The Effect of Gas Cooling on the Shapes of Dark Matter Halos

Kazantzidis, Stelios; Kravtsov, Andrey V.; Zentner, Andrew R.; Allgood, Brandon; Nagai, Daisuke; Moore, Ben

doi:10.1086/423992

Cited by 333 publications

(433 citation statements)

References 43 publications

Supporting

Mentioning

400

Contrasting

Order By: Relevance

“…In clusters, the dominant form of atomic matter is not stars, but hot gas. Gas cooling does not have a major effect on the profiles except close to the inner regions of the cluster, roughly r < 0.1R vir (Kazantzidis et al 2004;Duffy et al 2010;Cui et al 2011). Beyond this radius the gas distribution is determined by the self-consistent gravitational potential.…”

Section: Halos and Concentrationsmentioning

confidence: 93%

Dark Matter Halo Profiles of Massive Clusters: Theory Versus Observations

Bhattacharya

Habib

Heitmann

et al. 2013

ApJ

240

332

View full text Add to dashboard Cite

Dark matter-dominated cluster-scale halos act as an important cosmological probe and provide a key testing ground for structure formation theory. Focusing on their mass profiles, we have carried out (gravity-only) simulations of the concordance ΛCDM cosmology, covering a mass range of 2 × 10 12 − 2 × 10 15 h −1 M ⊙ and a redshift range of z = 0 − 2, while satisfying the associated requirements of resolution and statistical control. When fitting to the Navarro-Frenk-White profile, our concentration-mass (c − M) relation differs in normalization and shape in comparison to previous studies that have limited statistics in the upper end of the mass range. We show that the flattening of the c − M relation with redshift is naturally expressed if c is viewed as a function of the peak height parameter, ν. Unlike the c − M relation, the slope of the c − ν relation is effectively constant over the redshift range z = 0 − 2, while the amplitude varies by ∼ 30% for massive clusters. This relation is, however, not universal: Using a simulation suite covering the allowed wCDM parameter space, we show that the c − ν relation varies by about ± 20% as cosmological parameters are varied. At fixed mass, the c(M) distribution is well-fit by a Gaussian with σ c / c ≃ 0.33, independent of the radius at which the concentration is defined, the halo dynamical state, and the underlying cosmology. We compare the ΛCDM predictions with observations of halo concentrations from strong lensing, weak lensing, galaxy kinematics, and X-ray data, finding good agreement for massive clusters (M vir > 4 × 10 14 h −1 M ⊙ ), but with some disagreements at lower masses. Because of uncertainty in observational systematics and modeling of baryonic physics, the significance of these discrepancies remains unclear.

show abstract

Section: Halos and Concentrationsmentioning

confidence: 93%

Dark Matter Halo Profiles of Massive Clusters: Theory Versus Observations

Bhattacharya

Habib

Heitmann

et al. 2013

ApJ

240

332

View full text Add to dashboard Cite

show abstract

“…Previous hydrodynamical numerical studies of galaxy formation have found that the cooling of baryons leads to significantly rounder halos (Dubinski 1994;Kazantzidis et al 2004;Springel et al 2004;, especially in the central regions where s can increase by as much as 0.2-0.3. At the moment it is unclear how much of this effect is due to a potential overcooling problem in these simulations.…”

Section: Host Halo Shapementioning

confidence: 96%

The Shapes, Orientation, and Alignment of Galactic Dark Matter Subhalos

Kuhlen

Diemand

Madau

2007

ApJ

145

210

View full text Add to dashboard Cite

We present a study of the shapes, orientations, and alignments of Galactic dark matter subhalos in the Via Lactea simulation of a Milky Way-size ÃCDM host halo. Whereas isolated dark matter halos tend to be prolate, subhalos are predominantly triaxial. Overall subhalos are more spherical than the host halo, with minor-to-major and intermediateto-major axis ratios of 0.68 and 0.83, respectively. Like isolated halos, subhalos tend to be less spherical in their central regions. The principal axis ratios are independent of subhalo mass when the shapes are measured within a physical scale such as r V max , the radius of the peak of the circular velocity curve. Subhalos tend to be slightly more spherical closer to the host halo center. The spatial distribution of the subhalos traces the prolate shape of the host halo when they are selected by the largest V max they ever had, i.e., before they experienced strong tidal mass loss. The subhalos' orientation is not random: the major axis tends to align with the direction toward the host halo center. This alignment disappears for halos beyond 3r 200 and is more pronounced when the shapes are measured in the outer regions of the subhalos. The radial alignment is preserved during a subhalo's orbit and they become elongated during pericenter passage, indicating that the alignment is likely caused by the host halo's tidal forces. These tidal interactions with the host halo act to make subhalos rounder over time.

show abstract

“…We have relied heavily on the hypothesis that the BCG is somewhat aligned with the dark matter in the galaxy cluster. Finally, we have drawn some loose conclusions about the efficacy of this approach in differentiating the predictions of CDM and the hydrodynamic simulations of [3], but we note that these are likely to be altered by the influence of baryons on substructure. We hope that future work will address these issues.…”

Section: Discussionmentioning

confidence: 93%

“…The conventional belief is that since the baryons are a small fraction of the total cluster mass, baryonic physics has a negligible effect on the halo shape out near the virial radius. However one group [3] has presented evidence to the contrary from numerical simulations of cluster formation which include gas cooling and feedback processes. They suggest that particle orbits are circularized by gravitational interaction with the deeper potential wells from baryonic cooling in the cluster's core, leading to an observable change in halo shape even at large radius.…”

Section: Introductionmentioning

confidence: 99%