The Warm-Hot Intergalactic Medium Explorer (WHIMex) mission

Abstract

Web. WHIMx wi1 tect absoxltih lines in the higJ-density filaments of the Cosmic Web. ABSTRACTThe WHIMex X-ray observatory will provide an order of magnitude improvement in sensitivity and spectroscopic resolution, ushering in a new era in astrophysics. With resolution 4,000 and collecting area 250 cm 2 in the 0.2-0.8 keV band, WHIMex will greatly extend the spectroscopic discoveries of Chandra and XMM with a low-cost, highly-productive Explorer mission. WHIMex's spectra will provide a wealth of new information on the physical conditions of baryonic matter from the local regions of our Galaxy out to the Cosmic Web and the large-scale structures of the Universe. This baryonic matter is thought to result from gravitational collapse of moderately overdense, dark-matter filaments of the Cosmic Web. The chemical enrichment of the Cosmic Web appears to arise from galactic super winds and early generations of massive stars. WHIMex will test these theories, distinguish between competing models, and provide new insights into galaxy evolution and the structure of the universe High-resolution X-ray spectroscopy was identified by the ASTRO 2010 decadal survey as a high-priority capability in the coming decade for a wide variety of science goals. Unfortunately, no other planned mission can address this science until IXO flies, no earlier than the late 2020s. WHIMex achieves its high level of performance in a single-instrument, affordable package using X-ray optical technologies developed for IXO and NuSTAR by academic, industrial and government research centers. The technology readiness levels of all the components are high. We plan to build an optical test module and raise the optical system readiness to TRL 6 during Phase A.

Performance Testing of a Large-Format X-ray Reflection Grating Prototype for a Suborbital Rocket Payload

“…By combining these two properties, reflection gratings operated in the extreme off-plane mount are capable of both high spectral resolution and high diffraction efficiency in the soft X-ray bandpass. Reflection gratings operated in this diffraction geometry have heritage on several proposed highresolution soft X-ray spectroscopy missions (Bookbinder et al, 2008;Lillie et al, 2011;White et al, 2010). In addition to these proposed missions, these reflection gratings will be implemented on the OGRE soft X-ray grating spectrometer (Tutt et al, 2018;Donovan et al, , 2019.…”

Fabrication and testing of off-plane gratings for future X-ray spectroscopy missions

“…However, silicon foundaries are typically only capable of realizing off-axis cuts of < 10°, well below the blaze angles proposed for notional off-plane X-ray spectrographs. By way of an example, the Off-Plane Grating Rocket Experiment (OGRE) proposes to use gratings with a 29.5°blaze 3 . By using other commercially available crystallographic orientations of silicon, however, a variety of blaze angles can be obtained.…”

“…Building soft X-ray spectrometers capable of simultaneously achieving high resolution and high throughput is an ongoing challenge to the X-ray instrumentation community. Successfully answering this challenge requires the study of a variety of concept missions ( [1], [2], [3], [4]) to understand the scientific and budgetary impact of possible missions, as well as a program of technology development to retire risk and assess the performance of the incorporated technologies.…”

“…3 gives an overview of the EBL process resulting in a blazed off-plane grating. In the same fashion as the T-NIL technique, a silicon wafer of the desired crystallographic orientation is coated with process layers of SiN x and EBL resist…”

“…3 shows the diffraction geometry of the test configuration for Grating 1.The groove facets of Grating 1 were blazed toward negative orders. A graze angle of g = 1.5°was chosen to be identical to the graze angle for Arcus and OGRE.…”