Haloes gone MAD ★ : The Halo‐Finder Comparison Project
dc.contributor.author | Knebe, Alexander | en_US |
dc.contributor.author | Knollmann, Steffen R. | en_US |
dc.contributor.author | Muldrew, Stuart I. | en_US |
dc.contributor.author | Pearce, Frazer R. | en_US |
dc.contributor.author | Aragon‐calvo, Miguel Angel | en_US |
dc.contributor.author | Ascasibar, Yago | en_US |
dc.contributor.author | Behroozi, Peter S. | en_US |
dc.contributor.author | Ceverino, Daniel | en_US |
dc.contributor.author | Colombi, Stephane | en_US |
dc.contributor.author | Diemand, Juerg | en_US |
dc.contributor.author | Dolag, Klaus | en_US |
dc.contributor.author | Falck, Bridget L. | en_US |
dc.contributor.author | Fasel, Patricia | en_US |
dc.contributor.author | Gardner, Jeff | en_US |
dc.contributor.author | Gottlöber, Stefan | en_US |
dc.contributor.author | Hsu, Chung-hsing | en_US |
dc.contributor.author | Iannuzzi, Francesca | en_US |
dc.contributor.author | Klypin, Anatoly | en_US |
dc.contributor.author | Lukić, Zarija | en_US |
dc.contributor.author | Maciejewski, Michal | en_US |
dc.contributor.author | McBride, Cameron | en_US |
dc.contributor.author | Neyrinck, Mark C. | en_US |
dc.contributor.author | Planelles, Susana | en_US |
dc.contributor.author | Potter, Doug | en_US |
dc.contributor.author | Quilis, Vicent | en_US |
dc.contributor.author | Rasera, Yann | en_US |
dc.contributor.author | Read, Justin I. | en_US |
dc.contributor.author | Ricker, Paul M. | en_US |
dc.contributor.author | Roy, Fabrice | en_US |
dc.contributor.author | Springel, Volker | en_US |
dc.contributor.author | Stadel, Joachim | en_US |
dc.contributor.author | Stinson, Greg C. | en_US |
dc.contributor.author | Sutter, P. M. | en_US |
dc.contributor.author | Turchaninov, Victor | en_US |
dc.contributor.author | Tweed, Dylan | en_US |
dc.contributor.author | Yepes, Gustavo | en_US |
dc.contributor.author | Zemp, Marcel | en_US |
dc.date.accessioned | 2011-11-10T15:39:46Z | |
dc.date.available | 2012-10-01T18:34:51Z | en_US |
dc.date.issued | 2011-08-11 | en_US |
dc.identifier.citation | Knebe, Alexander; Knollmann, Steffen R.; Muldrew, Stuart I.; Pearce, Frazer R.; Aragon‐calvo, Miguel Angel ; Ascasibar, Yago; Behroozi, Peter S.; Ceverino, Daniel; Colombi, Stephane; Diemand, Juerg; Dolag, Klaus; Falck, Bridget L.; Fasel, Patricia; Gardner, Jeff; Gottlöber, Stefan ; Hsu, Chung‐hsing ; Iannuzzi, Francesca; Klypin, Anatoly; Lukić, Zarija ; Maciejewski, Michal; McBride, Cameron; Neyrinck, Mark C.; Planelles, Susana; Potter, Doug; Quilis, Vicent; Rasera, Yann; Read, Justin I.; Ricker, Paul M.; Roy, Fabrice; Springel, Volker; Stadel, Joachim; Stinson, Greg; Sutter, P. M.; Turchaninov, Victor; Tweed, Dylan; Yepes, Gustavo; Zemp, Marcel (2011). "Haloes gone MAD â : The Haloâ Finder Comparison Project." Monthly Notices of the Royal Astronomical Society 415(3). <http://hdl.handle.net/2027.42/87161> | en_US |
dc.identifier.issn | 0035-8711 | en_US |
dc.identifier.issn | 1365-2966 | en_US |
dc.identifier.uri | https://hdl.handle.net/2027.42/87161 | |
