Nonisothermality of the hottest cluster abell 2163

Maxim Markevitch, Koujun Yamashita, Akihiro Furuzawa, Yuzuru Tawara

Research output: Contribution to journalArticle

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Abstract

Preliminary results of the ASCA observation of A2163 are presented. Kα lines of He-like and H-like iron have been observed in the SIS spectrum at a redshift of 0.200 (0.190-0.206; hereafter the quoted errors are 90%). The flux ratio in these lines corresponds to T e = 16 keV or a 90% lower limit of 12 keV, unambiguously confirming the presence of very hot gas in this cluster. The GIS spectrum in the 2.5-12 keV band shows a temperature of T e = 12.7 ± 2.0 keV, and an iron abundance of 0.38 ± 0.13, assuming isothermality. Comparison of the deconvolved GIS cluster images in the energy bands 2.5-7 keV and 7-12 keV (rest frame) shows considerable gas temperature variations in the central 3-4 core radii region. A similar kind of nonisothermality is independently indicated, although marginally, by SIS images in the narrow energy intervals which include the 6.67 keV and 6.97 keV iron line blends. The overall picture suggests that neither the galaxies (Soucail et al. 1994) nor even the gas in A2163 are in equilibrium, and we may be currently observing a merger. If the cluster gas is not isothermal, the somewhat too high temperature derived from the iron line ratio may require a higher iron abundance in the hotter regions of the gas.

Original languageEnglish
JournalAstrophysical Journal
Volume436
Issue number1 PART 2
Publication statusPublished - 20-11-1994
Externally publishedYes

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iron
gas
GIS
gases
K lines
high temperature gases
gas temperature
merger
energy bands
energy
temperature
galaxies
intervals
radii

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Markevitch, M., Yamashita, K., Furuzawa, A., & Tawara, Y. (1994). Nonisothermality of the hottest cluster abell 2163. Astrophysical Journal, 436(1 PART 2).
Markevitch, Maxim ; Yamashita, Koujun ; Furuzawa, Akihiro ; Tawara, Yuzuru. / Nonisothermality of the hottest cluster abell 2163. In: Astrophysical Journal. 1994 ; Vol. 436, No. 1 PART 2.
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Markevitch, M, Yamashita, K, Furuzawa, A & Tawara, Y 1994, 'Nonisothermality of the hottest cluster abell 2163', Astrophysical Journal, vol. 436, no. 1 PART 2.

Nonisothermality of the hottest cluster abell 2163. / Markevitch, Maxim; Yamashita, Koujun; Furuzawa, Akihiro; Tawara, Yuzuru.

In: Astrophysical Journal, Vol. 436, No. 1 PART 2, 20.11.1994.

Research output: Contribution to journalArticle

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N2 - Preliminary results of the ASCA observation of A2163 are presented. Kα lines of He-like and H-like iron have been observed in the SIS spectrum at a redshift of 0.200 (0.190-0.206; hereafter the quoted errors are 90%). The flux ratio in these lines corresponds to T e = 16 keV or a 90% lower limit of 12 keV, unambiguously confirming the presence of very hot gas in this cluster. The GIS spectrum in the 2.5-12 keV band shows a temperature of T e = 12.7 ± 2.0 keV, and an iron abundance of 0.38 ± 0.13, assuming isothermality. Comparison of the deconvolved GIS cluster images in the energy bands 2.5-7 keV and 7-12 keV (rest frame) shows considerable gas temperature variations in the central 3-4 core radii region. A similar kind of nonisothermality is independently indicated, although marginally, by SIS images in the narrow energy intervals which include the 6.67 keV and 6.97 keV iron line blends. The overall picture suggests that neither the galaxies (Soucail et al. 1994) nor even the gas in A2163 are in equilibrium, and we may be currently observing a merger. If the cluster gas is not isothermal, the somewhat too high temperature derived from the iron line ratio may require a higher iron abundance in the hotter regions of the gas.

AB - Preliminary results of the ASCA observation of A2163 are presented. Kα lines of He-like and H-like iron have been observed in the SIS spectrum at a redshift of 0.200 (0.190-0.206; hereafter the quoted errors are 90%). The flux ratio in these lines corresponds to T e = 16 keV or a 90% lower limit of 12 keV, unambiguously confirming the presence of very hot gas in this cluster. The GIS spectrum in the 2.5-12 keV band shows a temperature of T e = 12.7 ± 2.0 keV, and an iron abundance of 0.38 ± 0.13, assuming isothermality. Comparison of the deconvolved GIS cluster images in the energy bands 2.5-7 keV and 7-12 keV (rest frame) shows considerable gas temperature variations in the central 3-4 core radii region. A similar kind of nonisothermality is independently indicated, although marginally, by SIS images in the narrow energy intervals which include the 6.67 keV and 6.97 keV iron line blends. The overall picture suggests that neither the galaxies (Soucail et al. 1994) nor even the gas in A2163 are in equilibrium, and we may be currently observing a merger. If the cluster gas is not isothermal, the somewhat too high temperature derived from the iron line ratio may require a higher iron abundance in the hotter regions of the gas.

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Markevitch M, Yamashita K, Furuzawa A, Tawara Y. Nonisothermality of the hottest cluster abell 2163. Astrophysical Journal. 1994 Nov 20;436(1 PART 2).