Astrophysics

Fermi GBM

STI Personnel: Dr. Bill Paciesas, Dr. Adam Goldstein, Mr. Bill Cleveland, Dr. Corinne Fletcher

The Fermi Gamma-ray Burst Monitor (GBM), operating in low-Earth orbit, continuously observes 2/3 of the sky in gamma rays.  It regularly detects cosmological gamma-ray bursts (GRBs) and disseminates rapid alerts to telescopes all over the world.  The joint detection of the binary neutron star merger GW170817 by GBM and the gravitational-wave detectors LIGO and Virgo in 2017 has led to an increased interest in GBM observations.  Over the last year, many improvements to operations have been made to better serve the broad interests of the community.  GBM now produces continuous data faster to the public, provides more accurate localizations of GRBs on the sky, and the GBM Team has improved the sensitivity of its sub-threshold searches, looking for weak GRB signals once the data has been downlinked to the ground.  The GBM Team, through a special data-sharing agreement with LIGO and Virgo, utilize these improved sub-threshold searches to look for signals in GBM data that correspond to weak signals in the gravitational-wave data.  The sub-threshold searches are also used to search for counterparts to astrophysical neutrinos, fast radio bursts, and very high energy transient alerts produced by other telescopes.

Chandra

STI Personnel:  Dr. Doug Swartz, Dr. Chien-Ting Chen, Dr. Linda Parker

IXPE

STI Personnel:  Dr. K. Kilaru, Dr. O. Roberts, Mr. J. Ranganathan

The Imaging X-ray Polarimetry Explorer (IXPE) is a Small Mission Explorer mission that exploits the polarization state of light from astrophysical sources, in order to provide an insightful understanding of X-ray production in objects such as neutron stars, pulsar wind nebulae, and stellar and supermassive black holes.  The optics are being made and calibrated at MSFC, with the X-ray polarization detectors being provided by the Italian Space Agency (ASI).  Other partners include the University of Colorado Boulder, Stanford University, McGill University, MIT and OHB Italia.  USRA contributions to this project include modeling, mirror module assembly, and support for the calibration of the mirror assembly.  It is currently slated for launch in 2021.

X-ray Astronomy Calibration and Test

STI Personnel:  Dr. K.Kilaru, Dr. O. Roberts

For decades, NASA and other agency missions have been using Wolter-I, grazing incidence optics for arcsecond resolution of astrophysical sources.  This is achieved by using unique hyperbolic and parabolic geometries to bring an image into focus (i.e., Chandra, XMM-Newton, etc).  For astrophysical applications, USRA scientists have been involved in the characterization and testing of X-ray mirrors for funded missions such as IXPE, and concept studies such as MiXO, MaGXIS and Lynx.  Ground-based applications have adopted this imaging technique by substituting the parabolic geometry with an elliptical one.  Such shells are being tested at MSFC by USRA for the National Ignition Facility and Sandia National Labs in order to image the Z-pinch regions in fusion reactions, with unprecedented resolution.  Other mirrors are also being developed for pioneering scientific applications, such as a neutron microscope at the National Institute for Standards and Technology.  These are just some of the many projects currently underway within the X-Astronomy group at USRA.  Research and development work runs in parallel to these projects, with an aim to achieve sub-arcsecond imaging capability for current and future, space- and ground-based applications alike.  Such research is being led by USRA through directed funding, including differential deposition and ion-milling.