CLASH–VLT: CONSTRAINTS ON THE DARK MATTER EQUATION OF STATE FROM ACCURATE MEASUREMENTS OF GALAXY CLUSTER MASS PROFILES
CLASH–VLT: CONSTRAINTS ON THE DARK MATTER EQUATION OF STATE FROM ACCURATE MEASUREMENTS OF GALAXY CLUSTER MASS PROFILES
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DOI：
10.1088/2041-8205/783/1/l11
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发表时间：
2014-01
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通讯作者：
B. Sartoris;A. Biviano;P. Rosati;S. Borgani;K. Umetsu;M. Bartelmann;M. Girardi;C. Grillo;D. Lemze;A. Zitrin;I. Balestra;A. Mercurio;M. Nonino;M. Postman;N. Czakon;L. Bradley;T. Broadhurst;D. Coe;E. Medezinski;Peter Melchior;M. Meneghetti;J. Merten;M. Annunziatella;N. Benı́tez;O. Czoske;M. Donahue;S. Ettori;H. Ford;A. Fritz;D. Kelson;A. Koekemoer;U. Kuchner;M. Lombardi;C. Maier;Leonidas A. Mou;E. Munari;V. Presotto;M. Scodeggio;S. Seitz;P. Tozzi;Wei Zheng;B. Ziegler
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作者：
B. Sartoris;A. Biviano;P. Rosati;S. Borgani;K. Umetsu;M. Bartelmann;M. Girardi;C. Grillo;D. Lemze;A. Zitrin;I. Balestra;A. Mercurio;M. Nonino;M. Postman;N. Czakon;L. Bradley;T. Broadhurst;D. Coe;E. Medezinski;Peter Melchior;M. Meneghetti;J. Merten;M. Annunziatella;N. Benı́tez;O. Czoske;M. Donahue;S. Ettori;H. Ford;A. Fritz;D. Kelson;A. Koekemoer;U. Kuchner;M. Lombardi;C. Maier;Leonidas A. Mou;E. Munari;V. Presotto;M. Scodeggio;S. Seitz;P. Tozzi;Wei Zheng;B. Ziegler
暗物质（DM）流体的无压场景是一个广泛采用的假设，尽管缺乏直接的观测证据。根据广义相对论，一个系统的总质能含量很好地塑造了引力势，但是不同的测试粒子根据它们的性质以不同的方式感知这种势。星系团的速度，是π c，只取决于引力势，而光子轨迹反映的贡献，从引力势加上相对论压力项，取决于集群的质量。我们利用这种现象来约束状态方程（EoS）参数的流体，主要是DM，包含在星系团。我们使用星系团MACS 1206.2−0847在z = 0.44时的运动学和透镜质量剖面提供的补充信息，这些信息是在哈勃望远镜的星团透镜和超新星巡天中进行的广泛成像和光谱活动中获得的。前所未有的高质量的数据集和这个集群的属性非常适合于确定集群流体的EoS参数。由于重子在团簇中的贡献最多为总质量的15%，并且它们的压力可以忽略不计，因此我们得到的EoS参数描述了DM流体的行为。我们得到了迄今为止对DM EoS参数的最严格的约束，w =（pr + 2 pt）/（3 c2ρ）= 0.00 ± 0.15（stat）± 0.08（syst），在径向范围0.5 Mpc？r？r 200上取平均值，其中pr和pt是径向和切向压力，ρ是密度。我们计划通过将相同的程序应用于正在进行的哈勃甚大望远镜星团透镜和超新星巡天计划中的所有星团来进一步改进我们的约束。
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 ≪c, 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 c2ρ) = 0.00 ± 0.15 (stat) ± 0.08 (syst), averaged over the radial range 0.5 Mpc ⩽ r ⩽ r200, 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.