New results from testing relativistic gravity with radio pulsars

2022 ◽  
Author(s):  
Michael Kramer
Keyword(s):  
Black Hole ◽  
Radio Astronomy ◽  
Relativistic Astrophysics ◽  
Radio Pulsars ◽  
Microwave Background ◽  
Binary Pulsars ◽  
Lab Experiments ◽  
Complementary Role ◽  
Near Future ◽  
New Instruments

We experience a golden era in testing and exploring relativistic gravity. Whether it is results from gravitational-wave detectors, satellite or lab experiments, radio astronomy plays an important complementary role. Here, one can mention the cosmic microwave background, black hole imaging and, obviously, binary pulsars. This talk will concentrate on the latter and new results from studies of strongly self-gravitating bodies with unrivalled precision. This presentation compares the results to other methods, discusses implications for other areas of relativistic astrophysics and will give an outlook of what we can expect from new instruments in the near future.

scholarly journals The Future of Radio Astronomy: Options for Dealing with Human Generated Interference

2001 ◽  
Vol 196 ◽  
pp. 199-208 ◽  
Author(s):  
R. D. Ekers ◽  
J. F. Bell
Keyword(s):  
Radio Astronomy ◽  
Galactic Nuclei ◽  
Thermal Processes ◽  
Microwave Background ◽  
New Science ◽  
Future Success ◽  
The Future ◽  
Technological Developments ◽  
The Universe ◽  
New Instruments

Radio astronomy provides a unique window on the universe, allowing us to study non-thermal processes (e.g. galactic nuclei, quasars, pulsars) at the highest angular resolution using VLBI, with low opacity. It is the most interesting waveband for SETI searches. To date it has yielded three Nobel prizes (microwave background, pulsars, gravitational radiation). There are both exciting possibilities and substantial challenges for radio astronomy to remain at the cutting edge over the next three decades. New instruments like ALMA and the SKA will open up new science if the challenge of dealing with human generated interference can be met. We summarise some of the issues and technological developments that will be essential to the future success of radio astronomy.

scholarly journals On the peculiarities in the spin-down of isolated radio pulsars

2012 ◽  
Vol 8 (S291) ◽  
pp. 208-208
Author(s):  
Augustine Chukwude
Keyword(s):  
Radio Astronomy ◽  
Time Resolution ◽  
Local Phase ◽  
Astronomy Observatory ◽  
Radio Pulsars ◽  
Short Term ◽  
Radio Astronomy Observatory ◽  
Long Term Changes ◽  
Timing Data

AbstractWe investigate the spin-down behaviour of a sample of 25 radio pulsars on decadal timescales (~ 18 years) using a continuous timing data obtained over a period of at Hartebeesthoek Radio Astronomy Observatory (HartRAO). Particular attention is placed on achieving a better time resolution of both the short-term and long-term changes in pulsar spin-down using local phase-coherent measurements of the spin-down rates (). We demonstrate that the spin-down of radio pulsars is generally complicated by a superposition of processes that may or may not be related. Specifically, our results show that (i) for 7 pulsars, the observed spin-down variation is largely stochastic, characterized by random and sustained jumps in of varying amplitudes, (ii) for 9 objects, the spin-down evolution shows dominant monotonic variations in superimposed on short-term stochastic jumps in the parameter, and (iii) for the remaining 9 pulsars, the long-term spin-down evolution is non-monotonic, dominated by some systematic excursion in the measured spin-down rates.

3. Extrasolar tests of gravity

2017 ◽  
pp. 35-45
Author(s):  
Timothy Clifton
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Field ◽  
Solar System ◽  
Neutron Stars ◽  
Event Horizon ◽  
Gravitational Fields ◽  
Binary Pulsars ◽  
Tests Of Gravity ◽  
Triple Star

By studying objects outside our Solar System, we can observe star systems with far greater gravitational fields. ‘Extrasolar tests of gravity’ considers stars of different sizes that have undergone gravitational collapse, including white dwarfs, neutron stars, and black holes. A black hole consists of a region of space-time enclosed by a surface called an event horizon. The gravitational field of a black hole is so strong that anything that finds its way inside the event horizon can never escape. Other star systems considered are binary pulsars and triple star systems. With the invention of even more powerful telescopes, there will be more tantalizing possibilities for testing gravity in the future.

scholarly journals Weak and strong deflection gravitational lensing by a renormalization group improved Schwarzschild black hole

2019 ◽  
Vol 79 (12) ◽  
Author(s):  
Xu Lu ◽  
Yi Xie
Keyword(s):  
Black Hole ◽  
Renormalization Group ◽  
Gravitational Lensing ◽  
Galactic Center ◽  
Quantum Effect ◽  
Apparent Size ◽  
Great Care ◽  
Schwarzschild Black Hole ◽  
Sgr A ◽  
Near Future

