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One of the most important problems in the study of AGN is understanding the detailed geometry, physics, and evolution of the central engines and their environments. The leading models involve an accretion disk and torus around a central…

天体物理学 · 物理学 2007-05-23 A. B. Peck , G. B. Taylor

We report the discovery of a new 21-cm HI absorption system using commissioning data from the Boolardy Engineering Test Array of the Australian Square Kilometre Array Pathfinder (ASKAP). Using the 711.5 - 1015.5 MHz band of ASKAP we were…

Arcminute-resolution radio continuum images at 408 and 1420 MHz from the Canadian Galactic Plane Survey (CGPS) have been used to reexamine radio sources listed in the Kallas and Reich (1980) catalogue. This catalogue is of particular…

天体物理学 · 物理学 2009-06-23 C. R. Kerton

From medium-resolution radio images, DR 16 was suspected to be a large cometary nebula. To test this suggestion we obtained a higher resolution (15\arcsec) VLA continuum map. We also analyzed data from the Canadian Galactic Plane Survey in…

天体物理学 · 物理学 2009-11-10 Otto P. Behre , Heinrich J. Wendker , Lloyd A. Higgs , Thomas L. Landecker

Transient astronomical sources are typically powered by compact objects and usually signify highly explosive or dynamic events. While radio astronomy has an impressive record of obtaining high time resolution observations, usually it is…

天体物理学 · 物理学 2009-11-10 S. D. Hyman , T. J. W. Lazio , N. E. Kassim , P. S. Ray , C. B. Markwardt , F. Yusef-Zadeh

Compact galactic and extragalactic radio sources can be imaged with an unsurpassed angular resolution of a few ten micro-arcseconds, adopting the observing technique of global millimeter VLBI. Here we present the Global Millimeter VLBI…

天体物理学 · 物理学 2007-05-23 T. P. Krichbaum , I. Agudo , U. Bach , A. Witzel , J. A. Zensus

Suzaku observed the Galactic center region near the Radio Arc at ~20' southeast of Sagittarius A*.In the 18'x18' field of view, we found four distinct X-ray sources: a bright star and a diffuse source associated with the star clusters in…

星系天体物理 · 物理学 2015-05-13 Ryosuke Fukuoka , Katsuji Koyama , Syukyo G. Ryu , Takeshi Go Tsuru

Low-luminosity radio-loud active galactic nuclei (AGN) are of importance in studies concerning feedback from radio AGN since a dominant fraction of AGN belong to this class. We report high-resolution Very Large Array (VLA) and European VLBI…

HR 8799 is an A5/F0 V star where exoplanets were first directly imaged. Four exoplanets were found within $\simeq 2\rlap.{''}0$ from the star. Here we report the VLA detection of a faint (19.1$\pm$2.7 $\mu$Jy) radio continuum (3.0 GHz)…

太阳与恒星天体物理 · 物理学 2024-07-09 Luis F. Rodriguez , Luis A. Zapata

The radio source 4C12.50 has often been suggested to be a prime candidate for the link between ultraluminous infrared galaxies and young radio galaxies. A VLBI study of the neutral hydrogen in the nuclear regions of this object shows that…

Compact radio cores are not only common in radio galaxies and quasars but also in many nearby galaxies with low-active, supermassive black holes. One famous example is the Galactic Center source Sgr A*. Recent studies of proper motions and…

天体物理学 · 物理学 2007-05-23 Heino Falcke

We present a 21-cm emission-absorption study towards extragalactic sources in the Canadian Galactic Plane Survey (CGPS). We have analyzed HI spectra towards 437 sources with S > 150 mJy, giving us a source density of 0.6 sources per square…

天体物理学 · 物理学 2009-11-10 S. T. Strasser , A. R. Taylor

The triple radio source detected in association with the luminous infrared source IRAS 16547-4247 has previously been studied with high angular resolution and high sensitivity with the Very Large Array (VLA) at 3.6-cm wavelength. In this…

The Galactic plane is a strong hard x-ray emitter and the emission forms a narrow continuous ridge. The currently known hard x-ray sources are far too few to explain the ridge x-ray emission, and the fundamental question as to whether the…

天体物理学 · 物理学 2009-11-07 Ken Ebisawa , Yoshitomo Maeda , Hidehiro Kaneda , Shigeo Yamauchi

M17 JVLA 35 is a radio source detected in projection against the M17 HII region. In recent observations, its spectrum between 4.96 and 8.46 GHz was found to be positive and very steep, with $\alpha \geq 2.9 \pm 0.6$ ($S_\nu \propto…

星系天体物理 · 物理学 2015-06-22 L. F. Rodriguez , C. Carrasco-Gonzalez , G. Montes , M. Tapia

We have searched for transient and/or variable radio sources in the field of Galactic micro-quasar Cygnus X-1 in 1.4 GHz (L band) using data from the Karl G. Jansky Very Large Array (JVLA). We used twenty years of data between 1983 and…

高能天体物理现象 · 物理学 2017-07-14 Sabyasachi Pal , Dusmanta Patra , Monique Hollick , Sandip K. Chakrabarti

We present Very Long Baseline Array (VLBA) HI absorption observations of the core region of the powerful radio galaxy Cygnus A. These data show both broad (FWHM = 231 \pm 21 km/s) and narrow (FWHM <30 km/s) velocity width absorption…

宇宙学与河外天体物理 · 物理学 2015-05-14 Christian Struve , John E. Conway

At present neutral atomic hydrogen (HI) gas in galaxies at redshifts above $z \sim 0.3$ (the extent of 21-cm emission surveys in individual galaxies) and below $z \sim 1.7$ (where the Lyman-$\alpha$ line is not observable with ground-based…

We present high angular resolution, high sensitivity 8.46 GHz (3.6 cm) radio continuum observations made toward the core of the HH~92 outflow with the Very Large Array in 2002-2003 and with the Expanded Very Large Array in 2011. We detect a…

太阳与恒星天体物理 · 物理学 2014-05-27 L. F. Rodriguez , B. Reipurth , H. -F. Chiang

PKS1830-211 is an unusually radio-loud gravitationally lensed quasar. In the radio, the system appears as two compact, dominant features surrounded by relatively extended radio emission which forms an Einstein Ring. As the line of sight to…

天体物理学 · 物理学 2016-08-30 Smita Mathur , Sunita Nair