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Thomas Bensby. Profile photo.

Thomas Bensby

Senior lecturer

Thomas Bensby. Profile photo.

WEAVE First Light Observations: Origin and Dynamics of the Shock Front in Stephan's Quintet

Author

  • M.I. Arnaudova
  • T. Bensby
  • C. C. Worley

Summary, in English

We present a detailed study of the large-scale shock front in Stephan’s Quintet, a by-product of past and ongoing interactions. Using integral-field spectroscopy from the new William Herschel Telescope Enhanced Area Velocity Explorer (WEAVE), recent 144 MHz observations from the LOFAR Two-metre Sky Survey, and archival data from the Very Large Array and JWST, we obtain new measurements of key shock properties and determine its impact on the system. Harnessing the WEAVE large integral field unit’s field of view (90 × 78 arcsec2), spectral resolution (R ∼ 2500), and continuous wavelength coverage across the optical band, we perform robust emission-line modelling and dynamically locate the shock within the multiphase intergalactic medium with higher precision than previously possible. The shocking of the cold gas phase is hypersonic, and comparisons with shock models show that it can readily account for the observed emission-line ratios. In contrast, we demonstrate that the shock is relatively weak in the hot plasma visible in X-rays (with Mach number of M ∼ 2–4), making it inefficient at producing the relativistic particles needed to explain the observed synchrotron emission. Instead, we propose that it has led to an adiabatic compression of the medium, which has increased the radio luminosity 10-fold. Comparison of the Balmer line-derived extinction map with the molecular gas and hot dust observed with JWST suggests that pre-existing dust may have survived the collision, allowing the condensation of H2 – a key channel for dissipating the shock energy. © 2024 The Author(s).

Department/s

  • Astrophysics

Publishing year

2024

Language

English

Pages

2269-2290

Publication/Series

Monthly Notices of the Royal Astronomical Society

Volume

535

Issue

3

Document type

Journal article

Publisher

Oxford University Press

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • galaxies: groups: individual: Stephan’s Quintet
  • galaxies: interactions
  • radio continuum: ISM
  • techniques: imaging spectroscopy
  • Atomic emission spectroscopy
  • Collisional plasmas
  • Emission lines
  • Galaxies: interactions
  • Galaxy group
  • Galaxy: group: individual: stephan’s quintet
  • Integral Field Spectroscopy
  • Large-scales
  • Radio continuum: ISM
  • Shock fronts
  • Techniques: imaging spectroscopies
  • William herschel telescopes
  • Hypersonic aerodynamics

Status

Published

ISBN/ISSN/Other

  • ISSN: 0035-8711