Intergalactic magnetic fields in Stephan's Quintet

TL;DR

This study uses radio observations to reveal large-scale magnetic fields in Stephan's Quintet, showing their significant role in intergalactic matter dynamics and magnetic properties of tidal dwarf galaxy candidates.

Contribution

First detailed radio polarization study of Stephan's Quintet revealing intergalactic magnetic fields and their impact on galaxy interactions.

Findings

Detected a large envelope of radio emission indicating intergalactic matter.

Estimated magnetic field strength in the intergalactic ridge as 11.0 ± 2.2 μG.

Found a strong, anisotropic magnetic field in the tidal dwarf galaxy candidate SQ-B.

Abstract

We present results of the VLA radio continuum total power and polarised intensity observations of Stephan's Quintet at 1.43 and 4.86 GHz along with complementary 4.85 and 8.35 GHz Effelsberg observations. Our study shows a large envelope of radio emission encompassing all the member galaxies and hence a large volume of intergalac- tic matter. Infall of the galaxy NGC 7318B produces a ridge of intergalactic, polarised emission, for which the magnetic field strength was estimated as 11.0 \pm 2.2 {\mu}G, with an ordered component of 2.6 \pm 0.8 {\mu}G. The energy density of the field within the ridge area is of the same order as estimates of the thermal component, implying a significant role of the magnetic field in the dynamics of the intergalactic matter. We also report that the tidal dwarf galaxy candidate SQ-B possesses a strong and highly anisotropic magnetic field with the total strength being equal to 6.5 \pm 1.9 {\mu}G and an ordered component reaching 3.5 \pm 1.2 {\mu}G, which is comparable to that found in normal-sized galaxies.