scholarly journals Extragalactic maser surveys

2017 ◽  
Vol 13 (S336) ◽  
pp. 69-79 ◽  
Author(s):  
C. Henkel ◽  
J.-E. Greene ◽  
F. Kamali
Keyword(s):  
South Africa ◽  
Water Vapor ◽  
Low Frequency ◽  
Aperture Synthesis ◽  
Large Array ◽  
Future Perspectives ◽  
Very Large Array ◽  
Great Progress ◽  
Square Kilometer Array ◽  
Maser Sources

AbstractSince the IAU (maser-)Symposium 287 in Stellenbosch/South Africa (Jan. 2012), great progress has been achieved in studying extragalactic maser sources. Sensitivity has reached a level allowing for dedicated maser surveys of extragalactic objects. These included, during the last years, water vapor (H2O), methanol (CH3OH), and formaldehyde (H2CO), while surveys related to hydroxyl (OH), cyanoacetylene (HC3N) and ammonia (NH3) may soon become (again) relevant. Overall, with the upgraded Very Large Array (VLA), the Atacama Large Millimeter/submillimeter Array (ALMA), FAST (Five hundred meter Aperture Synthesis Telescope) and the low frequency arrays APERTIF (APERture Tile in Focus), ASKAP (Australian Square Kilometer Array Pathfinder) and MeerKAT (Meer Karoo Array Telescope), extragalactic maser studies are expected to flourish during the upcoming years. The following article provides a brief sketch of past achievements, ongoing projects and future perspectives.

scholarly journals Exciting maser science with new instruments – the promise of the EVLA

2007 ◽  
Vol 3 (S242) ◽  
pp. 496-505 ◽  
Author(s):  
Karl M. Menten
Keyword(s):  
High Resolution ◽  
Galactic Plane ◽  
Large Array ◽  
Very Large Array ◽  
Evolved Stars ◽  
Absorption Studies ◽  
Square Kilometer Array ◽  
Near Future ◽  
New Instruments ◽  
Maser Sources

AbstractIn the near future, the Expanded Very Large Array (EVLA) will allow surveys for maser sources with unprecedented sensitivity, spectral coverage and spectroscopic capabilities. In particular, comprehensive surveys for many maser species with simultaneous sensitive continuum imaging and absorption studies will give a comprehensive radio picture of star formation in the Galactic plane and elsewhere. Very efficient EVLA surveys for H2O megamasers in Active Galacic Nuclei will be possible to practically arbitrary redshifts.EVLA and Atacama Large Millimeter Array (ALMA) studies of H2O and SiO masers will serve as high resolution probes of the innermost envelopes of oxygen-rich evolved stars and HCN masers of carbon-rich stars.Farther in the future, the Square Kilometer Array (SKA) promises the detection of OH gigamasers at all conceivable redshifts and maser astrometry with unprecedented accuracy.

Mapping Mars water vapor with the very large array

Icarus ◽  
1992 ◽  
Vol 100 (1) ◽  
pp. 48-59 ◽  
Author(s):  
R.Todd Clancy ◽  
Arie W. Grossman ◽  
Duane O. Muhleman
Keyword(s):  
Water Vapor ◽  
Large Array ◽  
Very Large Array

scholarly journals Low frequency (74 MHz) radio continuum observations of the inner 13° × 7° of the Galactic center

2013 ◽  
Vol 9 (S303) ◽  
pp. 464-466
Author(s):  
M. Rickert ◽  
F. Yusef-Zadeh ◽  
C. Brogan
Keyword(s):  
High Resolution ◽  
Molecular Cloud ◽  
Supernova Remnant ◽  
Galactic Center ◽  
Low Frequency ◽  
Radio Continuum ◽  
Large Array ◽  
Very Large Array ◽  
Image Displays ◽  
Western Side

AbstractWe analyze a high resolution (114″ × 60″) 74 MHz image of the Galactic center taken with the Very Large Array (VLA). We have identified several absorption and emission features in this region, and we discuss preliminary results of two Galactic center sources: the Sgr D complex (G1.1–0.1) and the Galactic center lobe (GCL).The 74 MHz image displays the thermal and nonthermal components of Sgr D and we argue the Sgr D supernova remnant (SNR) is consistent with an interaction with a nearby molecular cloud and the location of the Sgr D Hii region on the near side of the Galactic center. The image also suggests that the emission from the eastern side of the GCL contains a mixture of both thermal and nonthermal sources, whereas the western side is primarily thermal.

scholarly journals Unveiling the nature of the unidentified gamma-ray sources: blazar counterparts at low radio frequencies

