A Chandra observation of the X-ray environment and jet of 3C 31 |
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Authors: | M J Hardcastle D M Worrall M Birkinshaw R A Laing A H Bridle |
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Institution: | Department of Physics, University of Bristol, Tyndall Avenue, Bristol BS8 1TL; Space Science and Technology Department, CLRC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX; University of Oxford, Department of Astrophysics, Nuclear and Astrophysics Laboratory, Keble Road, Oxford OX1 3RH; National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475, USA |
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Abstract: | We have used a deep Chandra observation of the central regions of the twin-jet Fanaroff–Riley class I (FRI) radio galaxy 3C 31 to resolve the thermal X-ray emission in the central few kpc of the host galaxy, NGC 383, where the jets are thought to be decelerating rapidly. This allows us to make high-precision measurements of the density, temperature and pressure distributions in this region, and to show that the X-ray emitting gas in the centre of the galaxy has a cooling time of only 5×107 yr . In a companion paper, these measurements are used to place constraints on models of the jet dynamics. A previously unknown one-sided X-ray jet in 3C 31, extending up to 8 arcsec from the nucleus, is detected and resolved. Its structure and steep X-ray spectrum are similar to those of X-ray jets known in other FRI sources, and we attribute the radiation to synchrotron emission from a high-energy population of electrons. In situ particle acceleration is required in the region of the jet where bulk deceleration is taking place. We also present X-ray spectra and luminosities of the galaxies in the Arp 331 chain of which NGC 383 is a member. The spectrum and spatial properties of the nearby bright X-ray source 1E 0104+3153 are used to argue that the soft X-ray emission is mostly due to a foreground group of galaxies rather than to the background broad absorption-line quasar. |
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Keywords: | radiation mechanisms: non-thermal galaxies: active galaxies: individual: 3C 31 galaxies: jets X-rays: galaxies |
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