A Caltech Library Service

Cluster Bulleticity

Massey, Richard and Kitching, Thomas D. and Nagai, Daisuke (2011) Cluster Bulleticity. Monthly Notices of the Royal Astronomical Society, 413 (3). pp. 1709-1716. ISSN 0035-8711. doi:10.1111/j.1365-2966.2011.18246.x.

[img] PDF - Published Version
See Usage Policy.

[img] PDF - Submitted Version
See Usage Policy.


Use this Persistent URL to link to this item:


The unique properties of dark matter are revealed during collisions between clusters of galaxies, like the bullet cluster (1E 0657-56) and baby bullet (MACSJ0025-12). These systems provide evidence for an additional, invisible mass in the separation between the distribution of their total mass, measured via gravitational lensing, and their ordinary 'baryonic' matter, measured via its X-ray emission. Unfortunately, the information available from these systems is limited by their rarity. Constraints on the properties of dark matter, such as its interaction cross-section, are therefore restricted by uncertainties in the individual systems' impact velocity, impact parameter and orientation with respect to the line of sight. Here we develop a complementary, statistical measurement in which every piece of substructure falling into every massive cluster is treated as a bullet. We define 'bulleticity' as the mean separation between dark matter and ordinary matter, and we measure the signal in hydrodynamical simulations. The phase space of substructure orbits also exhibits symmetries that provide an equivalent control test. Any detection of bulleticity in real data would indicate a difference in the interaction cross-sections of baryonic and dark matter that may rule out hypotheses of non-particulate dark matter that are otherwise able to model individual systems. A subsequent measurement of bulleticity could constrain the dark matter cross-section. Even with conservative estimates, the existing HST archive should yield an independent constraint tighter than that from the bullet cluster. This technique is then trivially extendable to, and benefits enormously from larger, future surveys.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Massey, Richard0000-0002-6085-3780
Nagai, Daisuke0000-0002-6766-5942
Additional Information:© 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS. Printed 13 January 2011. The authors would like to thank Patrick Simon, Ken Rice, Phil Marshall, Cathie Clarke, Justin Read, Johan Richard and James Taylor for conversations that spurred the development of this paper. It also benefitted greatly from helpful suggestions by the anonymous referee. RM is supported by STFC Advanced Fellowship #PP/E006450/1 and ERC grant MIRG-CT-208994. TK is supported by STFC rolling grant RA0888. DN acknowledges the support of Yale University and NSF grant AST-1009811.
Group:Keck Institute for Space Studies
Funding AgencyGrant Number
Science and Technology Facilities Council (STFC)PP/E006450/1
European Research Council (ERC)MIRG-CT-208994
Science and Technology Facilities Council (STFC)RA0888
Yale UniversityUNSPECIFIED
Issue or Number:3
Record Number:CaltechAUTHORS:20160218-132149955
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:64570
Deposited By: Colette Connor
Deposited On:18 Feb 2016 22:53
Last Modified:10 Nov 2021 23:32

Repository Staff Only: item control page