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NASA Goddard Space Flight Center Laboratory for High Energy Astrophysics Greenbelt, MD 20771 1 NASA Goddard Space Flight Center Laboratory for High Energy Astrophysics Greenbelt, MD 20771 This report covers the period from July 1, 2003 to June The following investigators are University of Maryland 30, 2004. Scientists ͑including UMBC͒: Drs. Keith Arnaud, David This Laboratory’s scientific research is directed toward Band, Simon Bandler, Volker Beckmann, Patricia Boyd, experimental and theoretical investigations in the areas of Gregory Brown, John Cannizzo, David Davis, Ian George, X-ray, gamma-ray, gravitational wave and cosmic-ray astro- Masaharu Hirayama, Una Hwang, Yasushi Ikebe, Naoko physics. The range of interests of the scientists includes the Iyomoto, Kip Kuntz, Mark Lindeman, Mike Loewenstein, Sun and the solar system, stellar objects, binary systems, Craig Markwardt, Julie McEnery, Paul McNamara, Igor neutron stars, black holes, the interstellar medium, normal Moskalenko, Chee Ng, Patric Palmeri, Dirk Petry, Christo- and active galaxies, galaxy clusters, cosmic ray particles, pher Reynolds, Ian Richardson, Jane Turner and Ken gravitational wave astrophysics, extragalactic background ra- Watanabe. diation, and cosmology. Scientists and engineers in the Visiting scientists from other institutions: Drs. Hilary Laboratory also serve the scientific community, including Cane ͑Univ. of Tasmania͒, Fred Finkbeiner ͑SSAI͒, Ralph project support such as acting as project scientists and pro- Fiorito ͑Catholic University͒, Hideyuki Fuke ͑KEK͒, Markos viding technical assistance for various space missions. Also Georganopoulos ͑NRC͒, Kenji Numata ͑NRC͒, Takashi at any one time, there are typically between ten and fifteen Okajima ͑JSPS͒, Randall Smith ͑JHU͒, Lev Titarchuk graduate students involved in Ph.D. research work in this ͑NRL͒, Allan Tylka ͑NRL͒, Tahir Yaqoob ͑JHU͒ and Tet- Laboratory. suya Yoshida ͑KEK͒. Other Support Scientists: Kevin Black ͑Forbin Scientific͒, 1. PERSONNEL Kazutami Misaki ͑JSPS͒, Robert Schaefer and Thomas ͑ ͒ Dr. Nicholas White is Chief of the Laboratory for High Stephens L3 . Energy Astrophysics. Dr. Neil Gehrels is Head of the Graduate Students doing their thesis research in this Gamma Ray, Cosmic Ray, & Gravitational Wave Astrophys- Laboratory are: from the U. of Maryland, Wayne Baumgart- ics Branch and Dr. Robert Petre is Head of the X-Ray As- ner, David Fiske, Derek Hullinger, Breno Imbiriba, Barbara trophysics Branch. Mattson, Sean McWilliams, Luis Reyes, David Wren and The civil service scientific staff includes: Drs. John Baker, Yuxuan Yang; from the University of Tokyo, Shinya Mat- Louis Barbier, Scott Barthelmy, Elihu Boldt, Kevin Boyce, suda; from USRP, Reynaldo Castro; from George Washing- Jordan Camp, Joan Centrella, Jean Cottam, Philip Deines- ton Univeristy, Alla Ibrahim and from GSFC John Sadleir. Jones, Enectali Figueroa-Feliciano, Keith Gendreau, Alice 2. RESEARCH PROGRAMS Harding, Robert Hartman, Stanley Hunter, Keith Jahoda, Frank Jones, Timothy Kallman, Demos Kazanas, Richard 2.1 Sun and Solar Systems Kelley, Caroline Kilbourne, Marvin Leventhal ͑retired scien- Drs. Reames and Ng studied the abundances of heavy tist͒, Francis Marshall, Stephen Merkowitz, John Mitchell, elements ͑33 Ͻ Z Ͻ 83͒ in solar energetic particles. Wave- Israel Moya, Richard Mushotzky, Jay Norris, Ann Parsons, particle interactions in solar flares cause large ͑_ 1000_ coro- Bill Pence, Scott Porter, Donald Reames ͑Emeritus͒, Steve nal͒ enhancements in these abundances in the accelerated Ritz, Peter Selemtsos, Robin Stebbins, Floyd Stecker, Robert particles, but no such enhancements are seen in particles ac- Streitmatter, Tod Strohmayer, Jean Swank, Bonnard Teegar- celerated at CME-driven shock waves. Dr. Reames published den, David Thompson, Jack Tueller, Tycho von Rosenvinge, a review of the variations in solar energetic particle events, Kim Weaver and William Zhang. including the evidence over the last 400 years seen in ice The following scientists are National Research Council cores. Associates: Drs. Peter Bloser, Jay Cummings, Jarek Dyks, Drs. Snowden and Kuntz with Dr. M. Collier ͑NASA/ Kenji Hamaguchi, Timothy Hamilton, Thomas Hams, Ma- GSFC LEP͒ observed solar wind charge exchange X-ray koto Sasaki, Alex Markowitz, James Van Meter, Tarek Saab, emission using the XMM-Newton observatory. The mission Philip Uttley and Anna Watts. likely originated from the sub-solar position of Earth’s mag- The following researchers are University Space Research netosheath and consisted of emission lines of highly ionized Association Scientists: Drs. Lorella Angelini, Zaven Arzou- oxygen, neon, magnesium, and probably carbon. The detec- manian, David Bertsch, Jerry Bonnell, Kai-Wing Chan, tion was serendipitous and the emission occurred during a Dae-Il Choi, Robin Corbet, Mike Corcoran, Ken Ebisawa, strong flux enhancement of the solar wind. This result sug- Georgia de Nolfo, Steve Drake, Illana Harrus, Stephen gests the utility of using such observations to map the struc- Henderson, Stephen Holland, Stefan Immler, Hans Krimm, ture of the geosphere/solar wind interface region in relatively John Krizmanic, John Lehan, Volker Leonhordt, Jim Loch- fine detail. ner, Alexander Moiseev, Koji Mukai, James Reeves, Chris Shrader, Steve Snowden, Yang Soong, Martin Still and Steve 2.2 Stars Sturner. The following scientists are SP Systems Scientists: Drs. During the past year Dr. Corcoran has continued studying Analia Cillis and Thomas Cline the X-ray emission from the supermassive star Eta Carinae. 