Alexander Knebe, Frazer R. Pearce, Hanni Lux, Yago Ascasibar, Peter Behroozi, Javier Casado, Christine Corbett Moran, Juerg Diemand, Klaus Dolag, Rosa Dominguez-Tenreiro, Pascal Elahi, Bridget Falck, Stefan Gottloeber, Jiaxin Han, Anatoly Klypin, Zarija Lukic, Michal Maciejewski, Cameron K. McBride, Manuel E. Merchan, Stuart I. Muldrew, Mark Neyrinck, Julian Onions, Susana Planelles, Doug Potter, Vicent Quilis, Yann Rasera, Paul M. Ricker, Fabrice Roy, Andres N. Ruiz, Mario A. Sgro, Volker Springel, Joachim Stadel, P. M. Sutter, Dylan Tweed, Marcel Zemp
[abridged] The ever increasing size and complexity of data coming from simulations of cosmic structure formation demands equally sophisticated tools for their analysis. During the past decade, the art of object finding in these simulations has hence developed into an important discipline itself. A multitude of codes based upon a huge variety of methods and techniques have been spawned yet the question remained as to whether or not they will provide the same (physical) information about the structures of interest. This concern gave rise to a series of workshops and comparison papers of which we here present a brief summary. But we also go one step further and investigate in more detail the (possible) origin of any deviations across finders. To this extent we decipher and discuss differences in halo finding methods, clearly separating them from the disparity in definitions of halo properties. We observe that different codes not only find different numbers of objects leading to a scatter of up to 20 per cent in the halo mass and Vmax function, but also that the particulars of those objects that are identified by all finders differ. [...] We close with a discussion of the relevance and implications of the scatter across different codes for other fields such as semi-analytical galaxy formation models, gravitational lensing, and observables in general. In summary we conclude that while the majority of codes give results with a scatter below 1 per cent (at least for the most basic halo properties) once a particular definition has been specified, the residual differences for more complex quantities such as spin parameter are more sensitive to the particular implementation of the initial particle collection. We therefore caution any user of halo finders and their catalogues to not use the data blindly but to consider the mode of operation and definitions used during its generation.
View original:
http://arxiv.org/abs/1304.0585
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