dc.description.abstract | We present a detailed comparison of fundamental dark matter halo properties retrieved by a substantial number of different halo finders. These codes span a wide range of techniques including friends‐of‐friends, spherical‐overdensity and phase‐space‐based algorithms. We further introduce a robust (and publicly available) suite of test scenarios that allow halo finder developers to compare the performance of their codes against those presented here. This set includes mock haloes containing various levels and distributions of substructure at a range of resolutions as well as a cosmological simulation of the large‐scale structure of the universe. All the halo‐finding codes tested could successfully recover the spatial location of our mock haloes. They further returned lists of particles (potentially) belonging to the object that led to coinciding values for the maximum of the circular velocity profile and the radius where it is reached. All the finders based in configuration space struggled to recover substructure that was located close to the centre of the host halo, and the radial dependence of the mass recovered varies from finder to finder. Those finders based in phase space could resolve central substructure although they found difficulties in accurately recovering its properties. Through a resolution study we found that most of the finders could not reliably recover substructure containing fewer than 30–40 particles. However, also here the phase‐space finders excelled by resolving substructure down to 10–20 particles. By comparing the halo finders using a high‐resolution cosmological volume, we found that they agree remarkably well on fundamental properties of astrophysical significance (e.g. mass, position, velocity and peak of the rotation curve). We further suggest to utilize the peak of the rotation curve, v max , as a proxy for mass, given the arbitrariness in defining a proper halo edge. | en_US |
dc.publisher | Blackwell Publishing Ltd | en_US |
dc.publisher | Wiley Periodicals, Inc. | en_US |
dc.subject.other | Methods: Numerical | en_US |
dc.subject.other | Galaxies: Evolution | en_US |
dc.subject.other | Galaxies: Haloes | en_US |
dc.subject.other | Cosmology: Miscellaneous | en_US |
dc.subject.other | Cosmology: Theory | en_US |
dc.subject.other | Dark Matter | en_US |
dc.title | Haloes gone MAD ★ : The Halo‐Finder Comparison Project | en_US |
dc.type | Article | en_US |
dc.rights.robots | IndexNoFollow | en_US |
dc.subject.hlbsecondlevel | Astronomy | en_US |
dc.subject.hlbtoplevel | Science | en_US |
dc.description.peerreviewed | Peer Reviewed | en_US |
dc.contributor.affiliationum | Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109‐1042, USA | en_US |
dc.contributor.affiliationother | Departamento de Física Teórica, Módulo C‐15, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Cantoblanco, Madrid, Spain | en_US |
dc.contributor.affiliationother | School of Physics & Astronomy, University of Nottingham, Nottingham NG7 2RD | en_US |
dc.contributor.affiliationother | Department of Physics and Astronomy, Johns Hopkins University, 3701 San Martin Drive, Baltimore, MD 21218, USA | en_US |
dc.contributor.affiliationother | Kavli Institute for Particle Astrophysics and Cosmology, Stanford, CA 94309, USA | en_US |
dc.contributor.affiliationother | Physics Department, Stanford University, Stanford, CA 94305, USA | en_US |
dc.contributor.affiliationother | SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA | en_US |
dc.contributor.affiliationother | Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel | en_US |
dc.contributor.affiliationother | Institut d’Astrophysique de Paris, CNRS UMR 7095 and UPMC, 98bis, bd Arago, F‐75014 Paris, France | en_US |
