scholarly journals Radio Emission from the Seyfert Galaxy NGC 5548

1982 ◽  
Vol 97 ◽  
pp. 191-192
Author(s):  
J. S. Ulvestad ◽  
A. S. Wilson ◽  
D. G. Wentzel
Keyword(s):  
High Resolution ◽  
Radio Emission ◽  
Radio Source ◽  
Seyfert Galaxy ◽  
Central Component ◽  
The Galaxy ◽  
Ngc 5548

Weak radio emission from the type 1.5 Seyfert galaxy NGC 5548 has been mapped with high resolution at the VLA at both 1465 and 4885 MHz. The galaxy contains the largest (5.9 kpc) triple radio source known in a Seyfert galaxy. The central component of that triple is unresolved (<0.39×0.15 kpc) and has a flatter spectrum than the well-resolved outer lobes. In addition, the field surrounding NGC 5548 and two of the sources in that field have been mapped at 1465 MHz; the field sources are unlikely to be physically associated with NGC 5548.

Radio Emission from the Seyfert Galaxy NGC 5548

1982 ◽  
pp. 191-192
Author(s):  
J. S. Ulvestad ◽  
A. S. Wilson ◽  
D. G. Wentzel
Keyword(s):  
Radio Emission ◽  
Seyfert Galaxy ◽  
Ngc 5548

scholarly journals The Radio Core of Markarian 348

1984 ◽  
Vol 110 ◽  
pp. 263-264
Author(s):  
S. G. Neff ◽  
A. G. de Bruyn
Keyword(s):  
Radio Source ◽  
Seyfert Galaxy ◽  
Small Scale ◽  
Early Type ◽  
Disc Galaxy ◽  
Relative Proximity ◽  
The Galaxy ◽  
Continuum Radio ◽  
The Continuum

The type 2 Seyfert galaxy Markarian 348 (NGC 262) is a normal early-type disc galaxy (SO/a or Sa) surrounded by a very large HI envelope. The continuum radio source in the galaxy is unresolved by conventional interferometers on scales as small as an arcsecond, is variable on time scales of a few months, and is quite strong by Seyfert standards (300 mJy). Mkn 348 is relatively nearby, allowing one to study very small-scale structure in the galaxy (at the assumed distance of 60 Mpc (Ho = 75 km/sec/Mpc), one light year subtends an angle of about one mas). Both the relative proximity and the radio source strength make it a good candidate for VLBI studies.

scholarly journals The Two-Sided VLBI Source in the Seyfert Galaxy Mrk 231

1998 ◽  
Vol 164 ◽  
pp. 199-200 ◽  
Author(s):  
J. S. Ulvestad ◽  
J. M. Wrobel ◽  
C. L. Carilli
Keyword(s):  
Radio Source ◽  
Seyfert Galaxy ◽  
Central Component ◽  
Linear Scale ◽  
Radio Image ◽  
Total Size ◽  
The Core

AbstractThe Seyfert 1/starburst/IR galaxy Mrk 231 (UGC 08058), at z = 0.0422, has been imaged with the VLBA at frequencies ranging from 1.4 GHz to 22 GHz. The radio image shows a triple source of total size 50 mas (30h−1 pc), with a self-absorbed central component and two detached lobes. The northern lobe, located 12h−1 pc from the core, is free-free absorbed at the lowest frequencies; there also seems to be free-free absorption in the southern component. The linear scale over which this absorption takes place is several times larger than that seen in NGC1275/3C84.The axis of the 50-mas radio source is approximately 60° from the elongation of the central component on the 1-mas scale. The spectrum of this central component becomes optically thin between 5 and 8.4 GHz, and resolves into a small triple source of size ~ 1.0h−1 pc at 15 GHz. There is no hint of a jet or other structure directly connecting this central component to the outer VLBI lobes.

scholarly journals Extreme Emission Line Outflows in the GPS Source 4C 12.50 (PKS 1345+12)

2003 ◽  
Vol 20 (1) ◽  
pp. 25-27 ◽  
Author(s):  
J. Holt ◽  
C. N. Tadhunter ◽  
R. Morganti
Keyword(s):  
High Resolution ◽  
Emission Line ◽  
Radio Source ◽  
Spectral Coverage ◽  
La Palma ◽  
Upper Limit ◽  
Line Region ◽  
The Galaxy ◽  
William Herschel

AbstractWe present high resolution spectra (0.7 Å/pix) of the GPS source 4C 12.50 with large spectral coverage (˜4500 Å) taken with the 4.2 m William Herschel Telescope, La Palma. The slit was aligned along PA 160° to include the nucleus and emission line region to the NW. An asymmetric halo extending 20 kpc NW and 12 kpc SE from the nucleus is clearly seen. At the position of the nucleus we observe unusually broad forbidden emission line components (broadest component: FWHM ˜ 2000 km s−1), blue shifted by up to 2000 km s−1 with respect to the halo of the galaxy and HI absorption. We interpret this as material in outflow. We measure E(B–V) = 1.44 for the broadest, most kinematically disturbed component, corresponding to an actual Hβ flux 130 times brighter than that measured. We calculate an upper limit for the mass of the line emitting gas of order 106 M⊙ for both the intermediate and broad components. Our results are consistent with 4C 12.50 being a young radio source.

