Dark Matter Subhalos and the X-Ray Morphology of the Coma Cluster

Andrade-Santos, Felipe; Nulsen, P. E. J.; Kraft, Ralph; Forman, W.; Jones, Christine; Churazov, E.; Vikhlinin, A.

doi:10.1088/0004-637x/766/2/107

Cited by 25 publications

(18 citation statements)

References 29 publications

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“…The center of the Coma galaxy cluster is dominated by two giant ellipticals, NGC 4874 and NGC 4889. Measurements by Okabe et al (2010, with h = 0.678 from Planck Collaboration et al 2014 and Andrade-Santos et al (2013) resulted in halo masses of 6.7 · 10 12 M and 7.6 · 10 12 M for NGC 4874, and 11.4 · 10 12 M and 9.1 · 10 12 M for NGC 4889, respectively. In comparison, Richtler et al (2008, their Table 1) estimated a halo mass of 3.5 · 10 12 M for NGC 1399 within a radius of 80 kpc.…”

Section: Formation Of Ngc 1399 and Its Gc/ucd Systemmentioning

confidence: 98%

Distribution of star formation rates during the rapid assembly of NGC 1399 as deduced from its globular cluster system

Schulz¹,

Hilker²,

Kroupa³

et al. 2016

A&A

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Ultra-compact dwarf galaxies (UCDs) share many properties with globular clusters (GCs) and are found in similar environments. Here, a large sample of UCDs and GCs around NGC 1399, the central giant elliptical of the Fornax galaxy cluster, is used to infer their formation history and also to shed light on the formation of NGC 1399 itself. We assumed that all GCs and UCDs in our sample are the result of star cluster (SC) formation processes and used them as tracers of past star formation activities. After correcting our GC/UCD sample for mass loss, we interpreted their overall mass function to be a superposition of SC populations that formed coevally during different formation epochs. The SC masses of each population were distributed according to the embedded cluster mass function (ECMF), a pure power law with the slope −β. Each ECMF was characterized by a stellar upper mass limit, M max , which depended on the star formation rate (SFR). We decomposed the observed GC/UCD mass function into individual SC populations and converted M max of each SC population to an SFR. The overall distribution of SFRs reveals under which conditions the GC/UCD sample around NGC 1399 formed. Considering the constraints set by the age of the GCs/UCDs and the present stellar mass of NGC 1399, we found that the formation of the GCs/UCDs can be well explained within our framework with values for β below 2.3. This finding agrees very well with the observation in young SCs where β ≈ 2.0 is usually found. Even though we took into account that some of the most massive objects might not be genuine SCs and applied different corrections for the mass loss, we found that these considerations do not influence much the outcome. We derived the peak SFRs to be between approximately 300 and 3000 M yr −1 , which matches the SFRs observed in massive high-redshift sub-millimeter galaxies and an SFR estimate inferred from NGC 1399 based on the so-called downsizing picture, meaning that more massive galaxies must have formed over shorter periods of time. Our findings give rise to the interpretation that NGC 1399 and its GC/UCD system formed in a relatively short, intense starburst early on.

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Section: Formation Of Ngc 1399 and Its Gc/ucd Systemmentioning

confidence: 98%

Distribution of star formation rates during the rapid assembly of NGC 1399 as deduced from its globular cluster system

Schulz¹,

Hilker²,

Kroupa³

et al. 2016

A&A

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“…Three dimensional ellipticity as well as substructures of the Coma cluster have been studied in Ref. [71]. They have reported an ellipticity of the electron density in the Coma cluster of ǫ = √ 1 − e 2 = 0.84 with eccentricity e such that we can ignore the effect in our analysis.…”

Section: Non-spherical Symmetrymentioning

confidence: 98%

Testing chameleon gravity with the Coma cluster

Terukina

Lombriser

Yamamoto

et al. 2014

J. Cosmol. Astropart. Phys.

129

187

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Abstract. We propose a novel method to test the gravitational interactions in the outskirts of galaxy clusters. When gravity is modified, this is typically accompanied by the introduction of an additional scalar degree of freedom, which mediates an attractive fifth force. The presence of an extra gravitational coupling, however, is tightly constrained by local measurements. In chameleon modifications of gravity, local tests can be evaded by employing a screening mechanism that suppresses the fifth force in dense environments. While the chameleon field may be screened in the interior of the cluster, its outer region can still be affected by the extra force, introducing a deviation between the hydrostatic and lensing mass of the cluster. Thus, the chameleon modification can be tested by combining the gas and lensing measurements of the cluster. We demonstrate the operability of our method with the Coma cluster, for which both a lensing measurement and gas observations from the X-ray surface brightness, the X-ray temperature, and the Sunyaev-Zel'dovich effect are available. Using the joint observational data set, we perform a Markov chain Monte Carlo analysis of the parameter space describing the different profiles in both the Newtonian and chameleon scenarios. We report competitive constraints on the chameleon field amplitude and its coupling strength to matter. In the case of f (R) gravity, corresponding to a specific choice of the coupling, we find an upper bound on the background field amplitude of |f R0 | < 6 × 10 −5 , which is currently the tightest constraint on cosmological scales.

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“…The heliocentric radial velocity of NGC 4921, 5482 km s −1 , is somewhat smaller than that of the Coma cluster, 6925 km s −1 (Struble & Rood 1999). Thus it has been considered that NGC 4921 is infalling to the Coma cluster (Vikhlinin et al 1997;Brown & Rudnick 2011;Andrade-Santos et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Globular Clusters and Spur Clusters in NGC 4921, the Brightest Spiral Galaxy in the Coma Cluster

Lee

Jang

2016

ApJ

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We resolve a significant fraction of globular clusters (GCs) in NGC 4921, the brightest spiral galaxy in the Coma cluster. We also find a number of extended bright star clusters (star complexes) in the spur region of the arms. The latter are much brighter and bluer than those in the normal star-forming region, being as massive as 3×105 M e . The color distribution of the GCs in this galaxy is found to be bimodal. The turnover magnitudes of the luminosity functions of the blue (metal-poor) GCs (0.70<(V − I)1.05) in the halo are estimated V (max)=27.11±0.09 mag and I(max)=26.21±0.11 mag. We obtain similar values for NGC 4923, a companion S0 galaxy, and two Coma cD galaxies (NGC 4874 and NGC 4889). The mean value for the turnover magnitudes of these four galaxies is I(max)=26.25±0.03 mag. Adopting M I (max)=−8.56±0.09 mag for the metal-poor GCs, we determine the mean distance to the four Coma galaxies to be 91±4 Mpc. Combining this with the Coma radial velocity, we derive a value of the Hubble constant, H 0 =77.9±3.6 km s −1 Mpc −1 . We estimate the GC specific frequency of NGC 4921 to be S N =1.29±0.25, close to the values for early-type galaxies. This indicates that NGC 4921 is in the transition phase to S0s.

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Dark Matter Subhalos and the X-Ray Morphology of the Coma Cluster

Cited by 25 publications

References 29 publications

Distribution of star formation rates during the rapid assembly of NGC 1399 as deduced from its globular cluster system

Distribution of star formation rates during the rapid assembly of NGC 1399 as deduced from its globular cluster system

Testing chameleon gravity with the Coma cluster

Globular Clusters and Spur Clusters in NGC 4921, the Brightest Spiral Galaxy in the Coma Cluster

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