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Galactic-center S stars as a prospective test of the Einstein equivalence principle


Angélil, R; Saha, P (2011). Galactic-center S stars as a prospective test of the Einstein equivalence principle. Astrophysical Journal Letters, 734(1):L19.

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.

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.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute for Computational Science
Dewey Decimal Classification:530 Physics
Language:English
Date:June 2011
Deposited On:18 Feb 2012 14:17
Last Modified:05 Apr 2016 14:55
Publisher:Institute of Physics Publishing
ISSN:0004-637X (P) 1538-4357 (E)
Publisher DOI:https://doi.org/10.1088/2041-8205/734/1/L19
Related URLs:http://arxiv.org/abs/1105.0918

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