AXTAR: Mission Design Concept

TL;DR

AXTAR is a proposed X-ray mission designed for high time resolution observations of compact objects, offering large effective area and rapid response capabilities to study extreme physics near neutron stars and black holes.

Contribution

The paper introduces the AXTAR mission concept, highlighting its innovative large-area X-ray timing instrument and its potential to significantly advance high time resolution astrophysics.

Findings

AXTAR's Large Area Timing Array offers 7-36 times the effective area of RXTE PCA.

The mission concept includes a Sky Monitor for transient detection and rapid follow-up.

Preliminary design results demonstrate feasibility and scientific potential.

Abstract

The Advanced X-ray Timing Array (AXTAR) is a mission concept for X-ray timing of compact objects that combines very large collecting area, broadband spectral coverage, high time resolution, highly flexible scheduling, and an ability to respond promptly to time-critical targets of opportunity. It is optimized for submillisecond timing of bright Galactic X-ray sources in order to study phenomena at the natural time scales of neutron star surfaces and black hole event horizons, thus probing the physics of ultradense matter, strongly curved spacetimes, and intense magnetic fields. AXTAR's main instrument, the Large Area Timing Array (LATA) is a collimated instrument with 2-50 keV coverage and over 3 square meters effective area. The LATA is made up of an array of supermodules that house 2-mm thick silicon pixel detectors. AXTAR will provide a significant improvement in effective area (a factor of 7 at 4 keV and a factor of 36 at 30 keV) over the RXTE PCA. AXTAR will also carry a sensitive Sky Monitor (SM) that acts as a trigger for pointed observations of X-ray transients in addition to providing high duty cycle monitoring of the X-ray sky. We review the science goals and technical concept for AXTAR and present results from a preliminary mission design study.