Direct Constraints on the Dark Matter Self‐Interaction Cross Section from the Merging Galaxy Cluster 1E 0657−56

Markevitch, M.; Gonzalez, Anthony H.; Clowe, Douglas; Vikhlinin, A.; Forman, W.; Jones, C.; Murray, Stephen S.; Tucker, W.

doi:10.1086/383178

Cited by 836 publications

(970 citation statements)

References 32 publications

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“…Other insights into A1240 might be recovered by a clearer knowledge of galaxy properties, e.g., spectral signatures of past activity, which could be useful in determining the relevant timescales (see e.g., Ferrari et al 2003;Boschin et al 2004) and from deeper X-ray observations (see, e.g Vikhlinin et al 2001, for the discovery of a "cold front" in Abell 3667). Finally, we point out that A1240, with its displacement between collisional (gas) and collisionless components (galaxies), is an excellent candidate for studying the properties of dark matter, in particular its collisional cross-section, as already performed for other merging clusters (Markevitch et al 2004;Bradǎc et al 2008).…”

Section: Discussionmentioning

confidence: 57%

Internal dynamics of Abell 1240: a galaxy cluster with symmetric double radio relics

Barrena¹,

Girardi

Boschin

et al. 2009

A&A

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Context. The mechanisms giving rise to diffuse radio emission in galaxy clusters, and in particular their connection with cluster mergers, are still debated. Aims. We aim to obtain new insights into the internal dynamics of the cluster Abell 1240, which appears to contain two roughly symmetric radio relics, separated by ∼2 h −1 70 Mpc. Methods. Our analysis is based mainly on redshift data for 145 galaxies mostly acquired at the Telescopio Nazionale Galileo and on new photometric data acquired at the Isaac Newton Telescope. We also use X-ray data from the Chandra archive and photometric data from the Sloan Digital Sky Survey (Data Release 7). We combine galaxy velocities and positions to select 89 cluster galaxies and analyze the internal dynamics of the Abell 1237 + Abell 1240 cluster complex, Abell 1237 being a close companion of Abell 1240 in its southern direction. Results. We estimate similar redshifts for Abell 1237 and Abell 1240, z = 0.1935 and z = 0.1948, respectively. For Abell 1237, we estimate a line-of-sight (LOS) velocity dispersion of σ V ∼ 740 km s −1 and a mass of M ∼ 6 × 10 14 h −1 70 M . For Abell 1240, we estimate a LOS σ V ∼ 870 km s −1 and a mass in the range M ∼ 0.9−1.9 × 10 15 h −1 70 M , which takes account of its complex dynamics. Abell 1240 is shown to have a bimodal structure with two galaxy clumps roughly aligned along its N-S direction, the same as defined by the elongation of its X-ray surface brightness and the axis of symmetry of the relics. The two brightest galaxies of Abell 1240, associated with the northern and southern clumps, are separated by a LOS rest-frame velocity difference V rf ∼ 400 km s −1 and a projected distance D ∼ 1.2 h −1 70 Mpc. The two-body model agrees with the hypothesis that we are looking at a cluster merger that occurred largely in the plane of the sky, the two galaxy clumps being separated by a rest-frame velocity difference V rf ∼ 2000 km s −1 at a time of 0.3 Gyr after the crossing core, while Abell 1237 is still infalling onto Abell 1240. Chandra archive data confirm the complex structure of Abell 1240 and allow us to estimate a global X-ray temperature of T X = 6.0 ± 0.5 keV. Conclusions. In agreement with the findings from radio data, our results for Abell 1240 strongly support the "outgoing merger shocks" model to explain the presence of the relics.

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Section: Discussionmentioning

confidence: 57%

Internal dynamics of Abell 1240: a galaxy cluster with symmetric double radio relics

Barrena¹,

Girardi

Boschin

et al. 2009

A&A

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“…Dark matter is now an observational fact. We see the effects of dark matter from rotation curves [356], gravitational lensing [357], the Bullet cluster [358,359], and even in the cosmic microwave background [10]. In fact, the CMB shows that nearly 85% of the matter in the Universe is dark matter [10].…”

