Strong-field tests of gravity using pulsars and black holes

Krämer, M.; Backer, D. C.; Cordes, J. M.; Lazio, T. Joseph W.; Stappers, B. W.; Johnston, S.

doi:10.1016/j.newar.2004.09.020

Cited by 195 publications

(190 citation statements)

References 33 publications

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“…In particular, at long wavelengths, cosmic-microwave-background (CMB) experiments [1,2,3,4,5,6,7,8,9,10,11,12,13] will measure (or tightly constrain) the so-called tensor-to-scalar ratio r by searching for its characteristic "B-mode" imprint in the CMB polarization anisotropy [14,15,16]. And on shorter wavelengths, various techniques -including pulsar-timing (PT) [17,18,19] and laser-interferometer (LI) experiments [20,21,22,23,24,25,26] -will measure or constrain the present-day gravitational-wave energy spectrum Ω gw 0 (f ). The coming decade is likely to see exciting progress in this area.…”

Section: Pacs Numbersmentioning

confidence: 99%

Relating gravitational wave constraints from primordial nucleosynthesis, pulsar timing, laser interferometers, and the CMB: Implications for the early universe

Boyle¹,

2008

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We derive a general master equation relating the gravitational-wave observables r and Ω gw 0 (f ); or the observables Ω gw 0 (f 1 ) and Ω gw 0 (f 2 ). Here r is the so-called "tensor-to-scalar ratio," which is constrained by cosmic-microwave-background (CMB) experiments; and Ω gw 0 (f ) is the energy spectrum of primordial gravitational-waves, which is constrained e.g. by pulsar-timing (PT) measurements, laser-interferometer (LI) experiments, and the standard Big Bang Nucleosynthesis (BBN) bound. Differentiating the master equation yields a new expression for the tilt d ln Ω gw 0 (f )/d ln f of the present-day gravitational-wave spectrum. The relationship between r and Ω gw 0 (f ) depends sensitively on the uncertain physics of the early universe, and we show that this uncertainty may be encapsulated (in a model-independent way) by two quantities:ŵ(f ) andn t (f ), wheren t (f ) is a certain logarithmic average over n t (k) (the primordial tensor spectral index); andŵ(f ) is a certain logarithmic average overw(a) (the effective equation-of-state parameter in the early universe, after horizon re-entry). Here the effective equation-of-state parameterw(a) is a combination of the ordinary equation-of-state parameter w(a) and the bulk viscosity ζ(a). Thus, by comparing observational constraints on r and Ω gw 0 (f ), one obtains (remarkably tight) constraints in the {ŵ(f ),n t (f )} plane. In particular, this is the best way to constrain (or detect) the presence of a "stiff" energy component (with w > 1/3) in the early universe, prior to BBN. (The discovery of such a component would be no more surprising than the discovery of a tiny cosmological constant at late times!) Finally, although most of our analysis does not assume inflation, we point out that if CMB experiments detect a non-zero value for r, then we will immediately obtain (as a free by-product) a new upper boundŵ < ∼ 0.55 on the logarithmically averaged effective equation-of-state parameter during the "primordial dark age" between the end of inflation and the start of BBN.

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Section: Pacs Numbersmentioning

confidence: 99%

Relating gravitational wave constraints from primordial nucleosynthesis, pulsar timing, laser interferometers, and the CMB: Implications for the early universe

Boyle¹,

2008

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“…The next step in radio telescope evolution will be the use of large numbers of low-cost receivers that are combined interferometrically. These telescopes, the Allen Telescope Array (Bower 2007), LOFAR (Röttgering 2003), MeerKAT (Jonas 2007), ASKAP (Johnston et al 2008) and the SKA (Kramer et al 2004), create new possibilities for pulsar research.…”

Section: Introductionmentioning

confidence: 99%

Finding pulsars with LOFAR

Leeuwen¹,

Stappers

2010

A&A

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We investigate the number and type of pulsars that will be discovered with the low-frequency radio telescope LOFAR. We consider different search strategies for the Galaxy, for globular clusters and for other galaxies. We show that a 25-day all-sky Galactic survey can find approximately 900 new pulsars, probing the local pulsar population to a deep luminosity limit. For targets of smaller angular size such as globular clusters and galaxies many LOFAR stations can be combined coherently, to make use of the full sensitivity. Searches of nearby northern-sky globular clusters can find new low luminosity millisecond pulsars. Giant pulses from Crab-like extragalactic pulsars can be detected out to over a Mpc.

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“…The planned Square Kilometre Array will vastly improve all of these tests, and furthermore has great potential for finding highly exotic systems such as pulsar-black-hole binaries, which would open new realms of gravitational exploration (Kramer et al 2004).…”

Section: Geodetic Precessionmentioning

confidence: 99%

Binary pulsars and tests of general relativity

Stairs¹

2009

Proc. IAU

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Abstract. Binary pulsars are a valuable laboratory for gravitational experiments. Doubleneutron-star systems such as the double pulsar provide the most stringent tests of strong-field gravity available to date, while pulsars with white-dwarf companions constrain departures from general relativity based on the difference in gravitational binding energies in the two stars.Future observations may open up entirely new tests of the predictions of general relativity.

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Strong-field tests of gravity using pulsars and black holes

Cited by 195 publications

References 33 publications

Relating gravitational wave constraints from primordial nucleosynthesis, pulsar timing, laser interferometers, and the CMB: Implications for the early universe

Relating gravitational wave constraints from primordial nucleosynthesis, pulsar timing, laser interferometers, and the CMB: Implications for the early universe

Finding pulsars with LOFAR

Binary pulsars and tests of general relativity

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