AbstractWeak and strong deflection gravitational lensing by a renormalization group improved Schwarzschild black hole is investigated and its observables are found. By taking the supermassive black holes Sgr A* and M87* respectively in the Galactic Center and at the center of M87 as lenses, we estimate these observables and analyse possibility of detecting this quantum improvement. It is not feasible to distinguish such a black hole by most observables in the near future except for the apparent size of the shadow. We also note that directly using measured shadow of M87* to constrain this quantum effect requires great care.

scholarly journals Recent and Future Studies of Circumstellar Matter – A Snapshot

1999 ◽  
Vol 191 ◽  
pp. 603-610
Author(s):  
M. Jura
Keyword(s):  
Mass Loss ◽  
Theoretical Models ◽  
Circumstellar Matter ◽  
Agb Stars ◽  
Future Studies ◽  
Instruments And Techniques ◽  
Near Future ◽  
New Instruments ◽  
Loss Mechanisms

At this meeting, powerful new images and spectroscopy of AGB stars were presented. Theoretical models have advanced, and we are learning more from studies of the pre-solar grains isolated from meteorites.We suggest that several mass loss mechanisms may be operating in AGB stars: current images imply both spherical winds and highly flattened outflows. There are good arguments that in some cases, a companion may be critical in driving the final outflow. In the near future, a number of extremely powerful new instruments and techniques will be available that will lead to a much deeper understanding of these systems.

scholarly journals Interpretation of Cosmological Information on Radio Sources

1977 ◽  
Vol 74 ◽  
pp. 247-257
Author(s):  
G. Burbidge
Keyword(s):  
Radio Astronomy ◽  
Background Radiation ◽  
Radio Galaxies ◽  
Radio Sources ◽  
List Type ◽  
Type Number ◽  
Radio Flux ◽  
Powerful Radio ◽  
Microwave Background ◽  
Microwave Background Radiation

The topic that I have to introduce today is concerned with the question as to whether or not we can obtain any cosmological information from radio astronomy. Alternatively, we may ask “Where does radio astronomy have an impact on cosmology?” There are several areas that must be discussed. They are: 1)The discovery and interpretation of the microwave background radiation.2)The identification of powerful radio sources and the discovery that many of them have large redshifts. If we can prove that the large redshifts mean that the objects are at great distances, then we can use these radio sources as follows:(a)We can attempt to obtain a Hubble relation for the optical objects which are identified with radio galaxies;(b)We can look for a relation between the angular diameters of the radio sources and the redshifts of the optically identified objects and we can also look at relations between the angular diameter and the radio flux;(c)We can construct log N - log S curves and we can carry out luminosity volume tests.

scholarly journals INFLATION, QUANTUM FIELDS, AND CMB ANISOTROPIES

2009 ◽  
Vol 18 (14) ◽  
pp. 2329-2335 ◽  
Author(s):  
IVÁN AGULLÓ ◽  
JOSÉ NAVARRO-SALAS ◽  
GONZALO J. OLMO ◽  
LEONARD PARKER
Keyword(s):  
Cosmic Microwave Background ◽  
Gravitational Waves ◽  
Early Universe ◽  
Inflationary Cosmology ◽  
Quantum Field ◽  
Quantum Fields ◽  
Microwave Background ◽  
Cosmological Inflation ◽  
Near Future ◽  
Field Renormalization

Inflationary cosmology has proven to be the most successful at predicting the properties of the anisotropies observed in the cosmic microwave background (CMB). In this essay we show that quantum field renormalization significantly influences the generation of primordial perturbations and hence the expected measurable imprint of cosmological inflation on the CMB. However, the new predictions remain in agreement with observation, and in fact favor the simplest forms of inflation. In the near future, observations of the influence of gravitational waves from the early universe on the CMB will test our new predictions.

scholarly journals The cosmic distance scale and H0: Past, present, and future

2012 ◽  
Vol 8 (S289) ◽  
pp. 3-9 ◽  
Author(s):  
Wendy L. Freedman
Keyword(s):  
Recent Progress ◽  
Hubble Space Telescope ◽  
Cosmological Parameters ◽  
Hubble Constant ◽  
Future Prospects ◽  
Microwave Background ◽  
A Value ◽  
Systematic Uncertainties ◽  
Near Future ◽  
The Universe

AbstractTwenty years ago, there was disagreement at a level of a factor of two as regards the value of the expansion rate of the Universe. Ten years ago, a value that was good to 10% was established using the Hubble Space Telescope (HST), completing one of the primary missions that NASA designed and built the HST to undertake. Today, after confronting most of the systematic uncertainties listed at the end of the Key Project, we are looking at a value of the Hubble constant that is plausibly known to within 3%. In the near future, an independently determined value of H0 good to 1% is desirable to constrain the extraction of other cosmological parameters from the power spectrum of the cosmic microwave background in defining a concordance model of cosmology. We review recent progress and assess the future prospects for those tighter constraints on the Hubble constant, which were unimaginable just a decade ago.

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