Who and what

I am a graduate student in the Astrophysics Department at U.C. Santa Cruz, and should be finishing my PhD work circa 2013.

If my work interests you, or if you have questions about my current research, feel free to contact me at:
lruhlen (at) ucsc (dot) edu.

Black holes: accretion + hysteresis

I use a combination of observations and computational models to find out how matter falls into black holes.


Accretion flows around black holes have several common components, shown in the illustration:

  1. An accretion disk, which produces lower-energy ("soft") x-rays.
  2. A corona, which produces higher-energy ("hard") x-rays.
  3. Sometimes, jets (not pictured here). These produce synchrotron radio emission. If or when they hit regions of denser gas, they can also produce visible light.

My own work looks at the hysteresis phenomenon.
In hysteretic black hole systems, both hard and soft spectra can give rise to the same overall luminosities. Since differnt parts of the accretion flow produce different spectra, the hysteresis phenomenon gives us a way to 'see' how different parts of the flow behave.