Shocks in the symbiotic recurrent nova V3890 Sgr: VLBI radio imaging and Fermi GeV gamma-rays
Journal article, 2026
We present very long baseline interferometric (VLBI) radio imaging and Fermi/LAT GeV gamma -ray observations of the 2019 eruption of the symbiotic recurrent nova V3890 Sgr. The VLBI imaging spans 8-51 d after the eruption, synchronous with the detected gamma -rays. VLBI imaging shows the eruption begins asymmetrically on day 8 and becomes rather circularly symmetric by day 32. This morphological evolution is explained by interaction with circumstellar material (CSM) com-prised of a spherical wind plus an overdensity in the orbital plane. Comparing radio images to optical line widths gives an expansion parallax distance of 6.8 kpc. In the first 32 d of eruption, VLBI images capture >80 per cent of the integrated flux implying that synchrotron emission dominates. A second peak in the VLA light curve is explained by an image on day 48 that reveals the nova shell surrounded by a diffuse synchrotron halo. The gamma -rays appear around optical maximum and remain detectable for 23 d; marginally significant gamma -rays reappear around day 60, concurrent with the second radio peak. Modelling indicates radio and gamma -ray emission arise in distinct shock regions: gamma -rays from CSM in the orbital plane, radio from the spherical CSM component. X-ray observations constrain the spherical CSM density, which is higher than in other symbiotic recurrent novae. Assuming equipartition, we estimate the fraction of the post-shock pressure in magnetic fields,is an element of(B) =few & times;10(-3).
radio continuum: transients
acceleration of particles
gamma-rays: stars
binaries: symbiotic
stars: individual: V3890 Sgr
novae, cataclysmic variables
Author
Isabella Molina
Michigan State University
Peter Craig
Michigan State University
Rebecca Diesing
Columbia University
Institute for Advanced Study
Laura Chomiuk
Michigan State University
Justin D. Linford
National Radio Astronomy Observatory
Brian D. Metzger
Columbia University
Flatiron Institute
Jun Yang
Chalmers, Space, Earth and Environment, Onsala Space Observatory
Brandon Benavente
Michigan State University
Kim L. Page
University Of Leicester
Kirill V. Sokolovsky
University of Illinois
Elias Aydi
Texas Tech University
Amy J. Mioduszewski
National Radio Astronomy Observatory
Koji Mukai
National Aeronautics and Space Administration (NASA)
University of Maryland
Miriam M. Nyamai
Joint Institute for VLBI in Europe (JIVE)
Michael P. Rupen
National Research Council Canada
J. l. Sokoloski
Columbia University
Montana N. Williams
New Mexico Institute of Mining and Technology
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 552 4 stag1851RadioNet 4
European Commission (EC) (EC/H2020/730562), 2017-01-01 -- 2020-12-31.
Subject Categories (SSIF 2025)
Astronomy, Astrophysics, and Cosmology
Subatomic Physics
DOI
10.1093/mnras/stag1851
Related datasets
Radio images [dataset]
URI: https://zenodo.org/records/18988180