dc.contributor.affiliationother | Institute for Theoretical Physics, University of Zurich, Winterthurerstrasse 190, CH‐8057 Zurich, Switzerland | en_US |
dc.contributor.affiliationother | Max‐Planck Institut für Astrophysik, Karl‐Schwarzschild Str. 1, D‐85741 Garching, Germany | en_US |
dc.contributor.affiliationother | CCS‐3, Computer, Computational and Statistical Sciences Division, Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87544, USA | en_US |
dc.contributor.affiliationother | Department of Physics, University of Washington, PO Box 351560, Seattle, WA 98195, USA | en_US |
dc.contributor.affiliationother | Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany | en_US |
dc.contributor.affiliationother | Computer Science and Mathematics Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA | en_US |
dc.contributor.affiliationother | Department of Astronomy, New Mexico State University, Las Cruces, NM 88003‐0001, USA | en_US |
dc.contributor.affiliationother | T‐2, Theoretical Division, Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87544, USA | en_US |
dc.contributor.affiliationother | Department of Physics & Astronomy, Vanderbilt University, 6301 Stevenson Center, Nashville, TN 37235, USA | en_US |
dc.contributor.affiliationother | Departament d’Astronomia i Astrofísica, Universitat de València, 46100 ‐ Burjassot (Valencia), Spain | en_US |
dc.contributor.affiliationother | CNRS, Laboratoire Univers et Théories (LUTh), UMR 8102 CNRS, Observatoire de Paris, Université Paris Diderot, 5 Place Jules Janssen, 92190 Meudon, France | en_US |
dc.contributor.affiliationother | Institute for Astronomy, Department of Physics, ETH Zürich, Wolfgang‐Pauli‐Strasse 16, CH‐8093 Zürich, Switzerland | en_US |
dc.contributor.affiliationother | Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH | en_US |
dc.contributor.affiliationother | Department of Physics, University of Illinois at Urbana‐Champaign, Urbana, IL 61801‐3080, USA | en_US |
dc.contributor.affiliationother | National Center for Supercomputing Applications, University of Illinois at Urbana‐Champaign, Urbana, IL 61801, USA | en_US |
dc.contributor.affiliationother | Heidelberg Institute for Theoretical Studies, Schloss‐Wolfsbrunnenweg 35, 69118 Heidelberg, Germany | en_US |
dc.contributor.affiliationother | Zentrum für Astronomie der Universität Heidelberg, ARI, Mönchhofstr. 12‐14, 69120 Heidelberg, Germany | en_US |
dc.contributor.affiliationother | Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE | en_US |
dc.contributor.affiliationother | Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, 125047 Moscow, Russia | en_US |
dc.contributor.affiliationother | Institut d’Astrophysique Spatiale, CNRS/Universite Paris‐Sud 11, 91405 Orsay, France | en_US |
dc.description.bitstreamurl | http://deepblue.lib.umich.edu/bitstream/2027.42/87161/1/j.1365-2966.2011.18858.x.pdf | |
dc.identifier.doi | 10.1111/j.1365-2966.2011.18858.x | en_US |
dc.identifier.source | Monthly Notices of the Royal Astronomical Society | en_US |
dc.identifier.citedreference | Agertz O. et al., 2007, MNRAS, 380, 963 | en_US |
dc.identifier.citedreference | Ascasibar Y., Binney J., 2005, MNRAS, 356, 872 | en_US |
dc.identifier.citedreference | Ascasibar Y., Gottlöber S., 2008, MNRAS, 386, 2022 | en_US |
