High Resolution X-ray Imaging after Chandra: The Generation-X Mission Concept
Martin Elvis (Harvard-Smithsonian CfA)
The sub-arcsecond imaging of Chandra has revolutionized X-ray astronomy and has had a great impact on astrophysics as a whole. With Chandra's angular resolution we can see far fainter sources leading to quantitative leaps in source numbers in e.g. star formation regions, galaxies and deep surveys, we can see qualitatively new structures in extended sources such as supernova remnants and clusters of galaxies showing us obvious signs of feedback from AGNs to cluster 'cool cores', and has extended singular objects into new classes of X-ray source, with the pulsar wind nebulae being a striking example.
A larger, high angular resolution, successor to Chandra will certainly be needed. Already the typical exposure time is nearly 1 day long, reflecting the small effective area Chandra supplies <1000cm^2. The challenge of making sub-arcsecond grazing incidence X-ray mirrors with far larger area than Chandra's, at reasonable cost, is daunting, and the planned new generation of X-ray missions contains nothing that approaches these properties.
This lack creates a yawning gap in future of astrophysics. X-rays give one of the few windows to observing the first stars, galaxies and black holes at z~10-20 and unique insights into extreme environments throughout the universe. While the powerful spectroscopy of Con-X addresses important classes of these environments, others require Chandra-like or better X-ray imaging.
We have been working to fill this gap. Using the lightweight Con-X mirrors as a starting point, we plan to combine them with active X-ray optics techniques now employed at synchrotrons world-wide to design an X-ray mission with 0.1 arcsecond HPD, and an area up to 100 square meters. This is Generation-X.