SIMBAD references

2017MNRAS.472.2249I - Mon. Not. R. Astron. Soc., 472, 2249-2262 (2017)

Post-Keplerian effects on radial velocity in binary systems and the possibility of measuring General Relativity with the star S2 in 2018.


Abstract (from CDS):

One of the directly measured quantities used in monitoring the orbits of many of the S stars revolving around the supermassive black hole (SMBH) in the Galactic center (GC) is their radial velocity (RV) V obtained with near-infrared spectroscopy. Here, we devise a general approach to calculate both the instantaneous variations DV(t) and the net shifts per revolution <DV> induced on such an observable by some post-Keplerian (pK) accelerations. In particular, we look at the general relativistic Schwarzschild (gravitoelectric) and Lense-Thirring (gravitomagnetic frame-dragging) effects, and the mass quadrupole. It turns out that we may be on the verge of measuring the Schwarzschild-type 1pN static component of the SMBH's field with the star S2 for which RV measurements accurate to about ≃ 30 - 50 km s–1 dating back to t0 = 2003.271 are currently available, and whose orbital period amounts to Pb = 16 yr. Indeed, while its expected general relativistic RV net shift per orbit amounts to just <DVGE> = -11.6 km s–1, it should reach a peak value as large as D VmaxGE(t_max) = 551 km s^{-1} at tmax = 2018.35. Current uncertainties in the S2 and SMBH's estimated parameters yield a variation range from 505 km s–1(2018.79) to 575 km s–1(2018.45). The periastron shift DoGE of S2 over the same time span will not be larger than 0.2 deg, while the current accuracy in estimating such an orbital element for this star is of the order of 0.6 deg. The frame-dragging and quadrupole-induced RV shifts are far smaller for S2, amounting to, at most, 0.19 km s–1, 0.0039 km s–1, respectively.

Abstract Copyright: 2017 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society

Journal keyword(s): gravitation - celestial mechanics - binaries: general - pulsars: general

Simbad objects: 7

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