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Chandra Observations of Starburst Galaxies M82 and NGC 3256

Published online by Cambridge University Press:  13 May 2016

Andrea Prestwich
Affiliation:
Smithsonian Astrophysical Observatory, 60 Garden St, Cambridge, MA, 02138, USA
Andreas Zezas
Affiliation:
Smithsonian Astrophysical Observatory, 60 Garden St, Cambridge, MA, 02138, USA
Philip Kaaret
Affiliation:
Smithsonian Astrophysical Observatory, 60 Garden St, Cambridge, MA, 02138, USA
Steve Murray
Affiliation:
Smithsonian Astrophysical Observatory, 60 Garden St, Cambridge, MA, 02138, USA
Roy Kilgard
Affiliation:
Smithsonian Astrophysical Observatory, 60 Garden St, Cambridge, MA, 02138, USA
Dong-Woo Kim
Affiliation:
Smithsonian Astrophysical Observatory, 60 Garden St, Cambridge, MA, 02138, USA
Eric Schlegel
Affiliation:
Smithsonian Astrophysical Observatory, 60 Garden St, Cambridge, MA, 02138, USA
Martin Ward
Affiliation:
Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH, UK
Paulina Lira
Affiliation:
Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH, UK

Abstract

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We present high resolution Chandra X-ray imaging of two starburst galaxies, M82 and NGC 3256. The central x-ray source observed by ROSAT and ASCA in M82 is resolved into 3 or 4 sources. Most of these sources are variable, suggesting that the point sources are powered by accretion. The brightest of these central sources is ∼ 1041ergs s−1 in the high state, and is responsible for the variability observed by ROSAT and ASCA. Assuming this source radiates at the Eddington limit, the mass is ∼ 500M. The diffuse hard (2-10 keV) emission in M82 is spatially coincident with diffuse radio emission and Pα. This is consistent with diffuse hard X-ray emission arising from hot thermal gas in the starburst region. Approximately 14 sources with LX > 1039ergs s−1 were detected in NGC 3256, including both nuclei. Two of these sources have LX > 1040ergs s−1. This observation suggests that “super Edington” sources may be preferentially associated with starburst galaxies (see also paper by Fabbiano in this volume)

Type
The Inner Regions of Galaxies
Copyright
Copyright © Astronomical Society of the Pacific 2001 

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