English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

Sagittarius A* (Sgr A*) is the central supermassive black hole with the mass$\sim 4\times 10^6 M_{\odot}$ in the Milky Way and stars are orbiting aroundit. In May 2018, one of the nearest stars to Sgr A* named S0-2/S2 experiencedthe pericenter passage. The redshift of photons from S0-2 had varied from$4000\>{\rm km\>s^{-1}}$ to $-2000\>{\rm km\>s^{-1}}$ during the pericenterpassage, which is within $0.5\>{\rm yr}$. In this paper, we show that thissteep variation of the redshift gives a strong constraint on a dark massdistribution inside the orbit of S0-2. By applying a simple $\chi^2$ analysisto the observed redshift, we can easily distinguish between the two models, thepoint mass model and the point mass plus an extended mass model without thebest-fitting parameter search. Our redshift data during the pericenter passagein 2018 with Subaru/IRCS bound the amount of the extended mass inside the orbitof S0-2 less than $0.5\,\%$ ($\sim 2 \times 10^4 M_\odot$) of the mass of SgrA*. This constraint obtained by our simple analysis is comparable to previousworks with the best-fitting parameter search to the motion of S0-2 includingthe effect of the extended mass. We consider both the power-law and the Plummermodels for the dark mass distribution model, but the significant differencebetween these results is not found.

Constraints on the dark mass distribution surrounding Sgr A*: simple $\chi^2$ analysis for the redshift of photons from orbiting stars