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ASCA observation of NGC 4636: Dark matter and metallicity gradientWe present our analysis of ASCA PV phase observation of the elliptical galaxy NGC 4636. Solid state imaging spectrometer (SIS) spectra in six concentric annuli centered on NGC 4636 are used to derive temperature, metallicity, and column density profiles for the hot interstellar medium. Outside of the central 3 min the temperature is roughly constant at approximately 0.85 keV, while the metallicity decreases from greater than 0.36 solar at the center to less than 0.12 solar at R approximately 9 min. The implications of this gradient for elliptical galaxy formation and the enrichment of intracluster gas are discussed. We derive a detailed mass profile consistent with the stellar velocity dispersion and with ROSAT position sensitive proportional counter (PSPC) and ASCA SIS X-ray temperature profiles. We find that NGC 4636 becomes dark matter dominated at roughly the de Vaucouleurs radius, and, at r approximately 100 kpc, the ratio of dark to luminous matter density is approximately 80 and solar mass/solar luminosity approximately equal to 150. Evidence for the presence of a cooling flow is also discussed.
Document ID
19950036867
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Mushotzky, R. F.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Loewenstein, M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Awaki, H.
(Kyoto University Kyoto, Japan)
Makishima, K.
(University of Tokyo Tokyo, Japan)
Matsushita, K.
(University of Tokyo Tokyo, Japan)
Matsumoto, H.
(Kyoto University Kyoto, Japan)
Date Acquired
August 16, 2013
Publication Date
November 20, 1994
Publication Information
Publication: Astrophysical Journal, Part 2 - Letters
Volume: 436
Issue: 1
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A68466
Distribution Limits
Public
Copyright
Other

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