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Article

Perspectives on Constraining a Cosmological Constant-Type Parameter with Pulsar Timing in the Galactic Center

Ministero dell’Istruzione, dell’Università e della Ricerca (M.I.U.R.)-Istruzione, Viale Unità di Italia 68, 70125 Bari (BA), Italy
Universe 2018, 4(4), 59; https://doi.org/10.3390/universe4040059
Received: 19 February 2018 / Revised: 18 March 2018 / Accepted: 19 March 2018 / Published: 26 March 2018
(This article belongs to the Special Issue Universe: Feature Papers 2018 - Gravitational Physics)
Independent tests aiming to constrain the value of the cosmological constant Λ are usually difficult because of its extreme smallness ( Λ 1 × 10 - 52 m - 2 , or 2 . 89 × 10 - 122 in Planck units ) . Bounds on it from Solar System orbital motions determined with spacecraft tracking are currently at the 10 - 43 10 - 44 m - 2 ( 5 1 × 10 - 113 in Planck units ) level, but they may turn out to be optimistic since Λ has not yet been explicitly modeled in the planetary data reductions. Accurate ( σ τ p 1 10 μ s ) timing of expected pulsars orbiting the Black Hole at the Galactic Center, preferably along highly eccentric and wide orbits, might, at least in principle, improve the planetary constraints by several orders of magnitude. By looking at the average time shift per orbit Δ δ τ ¯ p Λ , an S2-like orbital configuration with e = 0 . 8839 , P b = 16 yr would permit a preliminarily upper bound of the order of Λ 9 × 10 - 47 m - 2 2 × 10 - 116 in Planck units if only σ τ p were to be considered. Our results can be easily extended to modified models of gravity using Λ -type parameters. View Full-Text
Keywords: astrophysical studies of gravity; general relativity; cosmological constant; neutron stars & pulsars; classical black holes astrophysical studies of gravity; general relativity; cosmological constant; neutron stars & pulsars; classical black holes
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MDPI and ACS Style

Iorio, L. Perspectives on Constraining a Cosmological Constant-Type Parameter with Pulsar Timing in the Galactic Center. Universe 2018, 4, 59. https://doi.org/10.3390/universe4040059

AMA Style

Iorio L. Perspectives on Constraining a Cosmological Constant-Type Parameter with Pulsar Timing in the Galactic Center. Universe. 2018; 4(4):59. https://doi.org/10.3390/universe4040059

Chicago/Turabian Style

Iorio, Lorenzo. 2018. "Perspectives on Constraining a Cosmological Constant-Type Parameter with Pulsar Timing in the Galactic Center" Universe 4, no. 4: 59. https://doi.org/10.3390/universe4040059

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