Symposium Proceedings

AGN interaction with host galaxy

The talks are in the same order as the Program Schedule.


A Deep Chandra Observation of Centaurus A

Ralph Kraft (SAO) , R. Kraft (SAO), M. Hardcastle (University of Hertfordshire), A. Jordan (ESO), G. Sivakoff (Ohio State University), D. Evans (Harvard University), J. Croston (University of Hertfordshire), W. Forman (SAO), C. Jones (SAO), P. Nulsen (SAO), S. Murray (SAO), D. Worrall (University of Bristol), M. Birkinshaw (University of Bristol), C. Sarazin (University of Virginia), A. Juett (University of Virginia), S. Raychaudhury (Birmingham University), N. Brassington (SAO), W. Harris (McMaster University), K. Woodley (McMaster University)

We present preliminary results from deep (6 x 100 ks) Chandra VLP observations of the nearby (d=3.8 Mpc, 1''=18.4 pc) galaxy Centaurus A. Cen A is the nearest early-type galaxy, late stage merger, and radio galaxy; our deep observations probe a wide range of astrophysically interesting phenomena unobservable in any other galaxy. In particular, we will discuss the temperature and abundance profile of the ISM, the GC/LMXB connection, the spectral and temporal properties of the XRB population (including one previously unknown ULX transient, and several others with LX>1E38 ergs s-1 ), the role that the ongoing nuclear outburst plays in heating the ISM and in transporting high abundance material from the galaxy center to the halo, and the spatial and spectral morphology of the X-ray jet. The ISM exhibits a complex temperature and abundance profile, with mixing of gas likely due to both the merger and the radio outburst. We have extensive HST/ACS data on the globular cluster population as well, the proximity of Cen A permits us to measure the structural parameters (i.e. core radii, central densities, etc.) of the GCs to better understand the LMXB/GC link. The energy loss scale for X-ray synchrotron emission in extragalactic jets is only tens of pc. Cen A is the only extragalactic jet for which Chandra's spatial probes this scale.

[PDF of the talk]

Modeling the Supermassive Black Hole Driven Shocks in M87

William Forman (SAO) , C. Jones (SAO), E. Churazov (MPA, IKI), R. Kraft (SAO), M. Markevitch (SAO), P.Nulsen (SAO), J.Eilek (NMT), F. Owen (NRAO)

We have modeled the shocks detected in the 500ksec Chandra observation of M87 using a hydrodynamic model of the gas surrounding M87. Starting from a description of the unperturbed gas density and gas temperature distributions derived from deprojections, we parameterize the outbursts that produce the observed shocks. For the observed shocks, we derive the outburst energy, the outburst age, and the duration of the outburst. For the outburst that gave rise to the main 13kpc ring, we constrain the duration of the outburst to more than a few million years. Finally, with a simple model for the main outburst, we can estimate the fraction of energy deposited in M87's atmosphere and the fraction that is carried away by the weak shock. We show that the deposited energy is comparable to that radiated by M87's cooling atmosphere.

[PDF of the talk]

The unusual X-ray morphology of NGC 4636: cavities, off-center outbursts and shocks revealed by deep Chandra observations

Alessandro Baldi (Harvard-Smithsonian CfA) , W. Forman (Harvard-Smithsonian CfA), C. Jones (Harvard-Smithsonian CfA), R. Kraft (Harvard-Smithsonian CfA), P. Nulsen (Harvard-Smithsonian CfA), L. David (Harvard-Smithsonian CfA)

We present the analysis of 200 ksec of Chandra observations of the X-ray luminous elliptical galaxy NGC 4636, located in the outskirts of the Virgo cluster. A soft band (0.5-2 keV) image confirms the presence of a bright core in the center surrounded by an extended X-ray halo and two prominent, quasi-symmetric, 8 kpc long, arm-like features. In addition, faint structures, possibly cavities, are visible outside the core suggesting a more complex history than previous observations. We present surface brightness and temperature profiles of these structures. We show that the edges of at least three of these features are sharp and are characterized by temperature jumps of about 20-25

[PDF of the talk]

How Luminous Was the Galactic Supermassive Black Hole in the Past?

Frederick Baganoff (MIT Kavli Institute) , M. P. Muno (Caltech), W. N. Brandt (Penn State), S. Park (Penn State), and M. R. Morris (UCLA)

Repeated deep Chandra monitoring of Sgr A* over the past few years has revealed rapidly variable Fe fluorescence features within 6' (14 pc) of the supermassive black hole, suggesting that its X-ray luminosity may have been greater than 10^38 erg/s for at least 2-3 years about 60 years ago, before the first X-ray satellites were launched. These results will be discussed in the context of Chandra observations of Fe fluorescence in Sgr B2 and Sgr C, and arguments will be presented against the alternative hypotheses of irradiation by local X-ray binaries or excitation by low-energy cosmic ray electrons.