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Search for Coronal Emission Lines in Cooling Flow Clusters with the Keck 10 Meter Telescope

Yan, L. and Cohen, J. G. (1995) Search for Coronal Emission Lines in Cooling Flow Clusters with the Keck 10 Meter Telescope. Astrophysical Journal, 454 . pp. 44-49. ISSN 0004-637X. doi:10.1086/176462.

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Using the Low Resolution Imaging Spectrograph on the Keck 10 m telescope, we have searched for the coronal emission line [Fe X] 6374 Å produced by the gas at temperatures of 105 106 K in the central several 10 kpc regions of two massive cooling flow clusters: Abell 1795 and PKS 0745-191. We did not detect an significant [Fe X] 6374 Å emission in either cluster. The 1 σ surface brightness limits for the [Fe X] 6374 Å line in the central 75 h^(-1)_(50) kpc region of Abell 1795 and in the central 30 h^(-1)_(50) kpc region of PKS 0745-191 are 10^(-18) ergs s^(-1) cm^(-2) arcsec^(-2) and 7 × 10^(-19) ergs s^(-1) cm^(-2) arcsec^(-2), respectively. Our upper limits of the [Fe X] 6374 Å surface brightness in both clusters are about a factor of 10 better than the previous measurements. These results are consistent with the theoretically predicted [Fe X] 6374 Å surface brightness by the popular inhomogeneous models (Sarazin & Graney 1991), in which gas cools out of the flow at a range of radii, leaving the hot gas distributed as r. The upper limits on mass cooling rate derived from our measurement are also consistent with the cooling rates derived from X-ray data for these two clusters. Our results are contradictory to the claimed significant detection in Abell 1795 by Anton et al. (1991) and the 3 σ marginal detection in PKS 0745-191 reported by Donahue & Stocke (1994). In addition, we also measured upper limits on the [Fe X]/Hα ratio in both clusters, which provide strong constraints on various theoretical models of nebulae heating for production of the luminous low-ionization emission lines by cool (˜10^4 K) nebular filaments. The [Fe X]/Hα (R < 15 kpc) ratios in Abell 1795 and PKS 0745 - 191 are less than 0.6% and 0.13%, respectively.

Item Type:Article
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URLURL TypeDescription
Yan, L.0000-0003-1710-9339
Cohen, J. G.0000-0002-8039-4673
Additional Information:© American Astronomical Society • Provided by the NASA Astrophysics Data System. Received 1995 March 15; accepted 1995 May 31. The W. M. Keck Observatory is a scientific partnership between the California Institute of Technology and the University of California. It was made possible by the generous and visionary gift by the W. M. Keck foundation, and the support of its president, Howard Keck. It is a pleasure to thank the observing assistants T. Chelminiak and B. Schaefer for their expert work during the observing runs. We wish to thank Megan Donahue for the useful discussions and her constructive suggestions, which have helped us to improve the paper.
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W. M. Keck FoundationUNSPECIFIED
Subject Keywords:cooling flows - galaxies: clusters: general
Record Number:CaltechAUTHORS:20190603-153225338
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96090
Deposited By: George Porter
Deposited On:04 Jun 2019 21:40
Last Modified:16 Nov 2021 17:17

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