Arcus: an ISS-attached high-resolution x-ray grating spectrometer

Abstract

We present the design and scientific motivation for Arcus, an X-ray grating spectrometer mission to be deployed on the International Space Station. This mission will observe structure formation at and beyond the edges of clusters and galaxies, feedback from supermassive black holes, the structure of the interstellar medium and the formation and evolution of stars. The mission requirements will be R>2500 and >600 cm 2 of effective area at the crucial O VII and O VIII lines, values similar to the goals of the IXO X-ray Grating Spectrometer. The full bandpass will range from 8-52Å (0.25-1.5 keV), with an overall minimum resolution of 1300 and effective area >150 cm 2 . We will use the silicon pore optics developed at cosine Research and proposed for ESA's Athena mission, paired with off-plane gratings being developed at the University of Iowa and combined with MIT/Lincoln Labs CCDs. This mission achieves key science goals of the New Worlds, New Horizons Decadal survey while making effective use of the International Space Station (ISS).

In-flight performance of the Canadian Astro-H Metrology System

“…A similar alignment system [8][9][10] is used on the NuSTAR satellite and it will continue to be required for several upcoming missions [11][12][13] in x-ray astronomy.…”

Strategies for detecting the missing hot baryons in the universe

“…When one takes into account the change in effective area of a typical mirror-instrument combination, the situation worsens. Here we use the Arcus effective area, 33 although we would obtain about the same result when using the Athena microcalorimeter (X-IFU) response. 38 The effective area decreases with decreasing energy, and when combined with Galactic absorption, leads to a loss of throughput by a factor of four at 0.315 keV, which corresponds to redshifts of 0.83 and 1.08 for O VII and O VIII.…”

“…The spectral resolution of the XMM-Newton RGS and Chandra LETG is about 360-440 for the O VII and O VIII lines at z = 0, and with collecting areas is 43 cm 2 and 3 cm 2 (see Table 1 for a listing of related instrumental properties along with those considered here). Within the typical cost of previous NASA Explorer and Probe class missions, it is possible to obtain a spectral resolution of about 3000, 33 which is about the Doppler width of the lines, and a collecting area that approaches 1000 cm 2 . Together, these provide more than an order of magnitude improvement in line detectability.…”

Line spread functions of blazed off-plane gratings operated in the Littrow mounting

“…Arcus, for example, is a proposed X-ray grating spectrometer to be mounted on the International Space Station requiring resolution R (λ/∆λ) > 2000 and effective area > 400 cm 2 over the 21.6 -25Å bandpass in order to perform its critical science. 1 This represents a substantial improvement in both metrics over currently existing capabilities, and will require significant investment in enabling technologies. Off-plane reflection gratings are one such enabling technology, offering the ability to work at high dispersion while maintaining excellent throughput.…”