AAS 196th Meeting, June 2000
Session 34. A New Era in X-ray Astronomy
Topical Session Oral, Wednesday, June 7, 2000, 8:30-10:00am, 10:45am-12:30pm, 2:30-4:00pm, 4:15-6:00pm, Lilac Ballroom

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[34.11] Chandra Observations of Nearby Galaxies

A. H Prestwich (CXC)

Chandra has obtained high spatial resolution data on nearby galaxies showing a rich variety of X-ray sources in unprecedented detail. In this talk I will describe early Chandra observations of several diverse objects, focusing on starbursts (especially M82 and NGC3256), the nucleus of a ``normal'' spiral (M31) and a nearby AGN (Cen A).

The arcsecond spatial resolution of Chandra resolves the point source component from the extended emission in the prototype starburst M82. Several of the point sources are variable, and are identified as binaries for the first time. Approximately 50% of the hard X-ray flux is extended. I will describe how these observations shed light on the long-standing problem of the origin of the extended hard X-ray emission in starburst galaxies. The nuclear emission in the merging galaxy NGC3256 is resolved into two closely separated nuclei. These new data support a pure starburst origin for the total X-ray emission rather than a composite AGN/starburst, thereby making NGC3256 one of the most X-ray luminous starburst galaxies.

Observations of the nucleus of M31 resolves the nuclear source detected by ROSAT and Einstein into five point sources. One of these sources is coincident with the weak radio core, and may be associated with the super-massive black hole. The low luminosity and soft spectrum of this source poses a challenge to many black-hole emission mechanisms. The X-ray emission from the nearby radio galaxy Cen A shows many detailed components. Emission is seen from the radio jet, including a possible detection of the X-ray counter-jet. The nuclear source shows some evidence for spatial extent (0.2-0.3 arcsec). Many previously undetected point sources are seen in the HRC image of Cen A, including two transients. At least two point sources are associated with optical globular clusters.

The author(s) of this abstract have provided an email address for comments about the abstract: prestwich@cfa.harvard.edu

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