Supernova Remnant Observations and Dark Matter Searches with Micro-X

Micro-X is a sounding rocket payload that combines an X-ray microcalorimeter with an imaging mirror to offer breakthrough science from high spectral resolution observations of extended X-ray sources. The design and development of this complicated payload has been an ongoing NASA APRA effort which is finally complete and undergoing integration in preparation for launch in February 2018. This three-year proposal seeks funding for: (1) Support of our NASA and NIST Co-I's for the first flight and for analysis of the flight 1 data, (2) design and implementation of payload modifications to optimize Micro-X for a dark matter search and the second flight of the payload from Australia in 2019, and (3) flight 2 data analysis. The scientific payload consists of a Transition Edge Sensor (TES) microcalorimeter array at the focus of a flight-proven conical imaging mirror. Micro-X capitalizes on three decades of NASA investment in the development of microcalorimeters and X-ray imaging optics. Micro-X offers a unique combination of bandpass, collecting area, and spectral and angular resolution. The spectral resolution goal across the 0.2-3.0 keV band is 4-8 eV Full-Width at Half Maximum (FWHM). A reconfiguration of the payload optimizing for “grasp” (Effective Area * Field of View) by removing the mirror and increasing the Field of View (FOV) allows this versatile sounding rocket payload to perform dark matter searches with world-leading sensitivity, as well as studies of the soft X-ray background. Our scientific program for this proposal will focus on supernova remnants (SNRs) and sterile neutrino dark matter. For flight 1, we will observe the Bright Eastern Knot (BEK) in the Puppis A SNR. The spatial extent of SNRs has made high-energy resolution observations with grating instruments extremely challenging. X-ray observations of SNRs with microcalorimeters will enable the study of the detailed atomic physics of the plasma; the determination of temperature, turbulence, and elemental abundances; and to look for evidence of charge exchange and clues to gamma-ray emmission from shock regions. We will continue to advance the technology readiness of TES microcalorimeters while enhancing the science capability of the payload by implementing a series of modifications for the second flight. This entails new higher-resolution detectors and modifications of the payload to allow it to fly without the mirror in a large FOV mode appropriate for dark matter searches and studies of the soft-X-ray background. These modifications for flight 2 enable a unique opportunity for a flight collaboration with the XQC sounding rocket team. The X-ray Quantum Calorimeter (XQC) payload is a wide FOV microcalorimeter spectrometer that has flown five times to study the soft diffuse X-ray background. Our two teams will collaborate on a joint observation campaign to take place from Australia in September 2019. The Galactic Center region is the target of Micro-X flight 2. This observation looks for an X-ray line from the decay of dark matter in the Milky Way. Sterile neutrinos with keV mass are theoretically well-motivated dark matter candidates with such a signal. In addition to a general search in the 1-10 keV band, Micro-X will investigate the presence of an observed X-ray line of unexplained origin at 3.5 keV from the Galactic Center. If it detects this line, Micro-X will be able to determine if its energy is consistent with that of known atomic lines in that energy range. In addition, its flux in the wider FOV of Micro-X can be compared with the XMM claim to help distinguish