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Title: CHANDRA AND HST STUDIES OF THE X-RAY SOURCES IN GALACTIC GLOBULAR CLUSTER M92

Abstract

We present the analysis of two observations of M92 taken with the Chandra X-Ray Observatory. We combined the two data sets with a total exposure of {approx}52 ks. With the combined observation, we detected 10 X-ray sources inside the half-mass radius (1.'02), five of which are inside the core radius (0.'26) of M92. The luminosities of the 10 sources are roughly within the range of 10{sup 30}-10{sup 32} erg s{sup -1} assuming cluster memberships. The background estimation suggests 7-8 cluster members and 2-3 background galaxies in M92. We identified the 10 sources by using Hubble Space Telescope Advanced Camera for Surveys observations of M92. Based on the X-ray and optical characteristics, we classified 4-5 possible candidates for cataclysmic variables within the half-mass radius. We discussed the possible formation mechanisms of the X-ray sources in M92 by comparing the predicted X-ray source number and observational results. Under the assumption that the number of X-ray sources scales with the encounter rate and the mass of the globular cluster, we expected eight X-ray sources formed from dynamical interactions and four from primordial binaries inside M92, which is consistent with the background estimation and comparable with the observational results. We therefore suggest that themore » X-ray sources in M92 may be contributed from both dynamical origin and primordial binaries.« less

Authors:
;  [1];  [2];  [3];  [4];  [5]
  1. Institute of Astronomy and Department of Physics, National Tsing Hua University, Taiwan (China)
  2. Astronomical Institute, Utrecht University, P.O. Box 80000, 3508 TA Utrecht (Netherlands)
  3. Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)
  4. Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States)
  5. Eureka Scientific, Inc., Austin, TX 78756 (United States)
Publication Date:
OSTI Identifier:
21578227
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 736; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/736/2/158; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COSMIC X-RAY SOURCES; GALAXIES; GALAXY CLUSTERS; LUMINOSITY; COSMIC RAY SOURCES; OPTICAL PROPERTIES; PHYSICAL PROPERTIES

Citation Formats

Lu, Ting-Ni, Kong, Albert K. H., Verbunt, Frank, Lewin, Walter H. G., Anderson, Scott F., and Pooley, David. CHANDRA AND HST STUDIES OF THE X-RAY SOURCES IN GALACTIC GLOBULAR CLUSTER M92. United States: N. p., 2011. Web. doi:10.1088/0004-637X/736/2/158.
Lu, Ting-Ni, Kong, Albert K. H., Verbunt, Frank, Lewin, Walter H. G., Anderson, Scott F., & Pooley, David. CHANDRA AND HST STUDIES OF THE X-RAY SOURCES IN GALACTIC GLOBULAR CLUSTER M92. United States. doi:10.1088/0004-637X/736/2/158.
Lu, Ting-Ni, Kong, Albert K. H., Verbunt, Frank, Lewin, Walter H. G., Anderson, Scott F., and Pooley, David. Mon . "CHANDRA AND HST STUDIES OF THE X-RAY SOURCES IN GALACTIC GLOBULAR CLUSTER M92". United States. doi:10.1088/0004-637X/736/2/158.
@article{osti_21578227,
title = {CHANDRA AND HST STUDIES OF THE X-RAY SOURCES IN GALACTIC GLOBULAR CLUSTER M92},
author = {Lu, Ting-Ni and Kong, Albert K. H. and Verbunt, Frank and Lewin, Walter H. G. and Anderson, Scott F. and Pooley, David},
abstractNote = {We present the analysis of two observations of M92 taken with the Chandra X-Ray Observatory. We combined the two data sets with a total exposure of {approx}52 ks. With the combined observation, we detected 10 X-ray sources inside the half-mass radius (1.'02), five of which are inside the core radius (0.'26) of M92. The luminosities of the 10 sources are roughly within the range of 10{sup 30}-10{sup 32} erg s{sup -1} assuming cluster memberships. The background estimation suggests 7-8 cluster members and 2-3 background galaxies in M92. We identified the 10 sources by using Hubble Space Telescope Advanced Camera for Surveys observations of M92. Based on the X-ray and optical characteristics, we classified 4-5 possible candidates for cataclysmic variables within the half-mass radius. We discussed the possible formation mechanisms of the X-ray sources in M92 by comparing the predicted X-ray source number and observational results. Under the assumption that the number of X-ray sources scales with the encounter rate and the mass of the globular cluster, we expected eight X-ray sources formed from dynamical interactions and four from primordial binaries inside M92, which is consistent with the background estimation and comparable with the observational results. We therefore suggest that the X-ray sources in M92 may be contributed from both dynamical origin and primordial binaries.},
doi = {10.1088/0004-637X/736/2/158},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 736,
place = {United States},
year = {2011},
month = {8}
}