Upper Limits to Gamma Ray Fluxes from Three Pulsating Radio Sources

Nature ◽  
1968 ◽  
Vol 220 (5170) ◽  
pp. 892-893 ◽  
Author(s):  
G. G. FAZIO ◽  
H. F. HELMKEN ◽  
G. H. RIEKE ◽  
T. C. WEEKES
Keyword(s):  
Gamma Ray ◽  
Radio Sources ◽  
Upper Limits

scholarly journals Constraining Einstein’s equivalence principle with multiwavelength polarized astrophysical sources

2020 ◽  
Vol 498 (3) ◽  
pp. 4295-4302
Author(s):  
Shuang-Xi Yi ◽  
Yuan-Chuan Zou ◽  
Jun-Jie Wei ◽  
Qi-Qi Zhou
Keyword(s):  
Equivalence Principle ◽  
Time Delays ◽  
Gamma Ray ◽  
Polarization Measurement ◽  
Radio Sources ◽  
Polarization Rotation ◽  
Milky Way Galaxy ◽  
Upper Limits ◽  
Single Polarization ◽  
Einstein's Equivalence Principle

ABSTRACT The observed time delays between photons with different circular polarizations from an astrophysical object provide a new, interesting way of testing the Einstein Equivalence Principle (EEP). In this paper, we constrain the EEP by considering both Shapiro time delay and Faraday rotation effects. We continue to search for astronomical sources that are suitable for testing the EEP accuracy, and obtain 60 extragalactic radio sources with multiwavelength polarization angles in three different radio bands (20, 8.6, and 4.8 GHz) and 29 brightest stars within our own Milky Way galaxy with multicolour linear polarimetric data in five optical bands (UBVRI). We apply the Metropolis–Hastings Markov Chain to simulate the fit parameters. The final results show that the values of the parametrized post-Newtonian parameter γ discrepancy (Δγp) are constrained to be in the range of 10−26 − 10−23 for 60 radio sources and in the range of 10−23 − 10−20 for 29 optical polarization stars. Compared to previous EEP tests that based on the single polarization measurement in the gamma-ray band, our results have profound superiority that nearly a few tens of astrophysical sources with multiwavelength polarization observations commonly in the optical and radio bands are available. It ensures that these sources can give more significantly robust bounds on the EEP. Although the presented method is straightforward, the resulting constraints on the EEP should be taken as upper limits as other more complex astrophysical effects affecting a polarization rotation are hardly considered.

scholarly journals Upper limits on the high-energy emission from gamma-ray bursts observed by AGILE-GRID

2012 ◽  
Vol 547 ◽  
pp. A95 ◽  
Author(s):  
F. Longo ◽  
E. Moretti ◽  
L. Nava ◽  
R. Desiante ◽  
M. Olivo ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Energy Emission ◽  
Upper Limits ◽  
High Energy Emission

scholarly journals SEARCH FOR NEUTRINO EMISSION FROM GAMMA-RAY SOURCES WITH THE ANTARES TELESCOPE

2012 ◽  
Vol 08 ◽  
pp. 307-310
Author(s):  
C. BIGONGIARI
Keyword(s):  
Gamma Ray ◽  
Neutrino Flux ◽  
Three Dimensional ◽  
Effective Area ◽  
High Energy ◽  
Neutrino Telescope ◽  
Neutrino Detector ◽  
Upper Limits ◽  
Cosmic Neutrino ◽  
Promising Source

ANTARES is the first undersea neutrino detector ever built and presently the neutrino telescope with the largest effective area operating in the Northern Hemisphere. A three-dimensional array of photomultiplier tubes detects the Cherenkov light induced by the muons produced in the interaction of high energy neutrinos with the matter surrounding the detector. The detection of astronomical neutrino sources is one of the main goals of ANTARES. The search for point-like neutrino sources with the ANTARES telescope is described and the preliminary results obtained with data collected from 2007 to 2010 are shown. No cosmic neutrino source has been observed and neutrino flux upper limits have been calculated for the most promising source candidates.

scholarly journals CALET UPPER LIMITS ON X-RAY AND GAMMA-RAY COUNTERPARTS OF GW151226

2016 ◽  
Vol 829 (1) ◽  
pp. L20 ◽  
Author(s):  
O. Adriani ◽  
Y. Akaike ◽  
K. Asano ◽  
Y. Asaoka ◽  
M. G. Bagliesi ◽  
...  
Keyword(s):  
Gamma Ray ◽  
X Ray ◽  
Upper Limits

