28 - Black Holes

What is a black hole?

An object so dense that even light cannot escape it

What is the event horizon (also known as the Schwarzchild Radius)?

The distance within which, if light passes any closer, it will be captured

In 2019, a planet-wide telescope called the _____ _______ Telescope directly imaged the event horizon of M87’s SMBH, confirming GR predictions.

Event Horizon

What is the mass of a stellar black hole, and how are they formed?

1-1000 solar masses, from death of very massive star (more than 25 solar masses)

What is the mass of an intermediate mass black hole?

1000 to 100,000 solar masses

What is the mass of a supermassive black hole?

More than 100,000 solar masses, typically at the centres of galaxies

What black holes were made at Big Bang (speculative) and are generally super small?

Primordial black holes

What is the only known way to compress matter enough to make a BH?

Death of a super-massive star

Black holes pull matter in. The gas can radiate away energy, but retains ______ ________, forming a disk.

Angular momentum

Black holes are extremely hot and bright, reaching ____ or more.

10^8K

Black holes emit thermally in hard _____.

X-rays

What is the early seed problem?

Black holes of over 10^9 solar masses when the universe was less than a billion years old, which is not possible if starting from stellar seed

When a black hole is accreting, it will release energy and shine. This is an _____ ________ ________, also known as an ___.

Active Galactic Nucleus, AGN

What are the brightest AGN called, typically associated with galaxy mergers or ellipticals?

Quasars

What are modestly bright AGN called, more often in spirals?

Seyferts

Accretion disks have super-heated gas emitting energetic ________, such as _____ and __.

Photons, X-rays, UV

Gas and dust absorbs the photons emitted by the heated gas, and gets pushed into an _________ ____ ____.

Accretion disk wind

As matter falls in, it concentrates into a super-strong ________ _____. Charged particles like to flow along field lines, and are accelerated into a tightly ____________ beam called a ___, which can extend beyond the virial radius.

Magnetic field, collimated, jet

The black hole jets release ___________ radiation, which is broad-spectrum, not peaked at a particular frequency. Jets are prominent in the radio

Synchtron

What is AGN feedback?

The energy put out by AGN via winds and jets

What % of material in accretion disk falls in, with the rest being ejected?

10%

How much energy does a quasar put out per second (Joules)?

10^38 J