The Hot and Energetic Universe: The Wide Field Imager (WFI) for Athena+

TL;DR

The WFI instrument for Athena+ is a powerful wide-field X-ray imager designed for high sensitivity, resolution, and timing, enabling advanced surveys and observations of bright sources in the 0.1-15 keV band.

Contribution

This paper introduces the design, technology development, and baseline performance of the WFI instrument for Athena+, highlighting its capabilities for X-ray imaging and timing.

Findings

WFI offers a 40' to 50' field of view with high angular resolution.

It provides simultaneous imaging, spectroscopy, and timing in the 0.1-15 keV range.

The instrument surpasses current capabilities in X-ray survey performance.

Abstract

The Wide Field Imager (WFI) is one of the two scientific instruments proposed for the Athena+ X-ray observatory. It will provide imaging in the 0.1-15 keV band over a wide field, simultaneously with spectrally and time-resolved photon counting. The instrument is designed to make optimal use of the grasp (collecting area times solid angle product) provided by the optical design of the Athena+ mirror system (Willingale et al. 2013), by combining a sensitive approx. 40' diameter field of view (baseline; 50' goal) DEPFET detector with a pixel size properly sampling the angular resolution of 5 arc sec on-axis (half energy width).This synthesis makes the WFI a very powerful survey instrument, significantly surpassing currently existing capabilities (Nandra et al. 2013; Aird et al. 2013). In addition, the WFI will provide unprecedented simultaneous high-time resolution and high count rate capabilities for the observation of bright sources with low pile-up and high efficiency. In this paper, we summarize the instrument design, the status of the technology development, and the baseline performance.