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  • 1
    Publication Date: 2004-12-03
    Description: The results of spectral and spatial analysis of overlapping Rosat position sensitive proportional counter (PSPC) and Advanced Satellite for Cosmology and Astrophysics (ASCA) scanning imaging spectroradiometer (SIS) observations of the NGC 2300 group are presented. The spatial analysis of the co-added fields reveals that the diffuse X-ray gas can be traced to at least 25 arcmin. The temperature of the gas was found to be approximately 0.88 keV. The mass of gas within 0.33 Mpc is equal to 1.39 x 10(exp 12) solar mass. Comparing the mass of the galaxies plus the mass of hot gas the total mass of the system yields an observed baryonic fraction of 12 percent to 18 percent.
    Keywords: Astronomy
    Type: ; 575-576
    Format: text
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  • 2
    Publication Date: 2018-06-06
    Description: Images and the radial profiles of the temperature, abundance, and brightness for 70 clusters of galaxies observed by XMM-Newton are presented along with a detailed discussion of the data reduction and analysis methods, including background modeling, which were used in the processing. Proper consideration of the various background components is vital to extend the reliable determination of cluster parameters to the largest possible cluster radii. The various components of the background including the quiescent particle background, cosmic diffuse emission, soft proton contamination, and solar wind charge exchange emission are discussed along with suggested means of their identification, filtering, and/or their modeling and subtraction. Every component is spectrally variable, sometimes significantly so, and all components except the cosmic background are temporally variable as well. The distributions of the events over the FOV vary between the components, and some distributions vary with energy. The scientific results from observations of low surface brightness objects and the diffuse background itself can be strongly affected by these background components and therefore great care should be taken in their consideration.
    Keywords: Astronomy
    Format: application/pdf
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  • 3
    Publication Date: 2019-07-12
    Description: We present our X-ray imaging spectroscopic analysis of data from deep Suzuku and XMM-Newton Observatory exposures of the Virgo Cluster elliptical galaxy NGC 4649 (M60), focusing on the abundance pattern in the hot interstellar medium (ISM). All measured elements show a radial decline in abundance, with the possible exception of O. We construct steady state solutions to the chemical evolution equations that include infall in addition to stellar mass return and SNIa enrichment, and consider recently published SNIa yields. By adjusting a single model parameter to obtain a match to the global abundance pattern in NGC 4649 we infer that accretion of subsolar metallicity external gas has reduced the overall ISM metallicity and diluted the effectiveness of SNIa to skew the pattern towards low alpha/Fe ratios, and estimate the combination of SNIa rate and level of dilution. Evidently, newly-introduced gas is heated as it is integrated into. and interacts with, the hot gas that is already present. These results indicate a complex flow and enrichment history for NGC 4649, reflecting the continual evolution of elliptical galaxies beyond the formation epoch. The heating and circulation of accreted gas may help reconcile this dynamic history with the mostly passive evolution of elliptical stellar populations. In an appendix we examine the effects of the recent updated atomic database AtomDB in spectral fitting of thermal plasmas with hot ISM temperatures in the elliptical galaxy range.
    Keywords: Astronomy
    Type: GSFC.JA.6268.2012
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  • 4
    Publication Date: 2019-07-13
    Description: A search was conducted for a hot intragroup medium in 10(exp 9) low-redshift galaxy groups observed with the ROSAT PSPC. Evidence for diffuse, extended X-ray emission is found in at least 61 groups. Approximately one-third of these detections have not been previously reported in the literature. Most of the groups are detected out to less than half of the virial radius with ROSAT. Although some spiral-rich groups do contain an intragroup medium, diffuse emission is restricted to groups that contain at least one early-type galaxy.
    Keywords: Astronomy
    Type: Astrophysical Journal Supplement Series; 145; 39-64
    Format: text
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