http://arxiv.org/abs/2210.02164
We revisit the classic system of a spherically symmetric black hole in general relativity (i.e., a Schwarzschild black hole) surrounded by a geometrically thin accretion disk. Our purpose is to examine whether one can determine three parameters of this system (i.e., black hole mass $M$; distance between the black hole and an observer $r_o$; inclination angle $i$) solely by observing the accretion disk and the black-hole shadow. A point in our analysis is to allow $r_o$ to be finite, which is set to be infinite in most relevant studies. First, it is shown that one can determine the values of $(r_o/M, i)$, where $M/r_o$ is the so-called angular gravitational radius, from the size and shape of shadow. Then, it is shown that if one additionally knows the accretion rate $\dot{M}$ (resp.\ mass $M$) by any independent theoretical or observational approach, one can determine the values of $(M, r_o, i)$ [resp.\ $(\dot{M}, r_o, i)$] without degeneracy, in principle, from the value of flux at any point on the accretion disk.
K. Hioki and U. Miyamoto
Thu, 6 Oct 22
13/77
Comments: 25 pages, 11 figures
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