2 ANNUAL REPORT In June 2003 Eta Carinae underwent an X-ray minimum, an coalescence time due to gravitational radiation is long ͑ϳ60 event that recurs every 5.5 years. During this time Dr. Cor- Gyr͒, so that this system’s discovery does not significantly coran monitored the X-ray brightness of Eta Carinae on a affect calculations of merger rates relevant to upcoming daily basis using the Rossi X-ray Timing Explorer and com- gravitational-wave instruments such as LIGO, but its evolu- municated these results via a website he maintained to other tionary history and potential for measurement of additional ground- and space-based observers. relativistic effects are being pursued. Drs. Hamaguchi and Corcoran are analyzing X-ray obser- Dr. Arzoumanian, with Drs. S. Safi-Harb ͑U. Manitoba͒, vations of Eta Car obtained with the XMM-Newton X-ray T. Landecker, and R. Kothes ͑NRC-HIA͒ reported the dis- Observatory, and Dr. Corcoran is collaborating with Dr. J. covery, in archival ROSAT and ASCA observations, of Pittard ͑Leeds͒ and Mr. D. Henley ͑Birmingham͒ on analysis X-ray emission from the direction of DA 495 ͑G65.7ϩ1.2͒,a of X-ray grating data obtained through the X-ray minimum likely supernova remnant of uncertain classification but with with the Chandra X-ray Observatory. similarities to the Crab Nebula. An unusual feature of the Drs. Corcoran, Hamaguchi, Gull ͑GSFC/LASP͒, Petre radio nebula is its annular morphology, with a flux minimum and Pittard along with Dr. K. Davidson ͑Minnesota͒, Dr. D. at the geometrical center. In the soft X-ray band, the ROSAT Hillier ͑Pittsburgh͒, Dr. N. Smith ͑Colorado͒, Dr. J. Morse data revealed a compact source near the edge of the central ͑Arizona͒, Dr. A. Damineli ͑Sao Paolo͒, Dr. N. Walborn radio ‘‘hole’’; the hard X-ray morphology, at the limit of ͑STScI͒, Dr. E. Verner and Mr. N. Collins ͑Catholic U.͒, Dr. ASCA’s angular resolution, is suggestive of extended emis- ͑ ͒ K. Weis and Dr. D. Bomans Ruhr-University of Bochum sion coincident with the ROSAT source. The X-ray flux was ͑ ͒ and Dr. Y. Butt CfA used a deep Chandra X-ray observa- found to be roughly constant with time, and its spectrum well tion during the X-ray minimum to reveal for the first time described by a power law with photon index ϳ1.7. Taken X-ray emission from the Homunculus Nebula surrounding together, this evidence suggests identification of the X-ray Eta Car. source with a magnetospherically active neutron star and its associated wind nebula. Timing analysis of the ASCA data 2.3 Pulsars and Magnetars yielded only a weak upper bound on pulsations with periods Ͼϳ Drs. A. Harding, A. Muslimov ͑Mantech Corp͒ and J. 30 ms. These results revealed for the first time the high- Dyks are developing a new model for particle acceleration energy engine that powers the DA 495 radio nebula, and high-energy emission from rotation-powered pulsars. strengthening its classification as a plerionic supernova rem- The slot gap model involves particle acceleration and high- nant, one that may represent the poorly explored late evolu- energy emission from the polar cap up to very high altitudes tionary stages of Crab-like nebulae. in the pulsar magnetosphere. Radiation from the slot gap can Dr. Arzoumanian, with Drs. W. Becker, and G. Kanbach produce profiles similar to those of observed gamma-ray pul- ͑Max Planck Inst.͒, M. Weisskopf, F. Elsner, A. Tennant, sars. The combination of a small emission solid angle with a and S. O’Dell ͑NASA MSFC͒, D. Lorimer ͑U. Manchester͒, high probability of viewing the emission predicts that more F. Camilo ͑Columbia U.͒, O. Reimer ͑Ruhr-Universitat͒ Bo- gamma-ray pulsars should be detectable at large distances. In chum, and D. Swartz ͑USRA/NASA MSFC͒, described a this picture, many of the EGRET unidentified sources are be multi-wavelength search for a counterpart to the brightest a radio-loud gamma-ray pulsar. unidentified gamma-ray source, 3EG J2020ϩ4017 in the Population synthesis studies of gamma ray and radio pul- G78.2ϩ2.1 supernova remnant. New X-ray and radio obser- sars in the Galaxy are being carried out by Drs. A. Harding vations of the gamma-Cygni field with the Chandra X-ray and P. Gonthier ͑Hope College͒. These studies are showing Observatory and the Green Bank Telescope were made, and that polar cap/slot gap models predict that radio-loud pulsars archival ROSAT data were re-analyzed. With Chandra it be- significantly outnumber radio-quiet gamma-ray pulsars, in came possible to measure the position of the putative X-ray contrast with outer gap models, which predict vastly more counterpart RX J2020.2ϩ4026 with sub-arcsec accuracy, radio-quiet pulsars.
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