Numerical Relativity and Data Analysis:
Nov 6-7, 2006 @ MIT, Boston

Navigation

Overview
Registration & Travel
Program
Organization
LSC Meeting

Mon 06 Nov 2006 08:15:15 AM CST

Ulrich Sperhake

Patrick asked about the outer boundary conditions.  Ulrich and Harald
reported that the effects of outer boundary conditions seem to be very
small in current simulations.  Outer boundaries are out at ~200 M and
above .......

Luis asked about extraction radius.  Ulrich commented that this does
not seem to cause a great deal of changes.  

Luis commented that the boundaries have to be put very far away.  With
AMR, only evolve outer regions very small amount.  

Bernard asked why the boundary needs to be out so far if the
extraction distance is much smaller.  Ulrich commented that this is
not so

Extraction radius needed to be in close because of under-resolved
area.

Lee mentioned that showing that numerical convergence does not
demonstrate correct answer.  Tests they did showed that there are big
dependences on the boundary conditions.   

Only way to really sort this out.  Put outer bounadry far enough that
there is no causal contact.  This is being done by a person at
Caltech.  Should be available in a month or two.  

Steve Fairhurst asked about the nature of the waveform.  There is
propagation speed.  1/r and speed of propagation = 1.  

Ed Seidel asked how much phase loss can the data analysis tolerate.
Ducnan reminded people that the match is the best way to talk about
the accuracy in the context of gravitational wave data analysis. 

Bernard commented that one way to put a number on it.  Mentioned that
there are template banks that have a fractional error.  

Peter Shawhan ...... 

Warren Anderson mentioned that there are two issues.  First is
detection,  but the second is measurement accuracy and how to do
science based on the simulations.  

Yuk Tung Liu presented some information about binary neutron stars,
gravitational waves and short gamma ray bursts.

Very rapid rotation -> Bar instability ......... 10-15Mpc.  High frequency
waves.

Peter Shawhan asked about the second GW burst ~ 10 ms to seconds ..... 

Patrick asked about the gamma ray burst generation. 

Warren asked how likely with realistic data, physics, to get to the
bar instability.  

Sukanta asked what are the remaining problems with initial data.
Ulrich responded that there is a lot of work remaining on this issue.
It will require a very careful comparison with pN.  

Denis Pollney added that there is a big question about eccentricity
and the dependence on initial data.  

Ed added that there is a lot of dependence on what the physics is.  

Harald mentioned that there he will show a slide this afternoon.  He
thinks the eccentricity is not too big and may not be a problem.  

Ulrich mentioned that simulations may circularize them.  Mark miller
commented time was too long for loss of eccentricity for numerical
relativity to make simulations.  

Josh Faber talked about binary neutron star and black hole mergers.  

  10 Msun or larger.  The NS is swallowed whole.  There will be a
  strong ringdown.  

  Smaller mas black hole 10-15Msun,  can get disruption.  

  Weak GW from NS remnant.  

  Stable mass transfer very unlikely.  

  Smaller black hole,  longer accretion phase.  About 1/10 Msun
  accretion disk.  

  Confidence of GRB production.  Geometry correct.  Disk gets very hot
  10^11 K.  But no mag fields to understand it in general.  

  Accretions disks last about ~ 100 ms and couple of secs

Steve Fairhurst asked why does the recall velocity only depend on eta?
........