The JANUS X-Ray Flash Monitor

TL;DR

The JANUS mission aims to detect high-redshift gamma-ray bursts and X-ray flashes using the XRFM instrument to explore early universe star formation and reionization, with a wide field of view and rapid response capabilities.

Contribution

This paper presents the design and science goals of the XRFM instrument on the JANUS mission, focusing on its ability to detect high-redshift XRFs and GRBs.

Findings

Designed to detect XRFs/GRBs in 1-20 keV range

Wide field of view of 4 steradians

Sensitivity to flux above 240 mCrab

Abstract

JANUS is a NASA small explorer class mission which just completed phase A and was intended for a 2013 launch date. The primary science goals of JANUS are to use high redshift (6<z<12) gamma ray bursts and quasars to explore the formation history of the first stars in the early universe and to study contributions to reionization. The X-Ray Flash Monitor (XRFM) and the Near-IR Telescope (NIRT) are the two primary instruments on JANUS. XRFM has been designed to detect bright X-ray flashes (XRFs) and gamma ray bursts (GRBs) in the 1-20 keV energy band over a wide field of view (4 steradians), thus facilitating the detection of z>6 XRFs/GRBs, which can be further studied by other instruments. XRFM would use a coded mask aperture design with hybrid CMOS Si detectors. It would be sensitive to XRFs/GRBs with flux in excess of approximately 240 mCrab. The spacecraft is designed to rapidly slew to source positions following a GRB trigger from XRFM. XRFM instrument design parameters and science goals are presented in this paper.