Galactic-center S-Stars as a prospective test of the Einstein Equivalence Principle

Abstract

The S-Stars in the Galactic-center region are found to be on near-perfect Keplerian orbits around presumably a supermassive black hole, with periods of 15-50 yr. Since these stars reach a few percent of light speed at pericenter, various relativistic effects are expected, and have been discussed in the literature. We argue that an elegant test of the Einstein equivalence principle should be possible with existing instruments, through spectroscopic monitoring of an S-star concentrated during the months around pericenter, supplemented with an already-adequate astrometric determination of the inclination. In essence, the spectrum of an S-star can be considered a heterogeneous ensemble of clocks in a freely-falling frame, which near pericenter is moving at relativistic speeds.

4 pages, 2 figures, accepted for publication in Astrophysical Journal Letters

References in corpus (3)

• Testing the general relativistic ''no-hair'' theorems using the galactic center black hole SgrA*
• On the nature of the fast moving star S2 in the Galactic Center
• On post-Newtonian orbits and the Galactic-center stars

Cited by in corpus (19)

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• Perturbed stellar motions around the rotating black hole in Sgr A* for a generic orientation of its spin axis
• General relativistic effects on the orbit of the S2 star with GRAVITY
• Galactic Center Research: Manifestations of the Central Black Hole
• Testing the black hole no-hair theorem at the galactic center: Perturbing effects of stars in the surrounding cluster
• Investigating the Binarity of S0-2: Implications for its Origins and Robustness as a Probe of the Laws of Gravity around a Supermassive Black Hole
• On Testing the Kerr Metric of the Massive Black Hole in the Galactic Center via Stellar Orbital Motion: Full General Relativistic Treatment
• Free motion around black holes with discs or rings: between integrability and chaos - III
• Test of Einstein equivalence principle near the Galactic center supermassive black hole
• Prospects for constraining the spin of the massive black hole at the Galactic center via the relativistic motion of a surrounding star
• Probing the spinning of the massive black hole in the Galactic Center via pulsar timing: A Full Relativistic Treatment
• Clocks around Sgr A*
• On the Newtonian and Spin-induced Perturbations felt by the Stars Orbiting around the Massive Black Hole in the Galactic Center
• On the post-Keplerian corrections to the orbital periods of a two-body system and their application to the Galactic Center
• New test on the Einstein equivalence principle through the photon ring of black holes
• 3D Kinematics of Stellar SiO Masers in the Galactic Center