March 30, 2007

Mission Scientist Report

Neil Gehrels INTEGRAL U.S. Mission Scientist

I have been a Mission Scientist since the beginning of the INTEGRAL mission and have been active with the mission since its first conception in the early 1990’s. My role is to coordinate with the US astrophysics community and to assist the ESA Project. Areas that I have contributed to include the Core Program definition, Target of Opportunity policies, review support, scientific utilization of INTEGRAL data and publicity of scientific results. As a Mission Scientist, I am receiving yearly funding from NASA adequate to support one postdoctoral scientist. In recent years, Dr. Volker Beckmann has been that person. Dr. Beckmann was previously a scientist at the INTEGRAL Science Data Centre in Geneva and is knowledgeable in the software and data archives of the INTEGRAL instrument. He has helped set up a highly capable mirror archive of INTEGRAL data for the US community at Goddard Space Flight Center. Since the mission inception, I have attended virtually all ISWT meetings and lately all User Committee meetings. I was on the subcommittee of the ISWT that designed the Core Program and have been actively supporting Project Scientist, Dr. Chris Winkler in Core Program updates. I believe INTEGRAL’s greatest legacy will come from the deep galactic plane observations achieved through the Core Program. Examples of discoveries from the Core Program are the population of heavily absorbed source in the galactic plane and the mapping of nucleosynthetic products along the plane. As Principal Investigator for the SWIFT Mission, I have worked with the INTEGRAL team to coordinate observations between the missions. SWIFT is highly complementary to INTEGRAL, offering sensitive X-ray and optical observations of sources detected by SPI and IBIS. It also has capability for rapid response to new transients and so provides multiwavelength follow-up of transients and GRBs. SWIFT, for example, has detected afterglow from 9 INTEGRAL GRBs. Another example is a current program of SWIFT X-ray and UV/optical observations of unidentified sources founded by IBIS. A huge scientific payoff is coming from these multi-wavelength , multi-mission observations. One of my activities is to support reviews of INTEGRAL in Europe and the US. There include mission extension reviews in ESA and the NASA Senior Review. INTEGRAL did quite well in the 2006 Senior Review, receiving full funding. The strong support by NASA is an indication of the international importance of this mission. A great deal of other science has come from collaborative work associated with my mission scientist position. For example, we produced a catalog of AGN observed with INTEGRAL. It was the first such catalog and had major implications for the fraction of absorbed Seyfert 2 AGNs in the hard X-ray sky. It was published in the Astrophysical Journal with Dr. Beckmann as the lead. Another example is the study of AGN with IBIS. We compiled a complete extragalactic sample based on IBIS observations of 25,000 square degrees to a limiting flux of 3x10^-11 ergs/cm^2/s in the 20 to 40 keV band. Using these data, we then constructed the first AGN luminosity function in this band and used it to study the evolution of AGNs. Other papers include those on the following: 1) blazar 3C 454.3 in outburst 2) the high energy spectrum of Seyfert NGC 4151 3) spectral studies of AGN NGC 4388 3) multi-mission observations of IGR J16283-4838,

This has been an exceptional period in the history of gamma-ray astronomy. With its combined capabilities in imaging and spectroscopy INTEGRAL is making huge contributions to the field. I am delighted to be involved in the mission as a Mission Scientist and look forward to many more fruitful years of participation.