dc.identifier.citedreference | Aubert D., Pichon C., Colombi S., 2004, MNRAS, 352, 376 | en_US |
dc.identifier.citedreference | Bagla J. S., Khandai N., 2009, MNRAS, 396, 2211 | en_US |
dc.identifier.citedreference | Barnes J., Hut P., 1986, Nat, 324, 446 | en_US |
dc.identifier.citedreference | Bertschinger E., Gelb J. M., 1991, Comput. Phys., 5, 164 | en_US |
dc.identifier.citedreference | Binney J., Tremaine S., 1987, Galactic Dynamics. Princeton Univ. Press, Princeton, NJ | en_US |
dc.identifier.citedreference | Bode P., Ostriker J. P., Xu G., 2000, ApJS, 128, 561 | en_US |
dc.identifier.citedreference | Bullock J. S., Kolatt T. S., Sigad Y., Somerville R. S., Kravtsov A. V., Klypin A. A., Primack J. R., Dekel A., 2001, MNRAS, 321, 559 | en_US |
dc.identifier.citedreference | Cohn J. D., White M., 2008, MNRAS, 385, 2025 | en_US |
dc.identifier.citedreference | Couchman H. M. P., Thomas P. A., Pearce F. R., 1995, ApJ, 452, 797 | en_US |
dc.identifier.citedreference | Courtin J., Rasera Y., Alimi J., Corasaniti P., Boucher V., Füzfa A., 2011, MNRAS, 410, 1911 | en_US |
dc.identifier.citedreference | Davis M., Efstathiou G., Frenk C. S., White S. D. M., 1985, ApJ, 292, 371 | en_US |
dc.identifier.citedreference | Dekel A., Devor J., Hetzroni G., 2003, MNRAS, 341, 326 | en_US |
dc.identifier.citedreference | Diemand J., Kuhlen M., Madau P., 2006, ApJ, 649, 1 | en_US |
dc.identifier.citedreference | Doumler T., Knebe A., 2010, MNRAS, 403, 453 | en_US |
dc.identifier.citedreference | Dubinski J., Kim J., Park C., Humble R., 2004, New Astron., 9, 111 | en_US |
dc.identifier.citedreference | Eisenstein D. J., Hut P., 1998, ApJ, 498, 137 | en_US |
dc.identifier.citedreference | Frenk C. S. et al., 1999, ApJ, 525, 554 | en_US |
dc.identifier.citedreference | Fryxell B. et al., 2000, ApJS, 131, 273 | en_US |
dc.identifier.citedreference | Gardner J. P., Connolly A., McBride C., 2007a, Broadening Participation in the TeraGrid Enabling Knowledge Discovery in a Virtual Universe. ACM Press, Madison, WI | en_US |
dc.identifier.citedreference | Gardner J. P., Connolly A., McBride C., 2007b, Challenges of Large Applications in Distributed Environments (CLADE 2007) Enabling Rapid Development of Parallel Tree Search Applications. ACM Press, Monterey, CA | en_US |
dc.identifier.citedreference | Gelb J. M., 1992, PhD thesis, Massachusetts Institute of Technology | en_US |
dc.identifier.citedreference | Gelb J. M., Bertschinger E., 1994, ApJ, 436, 467 | en_US |
dc.identifier.citedreference | Gill S. P. D., Knebe A., Gibson B. K., 2004, MNRAS, 351, 399 | en_US |
dc.identifier.citedreference | Gnedin N. Y., 1995, ApJS, 97, 231 | en_US |
dc.identifier.citedreference | Gottlöber S., Yepes G., 2007, ApJ, 664, 117 | en_US |
dc.identifier.citedreference | Gottlöber S., Klypin A. A., Kravtsov A. V., 1999, in Giuricin G., Mezzetti M., Salucci P., eds, ASP Conf. Ser. Vol. 176, Observational Cosmology: The Development of Galaxy Systems. Astron. Soc. Pac., San Francisco, p. 418 | en_US |
dc.identifier.citedreference | Governato F., Moore B., Cen R., Stadel J., Lake G., Quinn T., 1997, Nat, 2, 91 | en_US |
dc.identifier.citedreference | Habib S. et al., 2009, J. Phys. Conf. Ser., 180, 012019 | en_US |
dc.identifier.citedreference | Hayashi E., Navarro J. F., Taylor J. E., Stadel J., Quinn T., 2003, ApJ, 584, 541 | en_US |
dc.identifier.citedreference | Heitmann K. et al., 2008, Comput. Sci. Discovery, 1, 015003 | en_US |