Radio Sources, Quasars, Pulsars, Infrared, X-Ray, Gamma-Ray Sources, Cosmic Radiation

1976 ◽  
pp. 396-452
Author(s):  
S. Böhme ◽  
U. Esser ◽  
W. Fricke ◽  
U. Güntzel-Lingner ◽  
I. Heinrich ◽  
...  
Keyword(s):  
Cosmic Radiation ◽  
Gamma Ray ◽  
Radio Sources ◽  
X Ray

Radio Sources, Quasars, Pulsars, Infrared, X-Ray, Gamma-Ray Sources, Cosmic Radiation

1974 ◽  
pp. 388-416
Author(s):  
S. Böhme ◽  
U. Esser ◽  
W. Fricke ◽  
U. Güntzel-Lingner ◽  
F. Henn ◽  
...  
Keyword(s):  
Cosmic Radiation ◽  
Gamma Ray ◽  
Radio Sources ◽  
X Ray

Radio Sources, Quasars, Pulsars, X Ray-, Gamma Ray-Sources, Cosmic Radiation

1972 ◽  
pp. 376-411
Author(s):  
S. Böhme ◽  
W. Fricke ◽  
U. Güntzel-Lingner ◽  
F. Henn ◽  
D. Krahn ◽  
...  
Keyword(s):  
Cosmic Radiation ◽  
Gamma Ray ◽  
Radio Sources ◽  
X Ray

scholarly journals VLBI Observations of Southern EGRET Identifications

1996 ◽  
Vol 175 ◽  
pp. 19-20
Author(s):  
J.E.J. Lovell ◽  
S.J. Tingay ◽  
P.G. Edwards ◽  
D.L. Jauncey ◽  
R.A. Preston
Keyword(s):  
High Resolution ◽  
Southern Hemisphere ◽  
Gamma Ray ◽  
Radio Sources ◽  
Vlbi Observations ◽  
First Results

We present high resolution VLBI images of three southern radio sources: PKS 0208–512, PKS 0521–365 and PKS 0537–441. These sources have been identified as > 100 MeV gamma-ray sources with the Energetic Gamma-Ray Telescope (EGRET) on board the Compton Gamma-Ray Observatory (Thompson et al. 1995). These are the first results in a continuing program of VLBI observations of southern EGRET identifications with the Southern Hemisphere VLBI Experiment (SHEVE) array of telescopes (Jauncey et al., 1994).

scholarly journals Radio Reference Frame Stability from VLBI Data

1988 ◽  
Vol 129 ◽  
pp. 331-332
Author(s):  
O. J. Sovers ◽  
R. N. Treuhaft
Keyword(s):  
Reference Frame ◽  
Independent Sets ◽  
Radio Sources ◽  
Deep Space ◽  
Deep Space Network ◽  
Space Network ◽  
Rates Of Change ◽  
Upper Limits ◽  
Vlbi Data ◽  
Almost All

Intercontinental radio interferometric measurements between NASA's Deep Space Network stations yield a catalog of positions of 106 extragalactic radio sources, uniformly distributed between −45° and +85° declination. Almost all of the source positions have formal uncertainties between 0.5 and 3 milliarcseconds. Estimates of three independent sets of 32 source coordinates at average epochs 1980.0, 1983.2, and 1984.5 assess the level of stability of the reference frame over a five-year period. Comparisons of the three sets of source coordinates show a number of cases of > 2σ differences, particularly betwen the 1984–85 and 1981–83 periods. No sources, however, show 2σ shifts among both pairs of epochs. Upper limits of the order of 1 mas/yr can be placed on the time rates of change of the 32 source coordinates.

scholarly journals A VLA Search for the Geminga Pulsar at 74 and 326 MHz

2000 ◽  
Vol 177 ◽  
pp. 239-240
Author(s):  
Namir E. Kassim ◽  
T. Joseph ◽  
W. Lazio
Keyword(s):  
Flux Density ◽  
Gamma Ray ◽  
Low Frequency ◽  
Intrinsic Variability ◽  
Upper Limits

AbstractWe have used the VLA to image the location of the gamma-ray pulsar Geminga at 74 and 326 MHz. Upper limits to the pulse-averaged flux density, taking diffractive scintillation (DISS) into account, areS< 56 mJy (2σ; DISS quenched) at 74 MHz andS< 5 mJy (95% confidence) at 326 MHz. Intrinsic variability appears to be required in order to reconcile our upper limits with previous low-frequency detections.

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