Joint astrophysics nascent universe satellite: Utilizing GRBs as high redshift probes

The Joint Astrophysics Nascent Universe Satellite (JANUS) is a multiwavelength cosmology mission designed to address fundamental questions about the cosmic dawn. It has three primary science objectives: (1) measure the massive star formation rate over 5 ≤ z ≤ 12 by discovering and observing high-z gamma-ray bursts (GRBs) and their afterglows, (2) enable detailed studies of the history of reionization and metal enrichment in the early Universe, and (3) map the growth of the first supermassive black holes by discovering and observing the brightest quasars at z ≥ 6. A rapidly slewing spacecraft and three science instruments - the X-ray Coded Aperture Telescope (XCAT), the Near InfraRed Telescope (NIRT), and the GAmma-ray Transient Experiment for Students (GATES) - make-up the JANUS observatory and are responsible for realizing the three primary science objectives. The XCAT (0.5-20 keV) is a wide field of view instrument responsible for detecting and localizing 60 z ≥ 5 GRBs, including 8 z ≥ 8 GRBs, during a 2-year mission. The NIRT (0.7-1.7 μm) refines the GRB positions and provides rapid (30 min) redshift information to the astronomical community. Concurrently, the NIRT performs a 20; 000 deg2 survey of the extragalactic sky discovering and localizing 300 z ≥ 6 quasars, including 50 at z ≥ 7, over a two-year period. The GATES provides high-energy (15 keV -1:0 MeV) spectroscopy as well as 60-500 keV polarimetry of bright GRBs. Here we outline the JANUS instrumentation and the mission science motivations.