The Compact Nonthermal Radio Source at the Galactic Center: An Update

1989 ◽  
pp. 527-534 ◽  
Author(s):  
K. Y. Lo
Keyword(s):  
Radio Source ◽  
Galactic Center ◽  
Nonthermal Radio

scholarly journals The Compact Nonthermal Radio Source at the Galactic Center: an Update

1989 ◽  
Vol 136 ◽  
pp. 527-534
Author(s):  
K. Y. Lo
Keyword(s):  
Radio Source ◽  
Galactic Center ◽  
Central Star ◽  
Radio Sources ◽  
Stellar Objects ◽  
Nonthermal Radio ◽  
Compact Radio Source ◽  
The Galaxy ◽  
Observational Status ◽  
Sgr A

We review the current observational status of Sgr A∗, the compact nonthermal radio source at the galactic center. Sgr A∗ is a unique radio source at a unique location of the Galaxy. It is unlike any compact radio source associated with known stellar objects, but it is similar to extragalactic nuclear compact radio sources. The positional offset between Sgr A∗ and IRS16 places little constraint on the nature of the underlying energy source, since IRS16 need not be the core of the central star cluster. Sgr A∗ is still the best candidate for marking the location of a massive collapsed object.

scholarly journals The Galactic Center

1984 ◽  
Vol 110 ◽  
pp. 265-273
Author(s):  
K. Y. Lo
Keyword(s):  
High Resolution ◽  
Radio Source ◽  
Galactic Center ◽  
Minor Axis ◽  
Ionized Gas ◽  
Nonthermal Radio ◽  
The Galaxy ◽  
First Time ◽  
Source Structure

The center of our Galaxy contains an extremely compact nonthermal radio source. For the first time, elongation in the source structure has been detected. The long axis is nearly aligned with the minor axis of the Galaxy. Recent high resolution observations of the ionized gas within the central 3 parsecs suggest that matter may be falling in towards the center. This has interesting implications on the processes within our Galactic nucleus.

scholarly journals G359.3–0.82: An Unusual Radio Source

1989 ◽  
Vol 136 ◽  
pp. 197-204
Author(s):  
F. Yusef-Zadeh ◽  
F. Yusef-Zadeh
Keyword(s):  
Radio Emission ◽  
Interstellar Medium ◽  
Radio Source ◽  
Relative Velocity ◽  
Galactic Center ◽  
Extragalactic Radio Source ◽  
Compact Source ◽  
Nonthermal Radio ◽  
Galactic Object

An unusual radio source exhibiting an axisymmetric, cometary morphology was recently reported by Yusef-Zadeh and Bally (1987) near the Galactic center. This source, G359.3–0.82, consists of a bright head containing a compact source followed by a tail exhibiting sinuous structure. Radio emission is highly polarized and has a nearly flat spectrum between λ6cm and λ20cm. Its location in the sky, spectrum, and lack of resemblance to any other extragalactic radio source suggested to us that this radio source is a Galactic object possibly lying near the Galactic center. New high-reslolution radio images obtained using the VLA confirm the remarkable morphology and strengthen the distinction between G359.3–0.82 and any known extragalactic radio source. The characteristics of G359.3–0.82 suggest that it may be a nonthermal radio wake produced by an object moving through the interstellar medium at a high relative velocity.

scholarly journals Turbulent Origin of the Galactic Center Magnetic Field: Nonthermal Radio Filaments

2006 ◽  
Vol 637 (2) ◽  
pp. L101-L104 ◽  
Author(s):  
Stanislav Boldyrev ◽  
Farhad Yusef-Zadeh
Keyword(s):  
Magnetic Field ◽  
Galactic Center ◽  
Nonthermal Radio

scholarly journals THE UNUSUAL GALACTIC CENTER RADIO SOURCE N3

2016 ◽  
Vol 826 (2) ◽  
pp. 218 ◽  
Author(s):  
D. A. Ludovici ◽  
C. C. Lang ◽  
M. R. Morris ◽  
R. Mutel ◽  
E. A. C. Mills ◽  
...  
Keyword(s):  
Radio Source ◽  
Galactic Center

scholarly journals Long-Term Variations of the Compact Radio Source Sgr A∗ at the Galactic Center

1989 ◽  
Vol 136 ◽  
pp. 535-541 ◽  
Author(s):  
Jun-Hui Zhao ◽  
R. D. Ekers ◽  
W. M. Goss ◽  
K. Y. Lo ◽  
Ramesh Narayan
Keyword(s):  
Radio Source ◽  
Flux Density ◽  
High Velocity ◽  
Galactic Center ◽  
Light Curves ◽  
Radio Flux ◽  
Compact Radio Source ◽  
Sgr A ◽  
Long Term Variations

We investigate the long-term flux density variations of the compact radio source Sgr A∗ at the galactic center by combining recent VLA observations with previous Green Bank interferometer data. We present radio flux density light-curves for Sgr A∗ at 20, 11, 6 and 3.7 cm from 1974 to 1987. Long-term variability with a timescale of at least 5 years is seen at 20 cm and there is evidence for more rapid variations at the shorter wavelengths. The variability timescales at 20, 11 and 6 cm fit the λ2 scaling predicted by the theory of refractive scintillation suggesting that the variability could be due to this cause. However, the timescales are relatively short, implying an unusually high velocity in the scattering screen. The modulation index of the variability is large and relatively independent of wavelength.

An angular size for the compact radio source at the galactic center

1977 ◽  
Vol 218 ◽  
pp. 668 ◽  
Author(s):  
K. Y. Lo ◽  
M. H. Cohen ◽  
R. T. Schilizzi ◽  
H. N. Ross
Keyword(s):  
Radio Source ◽  
Galactic Center ◽  
Angular Size ◽  
Compact Radio Source
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