Radio emission from the X-ray pulsar Her X-1: a jet launched by a strong magnetic field neutron star?

Her X-1 is an accreting neutron star (NS) in an intermediate-mass X-ray binary. Like lowmass X-ray binaries (LMXBs), it accretes via Roche lobe overflow, but similar to many high-mass X-ray binaries containing a NS; Her X-1 has a strong magnetic field and slow spin. Here, we present the discovery...

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Bibliographic Details
Main Authors: van den Eijnden, J., Degenaar, N., Russell, T., Miller-Jones, James, Wijnands, R., Miller, J., King, A., Rupen, M.
Format: Journal Article
Published: Oxford University Press 2018
Online Access:http://purl.org/au-research/grants/arc/FT140101082
http://hdl.handle.net/20.500.11937/69949
Description
Summary:Her X-1 is an accreting neutron star (NS) in an intermediate-mass X-ray binary. Like lowmass X-ray binaries (LMXBs), it accretes via Roche lobe overflow, but similar to many high-mass X-ray binaries containing a NS; Her X-1 has a strong magnetic field and slow spin. Here, we present the discovery of radio emission from Her X-1 with the Very Large Array. During the radio observation, the central X-ray source was partially obscured by a warped disc. We measure a radio flux density of 38.7 ± 4.8 µJy at 9 GHz but cannot constrain the spectral shape. We discuss possible origins of the radio emission, and conclude that coherent emission, a stellar wind, shocks and a propeller outflow are all unlikely explanations. A jet, as seen in LMXBs, is consistent with the observed radio properties. We consider the implications of the presence of a jet in Her X-1 on jet formation mechanisms and on the launching of jets by NSs with strong magnetic fields.