Detection of a Temperature Structure in the Coma Cluster of Galaxies with [ITAL]ASCA[/ITAL]

Honda, Hiroaki; Hirayama, M.; Watanabe, Manabu; Kunieda, H.; Tawara, Yuzuru; Yamashita, Koujun; Ohashi, T.; Hughes, John P.; Henry, J. P.

doi:10.1086/310400

Cited by 67 publications

(71 citation statements)

References 21 publications

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“…Radio (Thierbach et al 2003, and references therein) and X-ray measurements of ROSAT, ASCA and XMM-Newton (Briel et al 1992;Honda et al 1996;Briel et al 2001;Neumann et al 2003) confirmed this suspicion. The X-ray structure of the cluster detected by ROSAT and ASCA extends ∼1…”

Section: Excessmentioning

confidence: 91%

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Gamma-ray line emission from galaxy clusters

Iyudin

Böhringer

Dogiel

et al. 2004

A&A

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Abstract. We report first results of a study dedicated to a search for γ-ray line emission from rich galaxy clusters, finding traces of emission from the region of Virgo and Coma near the Northern Galactic Pole (NGP). The study is based on the 6 years of COMPTEL data collected during the extended observational programme of the Compton Gamma Ray Observatory (CGRO) monitoring of the Virgo and 3C273 region. We point out the advantages of performing this study using an energy range that contains the strongest excitation γ-ray lines of 16 O at 6.13, 6.9 and 7.1 MeV, as well as lines at 6.175 MeV ( 15 O * ) and 6.322 MeV ( 15 N * ) of the spallation products of the cosmic ray interactions with 16 O. We discuss a generation mechanism for γ-ray line emission in merging clusters via excitation of the abundant element(s) of the intracluster matter at the merger shock by the subrelativistic protons accelerated to energies of ∼10 MeV to ∼100 MeV/n in the merger process.

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Section: Excessmentioning

confidence: 91%

“…• off the cluster core to the south-west direction (Briel et al 1992;Honda et al 1996). This structure, seen in the X-ray brightness and temperature distributions, is explained by the merging process of NGC 4839 with the Coma cluster.…”

Section: Excessmentioning

confidence: 97%

Gamma-ray line emission from galaxy clusters

Iyudin

Böhringer

Dogiel

et al. 2004

A&A

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“…10a, 11a, and 12). However, it is smaller than the model for a major merger (D1044 ergs s~1), although the Coma Cluster is known as a merging cluster (see, e.g., Briel, Henry, & 1992 ;Bo hringer Vikhlinin, Forman, & Jones 1997 ;Honda et al 1996 ;Watanabe et al 1999). The low luminosity suggests that the ratio of mass between the main cluster and the merger subcluster or subclusters is fairly high.…”

Section: Hard X-ray Emissionmentioning

confidence: 94%

Nonthermal Emission from Accreting and Merging Clusters of Galaxies

Fujita

Sarazin

2001

ApJ

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We compare the nonthermal emission from clusters of galaxies undergoing minor mergers ("" accreting ÏÏ clusters) and major mergers ("" merging ÏÏ clusters). We deÐne major mergers as mergers that change the inner dark matter structure of clusters ; minor mergers are all others. For accreting clusters, the radial distribution of the nonthermal emission in the clusters is also calculated. The relativistic electrons, which are the origin of the nonthermal radiation through inverse Compton (IC) and synchrotron emission, are assumed to be accelerated at shocks produced by accretion or mergers. We estimate the typical accretion rate and merger probability according to a hierarchical clustering model. We predict that in the inner region of accreting clusters the nonthermal emission has a Ñat spatial distribution at all frequencies. For synchrotron and hard X-ray emissions, we predict an increase in the emissions at the cluster edge due to accretion. We show that the total luminosities of IC emission from accreting and merging clusters are similar. On the other hand, the luminosity of synchrotron radio emission of the former is much smaller than that of the latter. We show that about 10% of clusters at z D 0 should have hard X-ray and radio nonthermal emissions due to their last major merger that are comparable to or dominate those due to ongoing accretion. Moreover, 20%È40% of clusters should have signiÐcant EUV emission due to their last merger. We also investigate the case where the criterion of mergers is relaxed. If we extend the deÐnition of a merger to an increase in the mass of the larger subcluster by at least 10% of its initial mass, about 20%È30% of clusters at z D 0 should have hard X-ray and radio nonthermal emissions due to the merger, even in a low-density universe. We compare the results with observations. We Ðnd that the observed EUV emission from clusters is not attributed to accretion. If the di †use radio emission observed in clusters is synchrotron emission from electrons accelerated via accretion or merging, the magnetic Ðelds of clusters are generally as small as D0.1 kG. One concern is that this is a signiÐcantly weaker Ðeld than that implied by Faraday rotation measurements.

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“…Subsequent pointed observations with Rosat showed that Coma has irregular structure on different scales and was most probably formed by hierarchical clustering of several subunits, which are still visible in their X-ray emission (White et al 1993). Observations with ASCA, and also the pointed Rosat observation, showed evidence of temperature structure in Coma (Honda et al 1996;Briel & Henry 1998;Donnelly et al 1999;Watanabe et al 1999). The interpretation of the temperature structure favors the ongoing merging of the subgroup around NGC 4839 with the main cluster, a scenario which is still debated.…”

Section: Introductionmentioning

confidence: 92%

A mosaic of the Coma cluster of galaxies with XMM-Newton

Briel

Henry²,

Lumb³

et al. 2001

A&A

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Abstract. The Coma cluster of galaxies was observed with XMM-Newton in 12 partially overlapping pointings. We present here the resulting X-ray map in different energy bands and discuss the large scale structure of this cluster. Many point sources were found throughout the observed area, at least 11 of them are coincident with bright galaxies. We also give a hardness ratio map at the so far highest angular resolution obtained for a cluster of galaxies. In this map we found soft regions at the position of bright galaxies, little variation in the central 15 arcmin, but some harder regions north of the line NGC 4874 -NGC 4889.

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Detection of a Temperature Structure in the Coma Cluster of Galaxies with [ITAL]ASCA[/ITAL]

Cited by 67 publications

References 21 publications

Gamma-ray line emission from galaxy clusters

Gamma-ray line emission from galaxy clusters

Nonthermal Emission from Accreting and Merging Clusters of Galaxies

A mosaic of the Coma cluster of galaxies with XMM-Newton

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