dc.identifier.citedreference | Hernquist L., 1990, ApJ, 356, 359 | en_US |
dc.identifier.citedreference | Hernquist L., 1993, ApJS, 86, 389 | en_US |
dc.identifier.citedreference | Jenkins A., Frenk C. S., White S. D. M., Colberg J. M., Cole S., Evrard A. E., Couchman H. M. P., Yoshida N., 2001, MNRAS, 321, 372 | en_US |
dc.identifier.citedreference | Kazantzidis S., Magorrian J., Moore B., 2004, ApJ, 601, 37 | en_US |
dc.identifier.citedreference | Kim J., Park C., 2006, ApJ, 639, 600 | en_US |
dc.identifier.citedreference | Klimentowski J., Łokas E. L., Kazantzidis S., Mayer L., Mamon G. A., 2009, MNRAS, 397, 2015 | en_US |
dc.identifier.citedreference | Klypin A., Holtzman J., 1997, preprint (arXiv e‐prints) | en_US |
dc.identifier.citedreference | Klypin A., Gottlöber S., Kravtsov A. V., Khokhlov A. M., 1999, ApJ, 516, 530 | en_US |
dc.identifier.citedreference | Knebe A., Kravtsov A. V., Gottlöber S., Klypin A. A., 2000, MNRAS, 317, 630 | en_US |
dc.identifier.citedreference | Knebe A., Green A., Binney J., 2001, MNRAS, 325, 845 | en_US |
dc.identifier.citedreference | Knollmann S. R., Knebe A., 2009, ApJS, 182, 608 | en_US |
dc.identifier.citedreference | Kravtsov A. V., Klypin A. A., Khokhlov A. M., 1997, ApJS, 111, 73 | en_US |
dc.identifier.citedreference | Kruskal Joseph B. J., 1956, Proc. Am. Math. Soc., 7, 48 | en_US |
dc.identifier.citedreference | Lacey C., Cole S., 1994, MNRAS, 271, 676 | en_US |
dc.identifier.citedreference | Łokas E. L., Mamon G. A., 2001, MNRAS, 321, 155 | en_US |
dc.identifier.citedreference | Lukić Z., Heitmann K., Habib S., Bashinsky S., Ricker P. M., 2007, ApJ, 671, 1160 | en_US |
dc.identifier.citedreference | Lukić Z., Reed D., Habib S., Heitmann K., 2009, ApJ, 692, 217 | en_US |
dc.identifier.citedreference | Lux H., Read J. I., Lake G., 2010, MNRAS, 406, 2312 | en_US |
dc.identifier.citedreference | Maciejewski M., Colombi S., Springel V., Alard C., Bouchet F. R., 2009, MNRAS, 396, 1329 | en_US |
dc.identifier.citedreference | Merz H., Pen U., Trac H., 2005, New Astron., 10, 393 | en_US |
dc.identifier.citedreference | More S., Kravtsov A., Dalal N., Gottlöber S., 2011, preprint (arXiv e‐prints) | en_US |
dc.identifier.citedreference | Muldrew S. I., Pearce F. R., Power C., 2011, MNRAS, 410, 2617 | en_US |
dc.identifier.citedreference | Navarro J. F., Frenk C. S., White S. D. M., 1995, MNRAS, 275, 720 | en_US |
dc.identifier.citedreference | Navarro J. F., Frenk C. S., White S. D. M., 1996, ApJ, 462, 563 | en_US |
dc.identifier.citedreference | Navarro J. F., Frenk C. S., White S. D. M., 1997, ApJ, 490, 493 | en_US |
dc.identifier.citedreference | Navarro J. F. et al., 2010, MNRAS, 402, 21 | en_US |
dc.identifier.citedreference | Neyrinck M. C., Gnedin N. Y., Hamilton A. J. S., 2005, MNRAS, 356, 1222 | en_US |
dc.identifier.citedreference | O’Shea B. W., Bryan G., Bordner J., Norman M. L., Abel T., Harkness R., Kritsuk A., 2004, preprint (arXiv e‐prints) | en_US |
dc.identifier.citedreference | O’Shea B. W., Nagamine K., Springel V., Hernquist L., Norman M. L., 2005, ApJS, 160, 1 | en_US |
dc.identifier.citedreference | Pen U., 1995, ApJS, 100, 269 | en_US |
dc.identifier.citedreference | Pfitzner D. W., Salmon J. K., 1996, Parallel Halo Finding in N‐body Cosmology Simulations. Astron. Rechen‐Institut. Heidelberg, Germany | en_US |
