scholarly journals Imaging point sources with the gravitational lens of an extended sun

2021 ◽  
Vol 104 (4) ◽  
Author(s):  
Slava G. Turyshev ◽  
Viktor T. Toth
Keyword(s):  
Point Sources ◽  
Gravitational Lens ◽  
Imaging Point

scholarly journals Imaging point sources in heterogeneous environments

2019 ◽  
Vol 35 (12) ◽  
pp. 125003
Author(s):  
Kui Ren ◽  
Yimin Zhong
Keyword(s):  
Point Sources ◽  
Heterogeneous Environments ◽  
Imaging Point

scholarly journals The 2dF Gravitational Lens Survey

2001 ◽  
Vol 18 (2) ◽  
pp. 192-194 ◽  
Author(s):  
Daniel J. Mortlock ◽  
Darren S. Madgwick ◽  
Ofer Lahav
Keyword(s):  
Cross Correlation ◽  
High Redshift ◽  
Point Sources ◽  
Gravitational Lens ◽  
Multiple Point ◽  
Quasar Spectra ◽  
Redshift Survey ◽  
Galaxy Redshift ◽  
Components Analysis ◽  
Correlation Techniques

AbstractThe 2 degree Field (2dF) galaxy redshift survey will involve obtaining spectra of approximately 2.5 105 objects which have previously been identified as galaxy candidates on morphological grounds. Included in these spectra should be about ten gravitationally-lensed quasars, all with low-redshift galaxies as deflectors (as the more common lenses with high-redshift deflectors will be rejected from the survey as multiple point-sources). The lenses will appear as superpositions of galaxy and quasar spectra, and either cross-correlation techniques or principal components analysis should be able to identify candidates systematically. With the 2dF survey approximately half-completed it is now viable to begin a methodical search for these spectroscopic lenses, and the first steps of this project are described here.

scholarly journals A Summary of the Observations of the Twin QSOs, 0957+561 A, B

1980 ◽  
Vol 92 ◽  
pp. 181-184
Author(s):  
Frederic H. Chaffee ◽  
Ray J. Weymann ◽  
Marc Davis ◽  
Nathaniel P. Carleton ◽  
D. Walsh ◽  
...  
Keyword(s):  
Emission Line ◽  
Absorption Line ◽  
Point Sources ◽  
The Other ◽  
Gravitational Lens ◽  
Time Interval ◽  
Radio Structure ◽  
Angular Extent ◽  
Relative Brightness ◽  
Time Variations

An analysis of all observations of the “twin” QSOs, 0957+561 A, B, to date does not yet allow us to distinguish between their being two nearly identical QSOs or a single QSO split into two images by an intervening gravitational lens. The more identical the two objects are found to be, the more difficult any explanation which postulates the existence of two distinct QSOs becomes. Jodrell Bank and VLA observations reveal additional radio structure to the northeast of the northern QSO image which, if physically associated with a single QSO doubly imaged by a gravitational lens, would itself be imaged weakly to the southwest. More detailed radio mapping should be able to test the existence of such an image.The VLBI map of Porcas and his collaborators reveals that the radio images corresponding to the optical ones are point sources separated by 6.175 arcsec having an angular extent to less than 20 milliarcseconds, whereas all further radio structure is resolved out.Optical spectroscopy of the twins reveals two nearly identical sources with indistinguishable emission line redshifts and with absorption line redshifts identical to within 15 km/sec. It is the identity of these optical characteristics which makes all non-gravitational lens hypotheses most difficult.The most compelling test of the lens hypothesis is the measurement of time variations of the two images at as many wavelengths as possible. If brightness variations of one image are repeated by the other after a time interval determined by the details of the observerlens-QSO geometry (such an interval could be of the order of many months or years) the lens hypothesis would be confirmed. Several observations indicate prior variations of the images, and programs to monitor their relative brightness in the future will be of great importance.

scholarly journals Spherical Aberration-Corrected Metalens for Polarization Multiplexed Imaging

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2774
Author(s):  
Shaodong Zhou ◽  
Kelei Xi ◽  
Songlin Zhuang ◽  
Qingqing Cheng
Keyword(s):  
Spherical Aberration ◽  
Beam Steering ◽  
Tomographic Imaging ◽  
Point Sources ◽  
Depth Of Focus ◽  
New Approach ◽  
Dynamic Phase ◽  
Multiplexed Imaging ◽  
Imaging Point ◽  
Aberration Corrected

We present a terahertz spherical aberration-corrected metalens that uses the dynamic phase to achieve polarization multiplexed imaging. The designed metalens has polarization–dependent imaging efficiencies and polarization extinction ratios that exceed 50% and 10:1, respectively. Furthermore, opposite gradient phases can be applied to orthogonal polarizations to shift the imaging of the two polarized sources in the longitudinal and transverse directions. Indeed, we find that the metalens has a smaller depth-of-focus than a traditional metalens when imaging point sources with limited objective lengths. These results provide a new approach for achieving multifunctional beam steering, tomographic imaging and chiroptical detection.

