Absorption in Radio Sources of High Brightness Temperature

Nature ◽  
1963 ◽  
Vol 200 (4901) ◽  
pp. 56-57 ◽  
Author(s):  
P. J. S. WILLIAMS
Keyword(s):  
Brightness Temperature ◽  
Radio Sources ◽  
High Brightness

scholarly journals A Radio Survey For Gravitational Lenses In The Southern Hemisphere

1996 ◽  
Vol 173 ◽  
pp. 403-404
Author(s):  
J.E.J. Lovell ◽  
P.M. McCulloch ◽  
D.L. Jauncey
Keyword(s):  
Brightness Temperature ◽  
Southern Hemisphere ◽  
Gravitational Lens ◽  
Radio Sources ◽  
Gravitational Lenses ◽  
High Brightness ◽  
Spectrum Radio ◽  
Compact Array ◽  
Radio Survey

We are undertaking an imaging survey with the Australia Telescope Compact Array (ATCA) to find gravitational lens candidates in flat-spectrum Parkes Catalogue radio sources. Flat-spectrum radio sources typically possess a single high brightness temperature nucleus of milliarcsecond size. Such sources, if lensed, will show multiply imaged nuclei with separations that are large compared to their milliarcsecond sizes. Our flat-spectrum sample was selected using the criteria α2.7/5.0 > −0.5 (S(v) ∝ vα), S2.7 > 0.34Jy and δ ≤ −20°, and comprises a total of 461 sources.

A Gyro-Synchrotron Maser in the Solar Corona?

1978 ◽  
Vol 3 (3) ◽  
pp. 231-233 ◽  
Author(s):  
D. B. Melrose ◽  
S. M. White
Keyword(s):  
Synchrotron Radiation ◽  
Solar Corona ◽  
Brightness Temperature ◽  
Early Phase ◽  
Relativistic Electrons ◽  
High Brightness ◽  
Brightness Temperatures ◽  
Type Iv ◽  
Alternative Suggestion ◽  
Lower Frequencies

Stewart (1978) has reported four moving type IV bursts observed with the Culgoora radio heliograph at 43, 80 and 160 MHz. After an early phase, the brightness temperatures of the observed bursts decreased with increasing frequency and with time. The highest brightness temperature observed at 43 MHz was 1010K, and it seems that the brightness temperature would have been still higher at even lower frequencies. Existing theoretical ideas on moving type IV bursts are based on data (at 80 MHz primarily) which included no brightness temperatures in excess of 109K. the accepted interpretation involved gyro-synchrotron radiation from mildly relativistic electrons (energies ≈ 100 keV); reabsorption by the electrons themselves restricts the brightness temperature to less than about 100 keV ≈ 109K (Wild and Smerd 1972, Dulk 1973). Stewart’s (1978) new data at 43 MHz require that this accepted interpretation be modified; he has suggested that higher energy electrons are involved. An alternative suggestion is explored here, namely that the absorption might be negative. In other words, the high brightness temperatures observed could be due to a gyro-synchrotron maser involving electrons with energies of about 100 keV.

scholarly journals The Commensal Real-Time ASKAP Fast-Transients (CRAFT) Survey

2010 ◽  
Vol 27 (3) ◽  
pp. 272-282 ◽  
Author(s):  
Jean-Pierre Macquart ◽  
M. Bailes ◽  
N. D. R. Bhat ◽  
G. C. Bower ◽  
J. D. Bunton ◽  
...  
Keyword(s):  
Real Time ◽  
Data Stream ◽  
High Time Resolution ◽  
Radio Sources ◽  
Survey Experiment ◽  
High Brightness ◽  
Gravitational Fields ◽  
Fast Transients ◽  
Strong Gravitational Fields ◽  
The Universe

AbstractWe are developing a purely commensal survey experiment for fast (<5 s) transient radio sources. Short-timescale transients are associated with the most energetic and brightest single events in the Universe. Our objective is to cover the enormous volume of transients parameter space made available by ASKAP, with an unprecedented combination of sensitivity and field of view. Fast timescale transients open new vistas on the physics of high brightness temperature emission, extreme states of matter and the physics of strong gravitational fields. In addition, the detection of extragalactic objects affords us an entirely new and extremely sensitive probe on the huge reservoir of baryons present in the IGM. We outline here our approach to the considerable challenge involved in detecting fast transients, particularly the development of hardware fast enough to dedisperse and search the ASKAP data stream at or near real-time rates. Through CRAFT, ASKAP will provide the testbed of many of the key technologies and survey modes proposed for high time resolution science with the SKA.

scholarly journals The high brightness temperature of B0529+483 revealed by RadioAstron and implications for interstellar scattering

2017 ◽  
Vol 474 (3) ◽  
pp. 3523-3534 ◽  
Author(s):  
S V Pilipenko ◽  
Y Y Kovalev ◽  
A S Andrianov ◽  
U Bach ◽  
S Buttaccio ◽  
...  
Keyword(s):  
Brightness Temperature ◽  
High Brightness ◽  
Interstellar Scattering

scholarly journals An Update on Radio Supernovae

1998 ◽  
Vol 164 ◽  
pp. 357-358 ◽  
Author(s):  
Schuyler D. Van Dyk ◽  
Richard A. Sramek ◽  
Kurt W. Weiler ◽  
Marcos J. Montes ◽  
Nino Panagia
Keyword(s):  
Synchrotron Radiation ◽  
Radio Emission ◽  
Brightness Temperature ◽  
Power Law ◽  
Progress Report ◽  
Light Curves ◽  
High Brightness ◽  
Turn On ◽  
Distance Indicators ◽  
Circumstellar Environment

AbstractThe radio emission from supernovae (SNe) is nonthermal synchrotron radiation of high brightness temperature, with a “turn-on” delay at longer wavelengths, power-law decline after maximum with index β, and spectral index α asymptotically decreasing with time to a final, optically thin value. Radio supernovae (RSNe) are best described by the Chevalier (1982) “mini-shell” model, with modifications by Weiler et al. (1990). RSNe observations provide a valuable probe of the SN circumstellar environment and constraints on progenitor masses. We present a progress report on a number of recent RSNe, as well as on new behavior from RSNe 1979C and 1980K, and on RSNe as potential distance indicators. In particular, we present updated radio light curves for SN 1993J in M81.

scholarly journals DETECTION OF A HIGH BRIGHTNESS TEMPERATURE RADIO CORE IN THE ACTIVE-GALACTIC-NUCLEUS-DRIVEN MOLECULAR OUTFLOW CANDIDATE NGC 1266

2013 ◽  
Vol 779 (2) ◽  
pp. 173 ◽  
Author(s):  
Kristina Nyland ◽  
Katherine Alatalo ◽  
J. M. Wrobel ◽  
Lisa M. Young ◽  
Raffaella Morganti ◽  
...  
Keyword(s):  
Brightness Temperature ◽  
Active Galactic Nucleus ◽  
High Brightness ◽  
Molecular Outflow
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