dc.identifier.citedreference | Planelles S., Quilis V., 2010, A&A, 519, A94 | en_US |
dc.identifier.citedreference | Plummer H. C., 1911, MNRAS, 71, 460 | en_US |
dc.identifier.citedreference | Press W. H., Schechter P., 1974, ApJ, 187, 425 | en_US |
dc.identifier.citedreference | Quilis V., 2004, MNRAS, 352, 1426 | en_US |
dc.identifier.citedreference | Rasera Y., Alimi J., Courtin J., Roy F., Corasaniti P., Füzfa A., Boucher V., 2010, in Alimi J.‐M., Fuözfa A., eds, AIP Conf. Ser. Vol. 1241, Invisible Universe. Am. Inst. Phys., New York, p. 1134 | en_US |
dc.identifier.citedreference | Read J. I., Wilkinson M. I., Evans N. W., Gilmore G., Kleyna J. T., 2006, MNRAS, 367, 387 | en_US |
dc.identifier.citedreference | Read J. I., Lake G., Agertz O., Debattista V. P., 2008, MNRAS, 389, 1041 | en_US |
dc.identifier.citedreference | Robertson B. E., Kravtsov A. V., Tinker J., Zentner A. R., 2009, ApJ, 696, 636 | en_US |
dc.identifier.citedreference | Schaap W. E., van de Weygaert R., 2000, A&A, 363, L29 | en_US |
dc.identifier.citedreference | Sharma S., Steinmetz M., 2006, MNRAS, 373, 1293 | en_US |
dc.identifier.citedreference | Shaw L. D., Weller J., Ostriker J. P., Bode P., 2007, ApJ, 659, 1082 | en_US |
dc.identifier.citedreference | Sheth R. K., Tormen G., 1999, MNRAS, 308, 119 | en_US |
dc.identifier.citedreference | Shiloach Y., Vishkin U., 1982, J. Algorithms, 3, 57 | en_US |
dc.identifier.citedreference | Skory S., Turk M. J., Norman M. L., Coil A. L., 2010, ApJS, 191, 43 | en_US |
dc.identifier.citedreference | Springel V., 2005, MNRAS, 364, 1105 | en_US |
dc.identifier.citedreference | Springel V., 2010, MNRAS, 401, 791 | en_US |
dc.identifier.citedreference | Springel V., White S. D. M., Tormen G., Kauffmann G., 2001a, MNRAS, 328, 726 | en_US |
dc.identifier.citedreference | Springel V., Yoshida N., White S. D. M., 2001b, New Astron., 6, 79 | en_US |
dc.identifier.citedreference | Stadel J. G., 2001, PhD thesis, Univ. Washington | en_US |
dc.identifier.citedreference | Stadel J., Potter D., Moore B., Diemand J., Madau P., Zemp M., Kuhlen M., Quilis V., 2009, MNRAS, 398, L21 | en_US |
dc.identifier.citedreference | Sutter P. M., Ricker P. M., 2010, ApJ, 723, 1308 | en_US |
dc.identifier.citedreference | Tasker E. J., Brunino R., Mitchell N. L., Michielsen D., Hopton S., Pearce F. R., Bryan G. L., Theuns T., 2008, MNRAS, 390, 1267 | en_US |
dc.identifier.citedreference | Teyssier R., 2002, A&A, 385, 337 | en_US |
dc.identifier.citedreference | Tinker J., Kravtsov A. V., Klypin A., Abazajian K., Warren M., Yepes G., Gottlöber S., Holz D. E., 2008, ApJ, 688, 709 | en_US |
dc.identifier.citedreference | Tweed D., Devriendt J., Blaizot J., Colombi S., Slyz A., 2009, A&A, 506, 647 | en_US |
dc.identifier.citedreference | van Kampen E., 1995, MNRAS, 273, 295 | en_US |
dc.identifier.citedreference | Warren M. S., Abazajian K., Holz D. E., Teodoro L., 2006, ApJ, 646, 881 | en_US |
dc.identifier.citedreference | Weller J., Ostriker J. P., Bode P., Shaw L., 2005, MNRAS, 364, 823 | en_US |
dc.identifier.citedreference | White M., 2001, A&A, 367, 27 | en_US |
dc.identifier.citedreference | White M., 2002, ApJS, 143, 241 | en_US |
dc.identifier.citedreference | Zemp M., Moore B., Stadel J., Carollo C. M., Madau P., 2008, MNRAS, 386, 1543 | en_US |
dc.owningcollname | Interdisciplinary and Peer-Reviewed |
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