Craig Rudick - Diffuse Light Simulations

Craig Rudick
homepage

Diffuse Light Simulations

I am working with Chris Mihos, using numerical simulations to study low surface brightness, diffuse light in galaxy clusters, which is known as intra-cluster light or just ICL. Cameron McBride was responsible for a lot of the early work that got this project started.

Below you can find much of our work on analyzing the changes in the surface brightness distribution of the luminosity in the cluster as a function of time. We are currently working on analyzing observable kinematic structures in the ICL. Also, we are working on some more simulations to explore how cluster mass effects the ICL evolution.

Simulated Images and Movies

Currently, we have simulated three different galaxy clusters, each with a mass of approximately 10¹⁴ solar masses. The links below show some images of the simulated clusters. The images have been calibrated in surface brightness units of magnitudes per square arcsecond. There is a key at the bottom of each image: black represents all pixels brighter than 26 mag/sq.arcsec, red is 26.0-27.0 mag/sq.arcsec, etc. In all analyses we use an observational definition of ICL: luminosity fainter than (surface brighter greater than) 26.5 mag/sq.arcsec.

Our most interesting result is that the production of ICL is highly correlated with small scale accretion and merger events between groups within the cluster. All the information is really in the "delta_movie" files (aka the "karaoke" movies). On the right there are two plots. The top plot is simply the fraction of the total cluster luminoisty at ICL surface brightness. The bottom plot is the fractional change in ICL luminosity fraction per unit time - basically the derrivative of the top plot. The little red ball bounces along the plots so you can follow along at home!

Cluster C1    z=2.00   z=1.51   z=1.01   z=0.50   z=0.00   movie(mpeg)-big   movie(mpeg)-small   delta_movie(mpeg)
Cluster C2    z=2.00   z=1.51   z=1.01   z=0.50   z=0.00   movie(mpeg)-big   movie(mpeg)-small   delta_movie(mpeg)
Cluster C3    z=2.00   z=1.51   z=1.01   z=0.50   z=0.00   movie(mpeg)-big   movie(mpeg)-small   delta_movie(mpeg)

Tips for watching the movies:
The movies can be a bit buggy. One of these days I will get myself some better mpeg-making software. Until then...
Try the big versions first. If they give you trouble, use the small versions. Better hardware often helps, but of course we can't always control that. Also, the small versions are missing the color key at the bottom - I am working on that (but don't hold your breath waiting).
Linux: I recommend mpeg_play -dither color. The "-dither color" options are not absolutely essential, but without it you will not get the correct colors. mtv also should work. If you have another mpeg player you particularly like, I'd like to know.
Windows/Mac OSX:Windows Media Player or Quicktime should be fine. If they are acting up, sometimes trying different software helps.

Talks

Since most of my talks on this subject involve quite a few movies, which don't really transfer to PDF's, with each talk I have put up links to the movies for your viewing pleasure.

Santiago, Chile: ESO Groups of Galaxies in the Nearby Universe workshop, 12/07/2005. Simulating the Production of ICL in Galaxy Groups and Clusters (pdf)
Here is the corresponding paper for the conference proceedings.
This was short talk I gave at Cerca (the Case Physics department's weekly particle/astro lunch) which is an introduction to using Planetary Nebulae as Tracers of Intracluster Light .

Some of Chris's talks give a bit more background on ICL in general, including both observations and modelling.

Papers

The Formation and Evolution of Intracluster Light (PDF) . Accepted to ApJ. The first published paper on these simulations, examining how the surface brightness distribution of the clusters evolves.

Created by Craig Rudick, 2005.
Last modified 05/23/06.