On the possible orbital motion of Sgr A* in the smooth potential of the Milky Way. (arXiv:2104.03229v1 [astro-ph.GA])

<a href="http://arxiv.org/find/astro-ph/1/au:+Nikiforov_I/0/1/0/all/0/1">Igor' I. Nikiforov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Veselova_A/0/1/0/all/0/1">Angelina V. Veselova</a>

The modern accuracy of measurements allows the residual/peculiar

(Galactocentric) velocity of the supermassive black hole (SMBH) in our Galaxy,

Sgr A*, on the order of several kilometers per second. We integrate possible

orbits of the SMBH along with the surrounding nuclear star cluster (NSC) for a

barred model of the Galaxy using modern constraints on the components of the

SMBH Galactocentric velocity. Is is shown that the range of oscillations of the

SMBH + NSC in a regular Galactic field in the plane of the Galaxy allowed by

these constraints strongly depends on the set of central components of the

Galactic potential. If the central components are represented only by a

bulge/bar, for a point estimate of the SMBH Galactocentric velocity, the

oscillation amplitude does not exceed 7 pc in the case that a classical bulge

is present and reaches 25 pc if there is no bulge; with SMBH velocity

components within the $2sigma$ significance level, the amplitude can reach 15

and 50 pc, respectively. However, when taking into account the nuclear stellar

disk (NSD), even in the absence of a bulge, the oscillation amplitude is only 5

pc for the point estimate of the SMBH velocity, and 10 pc for the $2sigma$

significance level. Thus, the possible oscillations of the SMBH + NSC complex

from the confirmed components of the Galaxy’s potential are mostly limited by

the NSD, and even taking into account the uncertainty of the mass of the

latter, the oscillation amplitude can hardly exceed $13,text{pc}=6’$.

The modern accuracy of measurements allows the residual/peculiar

(Galactocentric) velocity of the supermassive black hole (SMBH) in our Galaxy,

Sgr A*, on the order of several kilometers per second. We integrate possible

orbits of the SMBH along with the surrounding nuclear star cluster (NSC) for a

barred model of the Galaxy using modern constraints on the components of the

SMBH Galactocentric velocity. Is is shown that the range of oscillations of the

SMBH + NSC in a regular Galactic field in the plane of the Galaxy allowed by

these constraints strongly depends on the set of central components of the

Galactic potential. If the central components are represented only by a

bulge/bar, for a point estimate of the SMBH Galactocentric velocity, the

oscillation amplitude does not exceed 7 pc in the case that a classical bulge

is present and reaches 25 pc if there is no bulge; with SMBH velocity

components within the $2sigma$ significance level, the amplitude can reach 15

and 50 pc, respectively. However, when taking into account the nuclear stellar

disk (NSD), even in the absence of a bulge, the oscillation amplitude is only 5

pc for the point estimate of the SMBH velocity, and 10 pc for the $2sigma$

significance level. Thus, the possible oscillations of the SMBH + NSC complex

from the confirmed components of the Galaxy’s potential are mostly limited by

the NSD, and even taking into account the uncertainty of the mass of the

latter, the oscillation amplitude can hardly exceed $13,text{pc}=6’$.

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