1. Centaurus A Kraft, Hardcastle, Croston, Worrall, Birkinshaw, Nulsen, Forman, Murray, Goodger, Sivakoff,Evans, Sarazin, Harris, Gilfanov, Jones X-ray composite image Jet Southwest Inner Lobe Northern Middle Lobe Hot ISM

2. Centaurus A – the Nearest Radio Galaxy Kraft et al. 2000, 2001, 2003, 2007, 2008 Hardcastle et al. 2003, 2008 Worrall et al. 2008 Chandra VLA

3. Multiple Outbursts in Cen A Series of outbursts seen in the radio (Ekers/Burns, Morganti et al.) Nuclear jet Inner lobes Northern middle lobe Linear size to 250 kpc Repeated AGN outbursts spanning 10 9 yrs

4. Centaurus A – Bubbles and Jets Distance 3.7 Mpc 1” ~ 18 pc New deep (600 ksec) Chandra observation -- PI R. Kraft Diffuse emission HOT ISM – kT=0.4 keV, Jet, counter-jet, Lobes, Absorption lanes Bubble diameter ~ 3 kpc

5. Centaurus A Radio (blue) Chandra X-ray (red) Lifetime of synchrotron emission of the ultrarelativistic particles is much less than the travel time down the jet. (in inner jet ~20 years, ~60 years beyond knot B). How is kinetic energy of jets transferred into internal energy of relativistic plasma in jets? Jet spans 4.5 kpc from nucleus to northern lobe and expands with distance from the nucleus

6. Centaurus A Jet Radio (blue) Chandra X-ray (red) nucleus Following M87 jet results where knots are identified as sites of shocks where magnetic fields are compressed and particles accelerated (Sparks et al. Perlman et al.), Cen A knots may play same role in accelerating particles (Kraft et al., Hardcastle et al., Worrall et al.) Note: Gaps between groupings of knots with only diffuse synchrotron emission. Particle acceleration distributed throughout jet. Extended compact knots - Lx (knots) ~ 10 39 erg/s ~1/3 jet Lx within 1’, 2/3 jet Lx is in knots.

7. The Jet in Centaurus A Differences between positions of radio and X-ray knots explained by particle aging. Many X-ray (blue) knots correspond to radio (red) knots (Hardcastle et al.2003).

8. The Inner Region of the Cen A Jet Chandra ( blue ) and VLA (red 8.4 GHz) observations (Hardcastle et al 2003) Faint, well- collimated inner jet region detected. In standard FRI sources, this region is where efficient, supersonic flow transports energy up to where jet flares and becomes turbulent. Could have in situ particle acceleration here.

9. Centaurus A – Bubbles and Jets Counter-jet - several X-ray features with radio counterparts (Hardcastle et al ) Southern lobe - sharp, smooth Bubble diameter 3 kpc

10. Centaurus A - Southwest Radio Lobe Old view -- Emission in shell is from gas swept up by expanding lobe Model X-ray bubble as driven by expansion of radio plasma Gas temperature in lobe ~2.9 keV (in ISM kT = 0.3 keV) Shell gas density 2 10 -2 cm -3 (In ISM ~ 2 10 -3 cm -3 ) Shell overpressured (2 10 -10 dyn cm -2 ; in ISM ~10 -12, in lobe ~10 -11 ) Bubble expanding supersonically at Mach 8.5 (2400 km/sec)

11. Centaurus A - Southwest Radio Lobe But there were problems with this model ! 1)Density drop was too large compared to temperature change across shock. Inconsistent Mach numbers for shock velocity, 2)The gas density in shell was too high for swept up ISM 3)Deep Chandra spectra show southwest region of shell is synchrotron and most likely not thermal emission (upper region of shell is well fit with thermal spectrum).

12. Chandra images of Cen A lobes with radio contours New view -- Southwest X-ray lobe is synchrotron emission! (NE shell??)

13. The Northern Middle Lobe in Cen A Series of outbursts seen in the radio (Ekers/Burns also see Morganti et al.) Nuclear jet Inner lobe Northern middle lobe Linear size to 250 kpc

14. Centaurus A X-ray filament/knots on edge of NRL radio emission - X-ray knots not correlated with radio emission Northern middle lobe - poster by Kraft et al. Previous work - Feigelson et al 1981 (Einstein), Morini et al 1989 (EXOSAT), Morganti et al 1999 (ASCA).. XMM-Newton and Morganti et al (yellow) Burns et al (green) radio countours

15. Centaurus A - Northern Middle Lobe XMM-Newton MOS 0.5-2 keV smoothed, exposure corrected. Extended X-ray knots in filament of diffuse emission Knots are thermal (kT ~ 0.5 keV); L X (N1) ~10 39 ergs/s XMM-Newton MOS 0.5-2 keV “raw” image

16. Centarus A - Northern Middle Lobe. XMM-Newton MOS Extended KNOTS are overpressured (and short-lived ~3 10 6 yrs). Must have been recently shock-heated by jet. NML still being powered by current AGN outburst.

17. Centaurus A - Hot ISM Surface brightness discontinuity ~3.5 kpc from nucleus Gas motions in the hot ISM produced by the recent merger (Kraft et al. 2008 arXiv:0803.3595) Chandra 0.5-1 keV

18. Centaurus A conclusions Much of emission from SW lobe is synchrotron In jet, knots may play important reacceleration role. NML still powered by jetSloshing of hot gas caused by merger

19. Thanks