Workshop "Cosmology with Small Scale Structure" Jul 22-26, 2013

Workshop "Cosmology with Small Scale Structure"

Informal workshop to discuss cosmological constraints from the full predictions of clustering of galaxies and matter including scales within dark matter halos. The workshop will be focused on tests that use e.g. galaxy-galaxy correlation, cluster-galaxy cross-correlation, cluster-mass cross-correlation, redshift-space correlation function, marginalized over the galaxy-halo connection, to constrain cosmological parameters. We intend a working workshop, with discussions and active testing, and a few formal presentations.

major topics

  • accuracy of theoretical models for galaxy-galaxy and galaxy-mass correlations
  • discuss and compare various statistics, e.g. xi_clg (cluster-galaxy cross-correlation (or M/N)), xi_clm (cluster-mass cross-correlation), xi_gg(\sigma,\pi) (redshift-space correlation function)
  • theoretical uncertanties: which dominate and how can they be reduced?
  • observational uncertanties: which dominate and how can they be reduced?
  • is it really robust and competitive? how do we convince ourselves and others?


July 22 (Mon) - 26 (Fri), 2013


Conference room AB, Kavli IPMU, the University of Tokyo **The room was changed!**


  • Alexie Leauthaud (Kavli IPMU)
  • Surhud More (Kavli IPMU)
  • Masahiro Takada (Kavli IPMU)


  •  Martin White
  •  Frank van den Bosch
  •  Kazuya Koyama
  •  Jeremy Tinker
  •  Andreas Berlind
  • - and others …


Monday 22


Small-scale statistics

  • state of the art for various statistics: xi_gg, xi_gm, xi(rp, pi), M/N 
  • systematics for theoretical formulation
  • systematics for practical implementation on e.g. des, lsst
  • systematics in numerical simulations
  • should we invent new statistics? 


MODERATORS : Risa / Jeremy / Frank


Time  Discussion leaders Topic & key questions
9:30 Risa  Big Picture.  
10  Alexie  Quick summary of discussion from last meeting
12 - 1 lunch  
1 - 2  


Open discussion and work time     


Tuesday 23



  • How accurately do we now know the ingredients that go into analytic halo-type models:  mass function, halo clustering, halo structure?
    • What are the systematic errors due to ICs, N-body codes, resolution, box size?
    • What are the systematic errors due to halo-finding algorithms?  Does it matter what halo definition we use?
    • What are the systematic errors due to not including baryons?  Can we easily account for the effect of baryons without running gas simulations?
    • How "universal" are these properties (mass function, etc), i.e., what is the error in using an analytic function for a given cosmological model, when it was derived using a different cosmology?
  • Do we understand assembly bias well enough to account for it in our modeling?
  • Is it better to bypass these halo properties and measure galaxy statistics directly by populating simulations?  What are the systematic errors on statistics like the correlation function from all the items listed above?
  • Can we get away with approximating different cosmological models by intelligently rescaling a small number of boxes?  What are the errors caused by this?  If we need to run many boxes to cover the cosmological parameter space, can we interpolate to make the problem tractable?  How should we interpolate?
  • The answers to all these questions will depend on the statistic and physical scale in question.  That is a lot of information to compile.  What of all this should we focus on? 


MODERATORS: Salman / Katrin / Andreas


Time  Discussion leader Topic & key questions
9:30 - 12 Salman/Katrin/Andreas  
12 - 1  lunch  
1- 1:30    
1:30 - 2    
2 - 2:30    


Wednesday 24


Redshift space distortions


MODERATORS: Martin / Masahiro / Jeremy


Time  Discussion leader Topic & key questions
9:30 -12 Martin / Masahiro / Jeremy   
   Jeremy challenges for boss/ challenges for elg surveys (hetdex, eboss, bigboss) 
12 - 1  lunch


1 - 2    


Thursday 25


Morning : Effects of baryons

Afternoon : modified gravity






Time  Discussion leader Topic & key questions
9:30 -12 Joop Schaye / Andrew Zentner   
12 - 1  lunch


1 - 3 Kazuya  Modified gravity


Friday 26


optical cluster finding

    • state-of-the art update (redmapper)
    • where will be by the end of DES?
    • which observational systematics can be informed by simulations?
    • applications to small-scale modeling, including lensing and M/N


MODERATORS : Eduardo / Andrew /


Time  Discussion leader Topic & key questions
9:30 Eduardo  State of the art of cluster finding
10 - 12 Eduardo / Andrew Wetzel  
12 - 1  lunch  
1- 2   Summary by Frank  
Open discussion and work time     



On-line registration form (Indico page) is available here

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