### black hole model

**(BH model, model black hole, model BH)**
(description of a BH using math or computation)

By **black hole model** (or **model black hole**), I refer to mathematical
structures or computer calculations demonstrating aspects of black holes.
Black holes vary only in mass, electric charge, and rotation
(no-hair theorem),
though interactions with other objects (black hole mergers, accretion disks)
can lead to modeling challenges.
Some principal mathematical models:

**Schwarzschild black hole** (aka **Schwarzschild object**) - a mathematical model of a black hole that is not rotating and has no charge.
**Reissner-Nordström black hole** (aka **Reissner-Nordström object**) - mathematical model including charge, i.e., a **charged black hole**.
**Kerr black hole** (aka **Kerr object**) - mathematical model including rotation.
**Kerr-Newman black hole** (aka **Kerr-Newman object**) - mathematical model including both rotation and charge.

All four of these are exact according to general relativity (GR) and the characteristics
they are designed to handle, but they grow more mathematically
challenging as they grow more general, and it is often useful to
approximate with a simpler model from this list if charge or rotation
are minor influences. In modeling observations or realistic
scenarios, the Kerr model is common. Charge is typically ignored
as unlikely to remain significant: the electric force assists
accretion of the opposite charge. Significant rotation is
considered common and the Schwarzschild model is often no more
than a gross approximation of an actual black hole.

Additional models have been developed, some being approximations
of the above, and others including additional factors or adjusting
GR rules to accommodate theoretical issues (such as the
black-hole information paradox) and/or observed phenomena.
The term **nonsingular black hole model** refers to one class of these
alternative models.

An **extremal black hole** is a black hole at a lower limit: at
the minimal mass possible given its charge and rotation, a concept
relevant to the latter three models. Theory has suggested that one
would be stable, i.e., it would not emit **Hawking radiation**.

(*black holes,models*)
**Further reading:**

http://en.wikipedia.org/wiki/Schwarzschild_metric

http://en.wikipedia.org/wiki/Kerr_metric

http://en.wikipedia.org/wiki/Reissner-Nordstrom_metric

http://en.wikipedia.org/wiki/Rotating_black_hole

**Referenced by pages:**

black-hole information paradox

black hole shadow

Kerr black hole

metric

no-hair theorem

Penrose process

Index