Black Holes

Cygnus X-I: Very much like classical binary.

No pulsing

Submilisecond flaring – auto correction function

One difference: wind fed

Something has to happen at M>2.1 Msun. No other known force after neutron degeneracy collapse forever. SNR or WD, NS exceeds mass limit therefore collapse

for light m=p/c

R is Schwarzshild Radius

No information within this radius can escape

Singularity is formed: Event horizon

We can watch stuff fall in, to fall in takes forever.




Angular Momentum

All other information lost forever

They have no magnetic field. They do not pulse

Black holes have no hair

How can we observe them? Put one in a binary system (as seen above)

Accretion disk emits x-rays

Orbital time ~ R/c

Cygnus X-1 is the only black hole we are resonalbly certain of.

No upper limit on mass – can grow forever.

Quasars (we think) form when enough mass is pulled into hole ~1-^ Msun

Things are tidally disrupted and then swallowed. There may be one in our galaxy.


Thermal Radiation

pair production at singularity

Blackbody radiation

Lose mass – become lighter

Burst or gamma rays not detected.

Could have formed these in the early universe – Primordial Black Holes


Gravitational Waves

Birth ripple of a forming black hole – detectors are being built