Seti Space Missions

1997 ◽  
Vol 161 ◽  
pp. 761-776 ◽  
Author(s):  
Claudio Maccone
Keyword(s):  
Electromagnetic Waves ◽  
Space Missions ◽  
Gravitational Lens ◽  
The Sun ◽  
Space Antenna ◽  
Focal Distance ◽  
Large Space ◽  
The Earth ◽  
Space Antennas ◽  
New Space

AbstractSETI from space is currently envisaged in three ways: i) by large space antennas orbiting the Earth that could be used for both VLBI and SETI (VSOP and RadioAstron missions), ii) by a radiotelescope inside the Saha far side Moon crater and an Earth-link antenna on the Mare Smythii near side plain. Such SETIMOON mission would require no astronaut work since a Tether, deployed in Moon orbit until the two antennas landed softly, would also be the cable connecting them. Alternatively, a data relay satellite orbiting the Earth-Moon Lagrangian pointL2would avoid the Earthlink antenna, iii) by a large space antenna put at the foci of the Sun gravitational lens: 1) for electromagnetic waves, the minimal focal distance is 550 Astronomical Units (AU) or 14 times beyond Pluto. One could use the huge radio magnifications of sources aligned to the Sun and spacecraft; 2) for gravitational waves and neutrinos, the focus lies between 22.45 and 29.59 AU (Uranus and Neptune orbits), with a flight time of less than 30 years. Two new space missions, of SETI interest if ET’s use neutrinos for communications, are proposed.

Resistance Monitor and Control for Vacuum Evaporation of Metals and Carbon

1976 ◽  
Vol 34 ◽  
pp. 572-573
Author(s):  
Russell L. Steere ◽  
Eric F. Erbe ◽  
J. Michael Moseley
Keyword(s):  
Electronic Device ◽  
Point Sources ◽  
High Contrast ◽  
Variable Resistor ◽  
Quality Of Results ◽  
Low Contrast ◽  
Evaporation Source ◽  
And Control ◽  
At Will

We have designed and built an electronic device which compares the resistance of a defined area of vacuum evaporated material with a variable resistor. When the two resistances are matched, the device automatically disconnects the primary side of the substrate transformer and stops further evaporation.This approach to controlled evaporation in conjunction with the modified guns and evaporation source permits reliably reproducible multiple Pt shadow films from a single Pt wrapped carbon point source. The reproducibility from consecutive C point sources is also reliable. Furthermore, the device we have developed permits us to select a predetermined resistance so that low contrast high-resolution shadows, heavy high contrast shadows, or any grade in between can be selected at will. The reproducibility and quality of results are demonstrated in Figures 1-4 which represent evaporations at various settings of the variable resistor.

A Spectroscopic Study of the Environments of Gravitational Lens Galaxies

2006 ◽  
Vol 20 ◽  
pp. 289-290
Author(s):  
I. Momcheva ◽  
K. Williams ◽  
C. Keeton ◽  
A. Zabludoff
Keyword(s):  
Spectroscopic Study ◽  
Gravitational Lens ◽  
Lens Galaxies

Simulation of a gravitational lens in a lecture demonstration

1982 ◽  
Vol 138 (9) ◽  
pp. 147 ◽  
Author(s):  
G.S. Egorov ◽  
Nikolai S. Stepanov
Keyword(s):  
Gravitational Lens ◽  
Lecture Demonstration

EVALUATION OF MOUNTAIN AREA AS NON-POINT SOURCE OF NITROGEN FOR SETO INLAND SEA: THE NORTHERN SHIKOKU REGION, JAPAN

2017 ◽  
Author(s):  
Shohei Morisawa ◽  
Shohei Morisawa ◽  
Yukio Komai ◽  
Yukio Komai ◽  
Takao Kunimatsu ◽  
...  
Keyword(s):  
Average Concentration ◽  
Point Sources ◽  
Seto Inland Sea ◽  
Mountain Streams ◽  
Unit Load ◽  
Mountain Areas ◽  
Mountain Area ◽  
The Seto Inland Sea ◽  
Unit Load Method ◽  
Important Position

The northern Shikoku region is located in the Western part of Japan and faces towards the Seto Inland Sea. The forest area, which is one of the non-point sources in the Seto Inland Sea watershed, occupies 75% of the land use in the watershed of the northern Shikoku region. The amount of loadings of nutrients and COD in the Seto Inland Sea has been estimated by the unit load method but actually the data has not been investigated. It is however, necessary to know the real concentration of nitrogen in mountain streams to evaluate the role which is the mountain area plays as non-point sources. Therefore, more water samples of mountain streams in the watershed need to be taken and the concentrations of nitrogen analyzed. The mountain streams in the northern Shikoku area were investigated from April, 2015 to November, 2015. The number of sampling sites was 283, in addition to the past data by Kunimatsu et al. The average concentration of nitrate nitrogen in Ehime, Kagawa, and Tokushima was 0.61mg/L, 0.78mg/L and 0.34mg/L, respectively. The environmental standard range for nitrogen in the Seto Inland Sea is from between less than 0.2mg/L and less than 1mg/L. Therefore, the average concentration of nitrogen in these regions was over category II, and those of mountain streams in Kagawa Prefecture exceeded category III. About 20% of mountain streams were more than 1mg/L. It has become clear that mountain areas occupy an important position as non-point sources for the Seto Inland Sea.

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