Time Urgency

Obtaining these spectra early in the mission is critical to having benchmarked models for extended sources by the second year of the mission. An immediate goal of the X-ray Emission Line Project would be to identify spectral bands that appear to agree or not agree with the models. This information could be used to exclude problematic spectral regions in a systematic way. We will maximize efforts to improve the models with new theoretical calculations or targetted atomic physics experiments by producing the spectra early, making the data public immediately, and facilitating communication and collaboration with the atomic and plasma physics communities. Both Nancy Brickhouse and Jeremy Drake have established collaborations in these areas and are in regular communication on atomic physics and modeling issues with other experts in the field.

We propose that line identifications, comparisons with predictions, and information about problematic spectral regions will be available by the AO2 date of March 1999, five months after the beginning of AXAF science operations (and only two months after GO observations begin).

We have, of course, considered the possibility of applying for these observations through the Guest Observer program. Not only would this delay the process, but the chances for success on the grounds we have listed above may not be that good. Most proposals are judged on the basis of their astrophysical science, not on their atomic physics. The support of the AXAF Science Center at this crucial stage may ultimately improve the chances for success of basic plasma modeling proposals, but we first need to demonstrate the value of benchmarking.

We understand that some of these targets are popular targets on the Guaranteed Time Observer lists as well. There is the possibility that GTO's may want to pool time for these sources, but still maintain proprietary rights within the expanded collaboration. While we would prefer that the data be taken during calibration and that it be public, an alternative is that we be included as collaborators with the GTO's. We are keen to collaborate on the X-ray Emission Line Project; however, proprietary concerns might delay the distribution of the products. Furthermore, our ability to involve collaborators beyond the ASC would be potentially compromised. Thus we strongly believe the AXAF Science Center should lead this project as a public service, and encourage a cooperative effort to improve the modeling through immediate public distribution.

References