Science Driven Arguments for a 10 Sq.meter, 1 Arcsecond X-ray Telescope

X-ray astronomy needs to set bold, science driven goals for the next decade. Only with defined science goals can we know what to work on, and a funding agency appreciate the need for significant technology developments. To be a forefront science the scale of advance must be 2 decades of sensitivity per decade of time. To be stable to new discoveries these should be general, discovery space, goals. A detailed consideration of science goals leads us to propose that a mirror collecting area of 10 sq.meters with arcsecond resolution, good field of view (>10 arcmin), and with high spectral resolution spectroscopy (R=1000-10,000) defines the proper goal. This is about 100 times AXAF, or 30 times XMM. This workshop has shown that this goal is only a reasonable stretch from existing concepts, and may be insufficiently bold. An investment of ∼$ 10M/year for 5 years in X-ray optics technologies, comparable to NASA’s investment in ASTRO-E or a SMEX, is needed, and would pay off hugely more than any small X-ray mission. 1. Long Term Goals for X-ray Astronomy Any big undertaking, such as X-ray astronomy 1 surely is, must set long range goals. With clear long-term science goals in place we can see which developments are essential, and which are mere sidelines amusing, but dead ends. Daniel Goldin, the NASA Administrator, urged astronomers (San Antonio AAS meeting, January 1996) to make decade length plans, even if the plan changes in a few years time. This is what we do here. The goals we shall describe are deliberately ambitious. We propose that Xray astronomers should aim to reach sensitivities 100 times beyond AXAF, while retaining high angular resolution and achieving high dispersion spectroscopy (Table 1) 2 . This does not mean that the very next mission we design should necessarily have all these capabilities. Nor does it rule out smaller missions with different goals. It does mean that the next major mission we design should at least be a deliberate and significant step toward these capabilities. To some 1 We discuss only the standard 0.1-10 keV band of X-ray astronomy, in which grazing incidence optics work efficiently. 2 These numbers describe quite well Hale’s Mt.Wilson 100-inch telescope (Osterbrock 1995), so we are suggesting that X-ray astronomy try to equal the state of optical astronomy in 1917.