2006ApJ...642..759B -
Astrophys. J., 642, 759-764 (2006/May-2)
The size of the cooling region of hot gas in two elliptical galaxies.
BREGMAN J.N., OTTE B., MILLER E.D. and IRWIN J.A.
Abstract (from CDS):
Some early-type galaxies show O VI emission, a tracer of gas at 105.5 K, and a predicted product of gas cooling from the X-ray-emitting temperatures. We studied the spatial extent and velocity structure of this cooling gas by obtaining spectra of the O VI doublet in NGC 4636 and NGC 5846 with the Far Ultraviolet Spectroscopic Explorer. For NGC 4636, the central LWRS pointing shows that the O VI lines are double-peaked and symmetrical about the systemic velocity of the galaxy, with a separation of 210 km/s. An LWRS observation 30'' from the center failed to show additional O VI emission. For NGC 5846, three spectra were obtained with 4''x20'' apertures (MDRS) at the center and 4'' to the east and west of the center. The O VI line flux seen in the previous LWRS is contained in the sum of the smaller apertures, with most of the flux in a single noncentral MDRS aperture, suggesting a size for the emission ≤0.5 kpc; the emission consists of a blue and red peak. For both galaxies, the O VI velocity structure is similar to that of the optical [N II] emission and is consistent with rotation. The compactness and velocity structure of the O VI emission rules out cooling flow models with broadly distributed mass dropout but is consistent with cooling flow models in which the cooling occurs primarily in the central region. The 104 K gas may be the end state of the O VI emitting gas.
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Journal keyword(s):
Galaxies: Cooling Flows - Galaxies: Individual: NGC Number: NGC 4636 - Galaxies: Individual: NGC Number: NGC 5846 - Galaxies: ISM - X-Rays: Galaxies
Simbad objects:
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