REVIEW 3 cited by
On the Size of a Black Hole: The Schwarzschild is the Biggest
Not yet reviewed by Pith; the record is open.
This paper has not been read by Pith yet. Machine review is queued; the pith claim, tier, and objections will appear here once it completes.
SPECIMEN: schema-true, not a live event
T0 review · schema-true
One-sentence machine reading of the paper's core claim.
pith:XXXXXXXX · record.json · timestamp
abstract
We consider static black holes in Einstein gravity and study parameters characterizing the black hole size, namely the radii of the horizon $R_+$, photon sphere $R_{\rm ph}$ and black hole shadow $R_{\rm sh}$. We find a sequence of inequalities $\frac32 R_+\, \le\, R_{\rm ph}\, \le \,\frac{1}{\sqrt3} R_{\rm sh}\,\le\, 3 M$, where $M$ is the black hole mass. These are consistent with and beyond the previously known upper bounds in literature. The Schwarzschild black hole saturates all the inequalities, making it the biggest of all for given mass. The inequalities include an upper bound of entropy for any quantum system with given energy. We also point out that some black holes satisfying the dominant energy condition can trap photons to form a stable photon shield outside the event horizon, but the shadow hides it from an observer at infinity.
Forward citations
Cited by 3 Pith papers
-
Bounds on the radius of outermost photon sphere and black hole shadow in $n$-dimensional Einstein gravity
Proves model-independent lower bound r_sh ≥ ((n-1)/2)^{1/(n-3)} sqrt((n-1)/(n-3)) r_H under WEC and upper bound r_sh ≤ sqrt((n-1)/(n-3)) [(n-1)M]^{1/(n-3)} under WEC+SEC+decay for nD black holes.
-
Static spheres in black hole spacetimes: pairing, energy conditions, and an upper bound on the innermost radius
Static spheres around black holes come in unstable/stable pairs, need negative radial pressure, and their innermost radius obeys a new upper bound tied to strong-energy-condition violation.
-
The existence and upper bound for stable photon spheres in static spherically symmetric black holes
For static spherical black holes with monotone m(r)/r^3, every stable photon sphere obeys r < 6M.
Discussion (0). Sign in to comment.