed. It thus provides…
The Seyfert galaxy NGC 985 is known to show a high-frequency excess in its radio continuum spectrum in a milli-Jansky level on the basis of previous observations at 1.4--15 GHz; a steep spectrum at low frequencies (a spectral index of…
We present radio and optical imaging and kinematic data for the radio galaxy Pictor A, including HST continuum and [OIII], emission-line images (at a resolution of 25 - 100 mas) and ground-based imaging and spectroscopy (at a resolution of…
We present results from two {\em Chandra}/ACIS-I observations and one {\em XMM-Newton} observation of X-ray emission from the ISM and the inner radio lobes of the nearby radio galaxy Centaurus A. The ISM has an average radial surface…
New observations of Sgr A have been carried out with the VLA using the broadband (2 GHz) continuum mode at 5.5 GHz, covering the central 30 pc region of the RBZ at the Galactic center. Using the MS-MFS algorithms in CASA, we have imaged Sgr…
We conducted a $369\;{\rm ks}$ NuSTAR observation on the X-ray pulsar Centaurus X-3, which covered two consecutive orbital cycles of the source, including two eclipse durations. We investigated the orbital-phase spectral variability over…
Recent observations of the microwave sky, by the space telescopes such as WMAP and Planck, have opened a new window into the analysis of continuum emission from supernova remnants (SNRs). In this paper, different emission models that can…
We examine deep Chandra X-ray observations of the Centaurus cluster of galaxies, Abell 3526. Applying a gradient magnitude filter reveals a wealth of structure, from filamentary soft emission on 100pc (0.5 arcsec) scales close to the…