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CLASH-VLT: Constraints on the Dark Matter Equation of State from Accurate Measurements of Galaxy Cluster Mass Profiles

Sartoris, Barbara and Zitrin, Adi (2014) CLASH-VLT: Constraints on the Dark Matter Equation of State from Accurate Measurements of Galaxy Cluster Mass Profiles. Astrophysical Journal Letters, 783 (1). Art. No. L11. ISSN 2041-8205. doi:10.1088/2041-8205/783/1/L11.

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A pressureless scenario for the dark matter (DM) fluid is a widely adopted hypothesis, despite the absence of direct observational evidence. According to general relativity, the total mass–energy content of a system shapes the gravitational potential well, but different test particles perceive this potential in different ways depending on their properties. Cluster galaxy velocities, being Ltc, depend solely on the gravitational potential, whereas photon trajectories reflect the contributions from the gravitational potential plus a relativistic-pressure term that depends on the cluster mass. We exploit this phenomenon to constrain the equation of state (EoS) parameter of the fluid, primarily DM, contained in galaxy clusters. We use complementary information provided by the kinematic and lensing mass profiles of the galaxy cluster MACS 1206.2−0847 at z = 0.44, as obtained in an extensive imaging and spectroscopic campaign within the Cluster Lensing And Supernova survey with Hubble. The unprecedented high quality of our data set and the properties of this cluster are well suited to determine the EoS parameter of the cluster fluid. Since baryons contribute at most 15% to the total mass in clusters and their pressure is negligible, the EoS parameter we derive describes the behavior of the DM fluid. We obtain the most stringent constraint on the DM EoS parameter to date, w = (pr + 2 pt)/(3 c^(2)ρ) = 0.00 ± 0.15 (stat) ± 0.08 (syst), averaged over the radial range 0.5 Mpc ≤ r ≤ r_200, where pr and pt are the radial and tangential pressure, and ρ is the density. We plan to further improve our constraint by applying the same procedure to all clusters from the ongoing Cluster Lensing And Supernova Survey with Hubble–Very Large Telescope program.

Item Type:Article
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URLURL TypeDescription Paper
Zitrin, Adi0000-0002-0350-4488
Additional Information:© 2014 American Astronomical Society. Received 2013 November 18; accepted 2014 January 21; published 2014 February 14. We thank the referee, Michael Strauss, for his constructive and thoughtful comments. B.S. thanks Marino Mezzetti and Pierluigi Monaco for useful discussions. This work has been partially supported by the PRIN-MIUR09 “Tracing the Growth of Structures in the Universe,” by the PD51 INFN grant and by the PRIN INAF 2010 “Architecture and Tomography of Galaxy Clusters.” P.R. acknowledges partial support by the DFG Cluster of Excellence Origin and Structure of the Universe ( Support for A.Z. was provided by NASA through Hubble Fellowship grant HST-HF-51334.01-A awarded by STScI.A.F. acknowledges the support by INAF through PRIN 2008 (VIPERS) and PRIN 2010 (VIPERS) grants. This research was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA.
Funding AgencyGrant Number
Ministero dell'Istruzione, dell'Università e della Ricerca (MIUR)UNSPECIFIED
Istituto Nazionale di Astrofisica (INAF)PRIN 2008 (VIPERS)
Istituto Nazionale di Astrofisica (INAF)PRIN 2010 (VIPERS)
Deutsche Forschungsgemeinschaft (DFG)UNSPECIFIED
NASA Hubble FellowshipHST-HF-51334.01-A
Subject Keywords:cosmology: theory; dark matter; equation of state; galaxies: clusters: general; galaxies: clusters: individual (1206.2–0847)
Issue or Number:1
Record Number:CaltechAUTHORS:20140428-102457504
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Official Citation:CLASH-VLT: Constraints on the Dark Matter Equation of State from Accurate Measurements of Galaxy Cluster Mass Profiles Barbara Sartoris et al. 2014 ApJ 783 L11
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:45242
Deposited By: Jason Perez
Deposited On:29 Apr 2014 18:07
Last Modified:10 Nov 2021 17:01

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