2013 ◽  
Vol 9 (S304) ◽  
pp. 95-95
Author(s):  
Francesco Massaro ◽  
R. D'Abrusco ◽  
M. Giroletti ◽  
A. Paggi ◽  
N. Masetti ◽  
...  
Keyword(s):  
Radio Emission ◽  
Gamma Ray ◽  
Low Frequency ◽  
Radio Galaxies ◽  
Large Array ◽  
New Approach ◽  
Very Large Array ◽  
Very Low Frequency ◽  
Sky Survey ◽  
Order Of Magnitude

AbstractAbout one third of the gamma-ray sources detected by Fermi have still no firmly established counterpart at lower energies. Here we propose a new approach to find candidate counterparts for the unidentified gamma-ray sources (UGSs) based on the 325 MHz radio survey performed with Westerbork Synthesis Radio Telescope (WSRT) in the northern hemisphere. First we investigate the low-frequency radio properties of blazars, the largest known population of gamma-ray sources; then we search for sources with similar radio properties combining the information derived from the Westerbork Northern Sky Survey (WENSS) with those of the NRAO VLA Sky survey (NVSS). We present a list of candidate counterparts for 32 UGSs with at least one counterpart in the WENSS. We also performed an extensive research in literature to look for infrared and optical counterparts of the gamma-ray blazar candidates selected with the low-frequency radio observations to confirm their nature. On the basis of our multifrequency research we identify 23 new gamma-ray blazar candidates out of 32 UGSs investigated. I will also present the first analysis of very low frequency radio emission of blazars based on the recent Very Large Array Low-Frequency Sky Survey (VLSS) at 74 MHz. I show that blazars present radio flat spectra when evaluated at 74 MHz, about an order of magnitude in frequency lower than previous analyses. The implications of these findings in the contest of the blazars – radio galaxies connection will be discussed.

scholarly journals Spatially Resolved Low-Frequency Very Large Array Observations of the Supernova Remnant 3C 391

2005 ◽  
Vol 130 (1) ◽  
pp. 148-155 ◽  
Author(s):  
C. L. Brogan ◽  
T. J. Lazio ◽  
N. E. Kassim ◽  
K. K. Dyer
Keyword(s):  
Supernova Remnant ◽  
Low Frequency ◽  
Large Array ◽  
Very Large Array ◽  
Spatially Resolved

scholarly journals VLSS redux: Software improvements applied to the Very Large Array Low-Frequency Sky Survey

Radio Science ◽  
2012 ◽  
Vol 47 (6) ◽  
pp. n/a-n/a ◽  
Author(s):  
W. M. Lane ◽  
W. D. Cotton ◽  
J. F. Helmboldt ◽  
N. E. Kassim
Keyword(s):  
Low Frequency ◽  
Large Array ◽  
Very Large Array ◽  
Sky Survey

scholarly journals Radio Images of Planetary Nebulae

1989 ◽  
Vol 131 ◽  
pp. 17-28 ◽  
Author(s):  
Yervant Terzian
Keyword(s):  
Magnetic Field ◽  
Neutral Hydrogen ◽  
Planetary Nebulae ◽  
Aperture Synthesis ◽  
Large Array ◽  
Very Large Array ◽  
Upper Limit ◽  
Neutral Material ◽  
Continuum Radio ◽  
The Continuum

The continuum radio spectra of planetary nebulae are discussed, and the structure of these objects is examined from the observed aperture synthesis brightness distributions determined with the Very Large Array. The use of radio observations in determining distances to planetary nebulae is examined. The detection of atomic neutral hydrogen at λ21 cm associated with planetary nebulae, as well as the associated CO and OH components are discussed. An upper limit, of the nebular magnetic field associated with the neutral material, of 1mG is reported for NGC 6302.

scholarly journals The 74 MHz System on the VLA

2002 ◽  
Vol 199 ◽  
pp. 447-454
Author(s):  
R.A. Perley ◽  
W.C. Erickson ◽  
N.E. Kassim
Keyword(s):  
Frequency Band ◽  
Low Frequency ◽  
Large Array ◽  
Paper Briefly ◽  
Very Large Array

The NRL and the NRAO have jointly implemented a low frequency capability on the Very Large Array. Operating at 73.8 MHz, this new frequency band offers unprecedented sensitivity (∼ 25mJy/beam) and resolution (∼ 25″). This paper briefly describes the this new receiving system, and the methodology for using it for astronomy.

Sign in / Sign up

Export Citation Format

Share Document