[Paper Review] The SVOM mission, a pathfinder for THESEUS

B. Cordier, D. Götz+1 more|arXiv (Cornell University)|Feb 5, 2018

Gamma-ray bursts and supernovae3 citations

TL;DR

This paper presents the SVOM mission as a pathfinder for the THESEUS space mission, demonstrating key technologies and systems—such as micro-pore optics, infrared detectors, and a global VHF alert network—for high-energy transient astronomy. By validating critical technologies and enabling rapid multi-wavelength follow-up of gamma-ray bursts, SVOM paves the way for THESEUS to achieve high-redshift GRB redshift determination and multi-messenger astronomy readiness by 2021–2022.

ABSTRACT

The Sino-French space mission SVOM (Space-based multi-band astronomical Variable Objects Monitor) is mainly designed to detect and localize Gamma-Ray Burst events (GRBs). The satellite, to be launched late 2021, embarks a set of gamma-ray, X-ray and optical imagers. Thanks to its pointing strategy, quick slew capability and fast data connection to earth, ground based observations with large telescopes will allow us to measure redshifts for an unprecedented sample of GRBs. We discuss here the overall science goals of the SVOM mission in the framework of the multi-wavelength and multi-messenger panorama of the next decade. Finally we show how some developments of the SVOM mission will be helpful for the THESEUS project.

Motivation & Objective

• To demonstrate the technological feasibility of key instruments for the THESEUS mission through the SVOM mission.
• To enable high-redshift gamma-ray burst (GRB) identification via rapid, multi-wavelength follow-up using space and ground-based telescopes.
• To support the development of a global alert network for transient events, reusable by future missions like THESEUS.
• To validate micro-pore optics (MPO) and large-format infrared detectors for future X-ray and infrared instrumentation.
• To prepare for multi-messenger astronomy by enabling joint detection of GRBs with gravitational waves, neutrinos, and very-high-energy photons.

Proposed method

• Utilizes a multi-instrumented satellite platform with wide-field (ECLAIRs) and narrow-field (MXT, VT, GRM) instruments for GRB detection and localization.
• Employs rapid autonomous slewing of the spacecraft to point narrow-field instruments toward GRB triggers within seconds of detection.
• Relies on a ground-based network of 45 VHF stations to broadcast GRB alerts within 30 seconds of on-board localization.
• Validates micro-pore optics (MPO) through breadboard and flight model testing, achieving TRL 7 by 2019 and TRL 9 by 2022.
• Deploys a European-made 2k×2k infrared detector (ALFA project) on the F-GFT telescope for sky testing and TRL advancement.
• Integrates real-time data processing and alert dissemination to enable prompt follow-up by large ground-based optical/infrared telescopes.

Experimental results

Research questions

• RQ1 How can SVOM’s technology and operations serve as a technological and operational pathfinder for the THESEUS mission?
• RQ2 To what extent can the micro-pore optics (MPO) developed for the MXT instrument be validated and scaled for use in the THESEUS/SXI telescope?
• RQ3 Can the ALFA project’s large-format infrared detector achieve flight readiness and demonstrate performance in space-like conditions before the THESEUS mission adoption?
• RQ4 How effective is the SVOM VHF alert network in enabling rapid global dissemination of GRB alerts, and to what extent can it be reused by THESEUS?
• RQ5 What is the expected performance of SVOM in detecting and localizing high-redshift GRBs and identifying counterparts to gravitational wave and high-energy neutrino events?

Key findings

• The MXT micro-pore optics achieved TRL 4–5 by July 2016, TRL 6 by summer 2018, TRL 7 by end-2019, TRL 8 by end-2020, and TRL 9 by early 2022, validating the technology for future use in THESEUS.
• The ALFA project’s 2k×2k infrared detector reached TRL 4 by 2019 and is expected to reach TRL 6 by 2021, supporting its potential use in the THESEUS IRT instrument.
• The SVOM VHF alert network, comprising 45 stations, broadcasts GRB alerts within 30 seconds of on-board localization for 2/3 of detected bursts.
• The MXT instrument is expected to localize 90% of GRB X-ray afterglows with 13″ accuracy in 50% of cases and detect sources down to ∼10⁻¹² erg cm⁻² s⁻¹ in 10 ks.
• The VT instrument achieves sub-arcsecond localization accuracy for GRBs up to redshift z = 6.5 with a V-band sensitivity of V = 22.5 in 300 seconds.
• SVOM is projected to detect and localize approximately 60 GRBs per year with ECLAIRs and 90 with GRM, enabling high-redshift GRB identification and cosmological studies.