Section: New Particles and Structure Formationmentioning

confidence: 99%

BeyondΛCDM: Problems, solutions, and the road ahead

Bull

Akrami

Adamek

et al. 2016

Physics of the Dark Universe

420

210

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Despite its continued observational successes, there is a persistent (and growing) interest in extending cosmology beyond the standard model, ΛCDM. This is motivated by a range of apparently serious theoretical issues, involving such questions as the cosmological constant problem, the particle nature of dark matter, the validity of general relativity on large scales, the existence of anomalies in the CMB and on small scales, and the predictivity and testability of the inflationary paradigm. In this paper, we summarize the current status of ΛCDM as a physical theory, and review investigations into possible alternatives along a number of different lines, with a particular focus on highlighting the most promising directions. While the fundamental problems are proving reluctant to yield, the study of alternative cosmologies has led to considerable progress, with much more to come if hopes about forthcoming high-precision observations and new theoretical ideas are fulfilled.Keywords: cosmology -dark energy -cosmological constant problem -modified gravitydark matter -early universe Cosmology has been both blessed and cursed by the establishment of a standard model: ΛCDM. On the one hand, the model has turned out to be extremely predictive, explanatory, and observationally robust, providing us with a substantial understanding of the formation of large-scale structure, the state of the early Universe, and the cosmic abundance of different types of matter and energy. It has also survived an impressive battery of precision observational tests -anomalies are few and far between, and their significance is contentious where they do arise -and its predictions are continually being vindicated through the discovery of new effects (B-mode polarization [1] and lensing [2,3] of the cosmic microwave background (CMB), and the kinetic Sunyaev-Zel'dovich effect [4] being some recent examples). These are the hallmarks of a good and valuable physical theory.On the other hand, the model suffers from profound theoretical difficulties. The two largest contributions to the energy content at late times -cold dark matter (CDM) and the cosmological constant (Λ) -have entirely mysterious physical origins. CDM has so far evaded direct detection by laboratory experiments, and so the particle field responsible for it -presumably a manifestation of "beyond the standard model" particle physics -is unknown. Curious discrepancies also appear to exist between the predicted clustering properties of CDM on small scales and observations. The cosmological constant is even more puzzling, giving rise to quite simply the biggest problem in all of fundamental physics: the question of why Λ appears to take such an unnatural value [5,6,7]. Inflation, the theory of the very early Universe, has also been criticized for being fine-tuned and under-predictive [8], and appears to leave many problems either unsolved or fundamentally unresolvable. These problems are indicative of a crisis.From January 14th-17th 2015, we held a conference in Oslo, Norway to surve...

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“…Because they are relatively young structures, the interaction between the baryons and the dark matter is weaker than in older systems like galaxies. For this reason, clusters are important laboratories for studying the properties of the dark matter (Markevitch et al 2004). However, there are several issues that we need to consider when studying these systems.…”

Section: Introductionmentioning

confidence: 99%

Strong lensing in the MARENOSTRUM UNIVERSE

Meneghetti

Fedeli

Pace

et al. 2010

A&A

152

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Context. Strong lensing is one of the most direct probes of mass distribution in the inner regions of galaxy clusters. It can be used to constrain the density profiles and to measure the mass of the lenses. Moreover, the abundance of strong lensing events can be used to constrain structure formation and cosmological parameters through the so-called "arc-statistics" approach. However, several issues related to the use of strong lensing clusters in cosmological applications are still controversial, leading to the suspicion that several biases may affect this very peculiar class of objects. Aims. With this study we aim a better understanding of the properties of galaxy clusters that can potentially act as strong lenses. Methods. We do so by investigating the properties of a large sample of galaxy clusters extracted from the N-body/hydrodynamical simulation MareNostrum Universe. We perform ray-tracing simulations with each of them and identify those objects capable of producing strong lensing effects. We explore the correlation between the cross section for lensing and many properties of clusters, such as mass, three-dimensional and projected shapes, their concentrations, the X-ray luminosity, and the dynamical activity. Results. We quantify the minimal cluster mass required for producing both multiple images and large distortions. While we do not measure a significant excess of triaxiality in strong lensing clusters, we find that the probability of strong alignments between the major axes of the lenses and the line of sight is a growing function of the lensing cross section. In projection, the strong lenses appear rounder within R 200 , but we find that their cores tend to be more elliptical as the lensing cross section increases. As a result of the orientation bias, we also find that the cluster concentrations estimated from the projected density profiles tend to be biased high. The X-ray luminosity of strong lensing clusters tend to be higher than for normal lenses of similar mass and redshift. This is particularly significant for the least massive lenses. Finally, we find that the strongest lenses generally exhibit an excess of kinetic energy within the virial radius, thus indicating that they are more dynamically active than the usual clusters. Conclusions. We conclude that strong lensing clusters are a very peculiar class of objects, affected by many selection biases that need to be properly modeled when using them to study the inner structure of galaxy clusters or to constrain the cosmological parameters.

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Direct Constraints on the Dark Matter Self‐Interaction Cross Section from the Merging Galaxy Cluster 1E 0657−56

Cited by 836 publications

References 32 publications

Internal dynamics of Abell 1240: a galaxy cluster with symmetric double radio relics

Internal dynamics of Abell 1240: a galaxy cluster with symmetric double radio relics

BeyondΛCDM: Problems, solutions, and the road ahead

Strong lensing in the MARENOSTRUM UNIVERSE

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