Einstein Probe — a small mission to monitor and explore the dynamic X-ray Universe

Abstract

Einstein Probe is a small mission dedicated to time-domain high-energy astrophysics. Its primary goals are to discover high-energy transients and to monitor variable objects in the 0.5-4 keV Xrays, at higher sensitivity by one order of magnitude than those of the ones currently in orbit. Its wide-field imaging capability, featuring a large instantaneous field-of-view (60 • × 60 • , ∼ 1.1 sr), is achieved by using established technology of micro-pore (MPO) lobster-eye optics, thereby offering unprecedentedly high sensitivity and large Grasp (effective area times field-of-view). To complement this powerful monitoring ability, it also carries a narrow-field, sensitive followup X-ray telescope based on the same MPO technology to perform follow-up observations of newly-discovered transients. Public transient alerts will be downlinked rapidly, so as to trigger multi-wavelength follow-up observations from the world-wide community. Over three of its 97-minute orbits almost the entire night sky will be sampled, with cadences ranging from 5 to 25 times per day. The scientific objectives of the mission are: to discover otherwise quiescent black holes over all astrophysical mass scales by detecting their rare X-ray transient flares, particularly tidal disruption of stars by massive black holes at galactic centers; to detect and precisely locate the electromagnetic sources of gravitational-wave transients; to carry out systematic surveys of Xray transients and characterise the variability of X-ray sources, such as high-redshift gamma-ray bursts, supernova shock breakouts, X-ray binaries of compact objects, gamma-ray bursts, active galactic nuclei and stellar coronal flares, etc. Einstein Probe has been selected as a candidate mission of priority (no further selection needed) in the Space Science Programme of the Chinese Academy of Sciences, aiming for launch around 2020.

Rates of Stellar Tidal Disruption

“…While the ongoing ZTF survey is expected to increase today's TDE sample by one order of magnitude, near-future optical and X-ray time domain surveys may increase our TDE inventory even further, into the thousands and possibly tens of thousands. Two upcoming space-based X-ray surveys, eROSITA (Merloni et al 2012, launched during the writing of this Chapter) and Einstein Probe (Yuan et al 2015, launch date note yet determined), hold particular promise. The Einstein Probe is expected to detect tens to hundreds of X-ray bright TDEs per year (Yuan et al 2015), while eROSITA predictions give a per-year detection rate ≈ 1000 ).…”

“…Two upcoming space-based X-ray surveys, eROSITA (Merloni et al 2012, launched during the writing of this Chapter) and Einstein Probe (Yuan et al 2015, launch date note yet determined), hold particular promise. The Einstein Probe is expected to detect tens to hundreds of X-ray bright TDEs per year (Yuan et al 2015), while eROSITA predictions give a per-year detection rate ≈ 1000 ). On the ground, the wide-field LSST optical survey (LSST Science Collaboration et al 2009) has long been recognized for its ability to detect thousands of TDEs per year (Strubbe and Quataert 2009;van Velzen et al 2011); the true detection rate depends on survey strategy, but one recent estimate predicted ≈ 3 − 6 × 10 3 TDEs per year.…”

Design of conical Wolter-I geometry with sectioned secondary mirrors for x-ray telescopes

“…The Einstein Probe (EP) mission 33 was proposed in 2012 and is one of the candidate missions for advanced study in the Chinese Academy of Sciences space science program. It will carry a follow-up X-ray Telescope (FXT) with a narrow field of view for observation, employing the conical Wolter-I geometry.…”

Perspectives on Gamma-Ray Burst Physics and Cosmology with Next Generation Facilities

“…The nominal mission lifetime is three years with a goal of five years. For a more detailed description of the scientific goals and instrumentation of EP, please refer to Yuan et al (2015).…”