ChemInform Abstract: Nucleophilic Reaction of Azulene Derivatives with Some Ketone Enolates.

Fukazawa, Yoshimasa; Usui, Shuji; Kurata, Y.; Takeda, Yasuhiro; Saito, Nozomu

doi:10.1002/chin.198946140

Cited by 14 publications

(23 citation statements)

References 1 publication

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“…Model DOF 2527DOF /1153DOF 2502DOF /1152DOF 1975DOF /1150DOF 1950DOF /1149DOF 2018DOF /1150 kT approximately constant mass-weighted temperature over the bulk of the radius in a cluster cooling flow is consistent with current constraints on the distribution of gravitating matter in the core regions of massive clusters from X-ray and gravitational lensing studies (Allen 1998) and with previous, spatially resolved spectroscopic X-ray studies of nearby clusters cooling flows with ASCA (e.g. Fukazawa et al 1994;Ohashi et al 1997;Ikebe et al 1999). The assumption of an approximately isothermal mean gas temperature in cooling flows also leads to a more plausible implied distribution of initial density inhomogeneities in the cluster gas than would be the case if the temperature profiles dropped significantly within the core regions (Thomas et al 1987).…”

Section: Parameterssupporting

confidence: 84%

“…More detailed multiphase spectral studies with ASCA have also revealed the presence of at least two gas phases in the central regions of cooling-flow clusters, with a ratio of emission measures in good agreement with the predictions from cooling-flow models (e.g. Fabian et al 1994b;Fukazawa et al 1994;Allen 2000).…”

Section: Introductionsupporting

confidence: 56%

“…For this reason the mass deposition rates measured by Fabian et al (1994b) are approximately 2 times smaller than those reported here. Fukazawa et al (1994) present an analysis of a previous, shorter ASCA observation of central regions of the Centaurus cluster (the same data as studied by Fabian et al 1994b). These authors reported the discovery of a strong metallicity gradient in the cluster, with a central metallicity and temperature in good agreement with the results presented here.…”

Section: Comparison With Previous Resultsmentioning

confidence: 97%

“…Where spectral model D provides a significantly better fit to the observations than models C and E, this need indicate only that the simple cooling-flow models over-simplify the true emission spectra from the central regions of the clusters. In particular, given that the systems studied here are the nearest, Xray-brightest cluster cooling flows, in which strong radial variations in metallicity and intrinsic absorption are known exist (Fukazawa et al 1994;Matsumoto et al 1996;Allen & Fabian 1997) and in which clear deviations from solar abundance ratios are observed (Section 5), the fact that the basic cooling-flow models over-simplify the observed situation is to be expected.…”

Section: A Note On Two-temperature Modelsmentioning

confidence: 90%

“…Further complications in the modelling of the X-ray spectra arise from abundance gradients (e.g. Fukazawa et al 1994;Matsumoto et al 1996;, the effects of intrinsic absorption (e.g. White et al 1991;Allen & Fabian 1997;Wise & Sarazin 2001), and temperature variations within the flows, which depend upon the details of the local gravitational potentials.…”

Section: Introductionmentioning

confidence: 99%

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ASCA and ROSAT observations of nearby cluster cooling flows

Allen

Fabian

Johnstone

et al. 2001

Monthly Notices of the Royal Astronomical Society

106

129

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We present a detailed analysis of the X-ray properties of the cooling flows in a sample of nearby, X-ray bright clusters of galaxies using high-quality ASCA spectra and ROSAT X-ray images. We demonstrate the need for multiphase models to consistently explain the spectral and imaging X-ray data for the clusters. The mass deposition rates of the cooling flows, independently determined from the ASCA spectra and ROSAT images, exhibit reasonable agreement. We confirm the presence of intrinsic X-ray absorption in the clusters using a variety of spectral models. We also report detections of extended $100\mu$m infrared emission, spatially coincident with the cooling flows, in several of the systems studied. The observed infrared fluxes and flux limits are in good agreement with the predicted values due to reprocessed X-ray emission from the cooling flows. We present precise measurements of the abundances of iron, magnesium, silicon and sulphur in the central regions of the Virgo and Centaurus clusters. Our results firmly favour models in which a high mass fraction (70-80 per cent) of the iron in the X-ray gas in these regions is due to Type Ia supernovae. Finally, we present a series of methods which may be used to measure the ages of cooling flows from the X-ray data. The results for the present sample of clusters indicate ages of between 2.5 and 7 Gyr. If the ages of cooling flows are primarily set by subcluster merger events, then our results suggest that in the largest clusters, mergers with subclusters with masses of approximately 30 per cent of the final cluster mass are likely to disrupt cooling flows.Comment: Final version. MNRAS, in press. 36 pages, 9 figs, 14 tables in MNRAS LaTex styl

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Section: Parameterssupporting

confidence: 84%

Section: Introductionsupporting

confidence: 56%

Section: Comparison With Previous Resultsmentioning

confidence: 97%

Section: A Note On Two-temperature Modelsmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

ASCA and ROSAT observations of nearby cluster cooling flows

Allen

Fabian

Johnstone

et al. 2001

Monthly Notices of the Royal Astronomical Society

106

129

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The missing soft X-ray luminosity in cluster cooling flows

Fabian

Allen

Crawford

et al. 2002

Monthly Notices of the Royal Astronomical Society

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The gas temperature in the cores of many clusters of galaxies drops inward by about a factor of 3 or more within the central 100‐kpc radius. The radiative cooling time drops over the same region from 5 or more Gyr down to below a few 108 yr. Although this indicates that cooling flows are taking place, XMM‐Newton spectra show no evidence for strong mass cooling rates of gas below 1–2 keV. The soft X‐ray luminosity expected from steady cooling flows is missing. Here we outline and test the energetics of a cold mixing model in which gas below 1–2 keV falls from the flow and is rapidly cooled by mixing with cold gas. The missing X‐ray luminosity can emerge in the ultraviolet, optical and infrared bands, where strong emission nebulosities are commonly seen. We explore further the requirements for any heat sources that balance the radiative cooling in cluster cores.

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A gravitational contribution to the cooling flow problem

Fabian¹

2003

Monthly Notices RAS

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X‐ray spectra of cooling flow clusters have shown that the gas temperature drops by about a factor of 3 over the central region where the radiative cooling time drops to 108 yr or less, yet does not appear to cool further. This cooling flow problem can be solved by a well‐matched, distributed energy source throughout the inner region of a cluster. Here it is proposed that the gravitational potential of the cluster (and central giant galaxy) can contribute to that source. The intracluster medium is assumed to be magnetized and so thermally unstable and, crucially, overdense blobs are assumed to slip from the flow and fall inward. The gravitational accretion energy which would be released locally in a comoving flow is instead dissipated nearer the centre, offsetting the cooling there. The energetics of the process are studied here for the case of A2199. The virial theorem leads to the thermal and gravitational energies being well‐matched in all clusters and groups. Evidence for the infall of lower metallicity gas in cluster cores may be found in the off‐centre abundance peaks of several well‐studied clusters.

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ChemInform Abstract: Nucleophilic Reaction of Azulene Derivatives with Some Ketone Enolates.

Cited by 14 publications

References 1 publication

ASCA and ROSAT observations of nearby cluster cooling flows

ASCA and ROSAT observations of nearby cluster cooling flows

The missing soft X-ray luminosity in cluster cooling flows

A gravitational contribution to the cooling flow problem

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