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 The nature of the radio source Cygnus X

1959 ◽  
Vol 9 ◽  
pp. 339-346 ◽  
Author(s):  
F. D. Drake
Keyword(s):  
High Resolution ◽  
Radio Source ◽  
Optical Observation ◽  
Thermal Spectrum ◽  
The Galaxy ◽  
Spiral Arm

The radio source Cygnus X (IAU 20N4A) has long created interest because of its unusual spectrum, its seemingly extended nature, and its location in a region where we believe we look nearly lengthwise down a spiral arm of the Galaxy. Piddington and Minnett [1] first showed that the source had a thermal spectrum. In a recent paper Davies [2] has concluded that the source is an extremely large extended HII region located in the second spiral arm in Cygnus. The recent construction of large parabolic antennas has made it possible to clarify greatly the nature of Cygnus X; it is the purpose of this paper to give the results of a high-resolution survey of the Cygnus X region, and to report a possibly relevant optical observation.

Radio Emission from the Seyfert Galaxy NGC 5548

1982 ◽  
pp. 191-192
Author(s):  
J. S. Ulvestad ◽  
A. S. Wilson ◽  
D. G. Wentzel
Keyword(s):  
Radio Emission ◽  
Seyfert Galaxy ◽  
Ngc 5548

scholarly journals A Probable BL Lac Object with Absorption Redshift 1.49

1980 ◽  
Vol 92 ◽  
pp. 131-132
Author(s):  
R. W. Hunstead ◽  
J. C. Blades ◽  
H. S. Murdoch
Keyword(s):  
High Resolution ◽  
Radio Source ◽  
Optical Variability ◽  
Optical Polarization ◽  
Absorption System ◽  
No Emission ◽  
Central Source ◽  
Bl Lac ◽  
The Galaxy ◽  
Absorption Redshift

The radio source 1309–216 is identified with an 18m stellar object having a steep non-thermal continuum (α = 2.6, fν α ν−α) with no emission features. High resolution spectra obtained with the AAT reveal strong absorption due to the CIV doublet at redshifts 1.361, 1.489 and 1.491. In the strongest absorption system (za = 1.489) the SiIV doublet and possibly SiII are also detected. No information on the optical polarization is available but spectrophotometry at several epochs shows evidence for optical variability and the object is therefore classified tentatively as a BL Lac object.The species found in absorption in 1309–216 are consistent either with ejection from a central source or absorption in the haloes of intervening galaxies. The velocity dispersions and column densities derived for the absorbing regions are comparable to those for gas in the LMC and in the halo of the galaxy.

scholarly journals The Absorption by the Interstellar Medium of 80 MHz Radio Emission from Galactic Supernova Remnants

1972 ◽  
Vol 25 (4) ◽  
pp. 429 ◽  
Author(s):  
GA Dulk ◽  
OB Slee
Keyword(s):  
High Resolution ◽  
Radio Emission ◽  
Interstellar Medium ◽  
Flux Density ◽  
Electron Density ◽  
Supernova Remnants ◽  
Line Of Sight ◽  
The Galaxy

High resolution 80 MHz observations of 20 galactic supernova remnants have been made with the Culgoora radioheliograph. More than half of the sources have an unexpectedly low flux density at 80 MHz, probably as a result of free?free absorption taking place in the inner arms of the Galaxy. The observations imply an r.m.s. electron density of about 0�1?0�5 cm?3 along the line of sight. This large value for the electron density seems to require a greater ionizing flux than that which occurs in the solar vicinity.

The GLEAM 4-Jy Sample: The brightest radio-sources in the southern sky

2019 ◽  
Vol 15 (S356) ◽  
pp. 375-375
Author(s):  
Sarah White
Keyword(s):  
Radio Emission ◽  
Active Galactic Nuclei ◽  
Visual Inspection ◽  
Low Frequency ◽  
Galactic Nuclei ◽  
Radio Sources ◽  
Relativistic Jets ◽  
The Galaxy ◽  
Murchison Widefield Array ◽  
Past Activity

AbstractLow-frequency radio emission allows powerful active galactic nuclei (AGN) to be selected in a way that is unaffected by dust obscuration and orientation of the jet axis. It also reveals past activity (e.g. radio lobes) that may not be evident at higher frequencies. Currently, there are too few “radio-loud” galaxies for robust studies in terms of redshift-evolution and/or environment. Hence our use of new observations from the Murchison Widefield Array (the SKA-Low precursor), over the southern sky, to construct the GLEAM 4-Jy Sample (1,860 sources at S151MHz > 4 Jy). This sample is dominated by AGN and is 10 times larger than the heavily relied-upon 3CRR sample (173 sources at S178MHz > 10 Jy) of the northern hemisphere. In order to understand how AGN influence their surroundings and the way galaxies evolve, we first need to correctly identify the galaxy hosting the radio emission. This has now been completed for the GLEAM 4-Jy Sample – through repeated visual inspection and extensive checks against the literature – forming a valuable, legacy dataset for investigating relativistic jets and their interplay with the environment.

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