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

Abstract

Her X-1 is an accreting neutron star in an intermediate-mass X-ray binary. Like low-mass X-ray binaries (LMXBs), it accretes via Roche-lobe overflow, but similar to many high-mass X-ray binaries containing a neutron star, 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 disk. We measure a radio flux density of $38.7\pm 4.8$ $\mu$Jy at $9$ GHz but can not 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 launcing of jets by neutron stars with strong magnetic fields.

5 pages, 2 figures; accepted for publication in MNRAS Letters

References in corpus (7)

• Modelling the behaviour of accretion flows in X-ray binaries
• Broad relativistic iron emission line observed in SAX J1808.4-3658
• Disk-jet coupling in low-luminosity accreting neutron stars
• HZ Her: Stellar Radius from X-ray Eclipse Observations, Evolutionary State and a New Distance
• The large-scale jet-powered radio nebula of Circinus X-1
• Magnetic Field Upper Limits for Jet Formation
• Jet quenching in the neutron star low-mass X-ray binary 1RXS J180408.9$-$342058

Cited by in corpus (9)

• Accretion disks and coronae in the X-ray flashlight
• A new radio census of neutron star X-ray binaries
• Hot disk of the Swift J0243.6+6124 revealed by Insight-HXMT
• Revisiting the archetypical wind accretor Vela X-1 in depth -- A case study of a well-known X-ray binary and the limits of our knowledge
• A re-establishing jet during an X-ray re-brightening of the Be/X-ray binary Swift J0243.6+6124
• Radio emission from colliding outflows in high-mass X-ray binaries with strongly magnetized neutron stars
• X-Ray Views of Galactic Accreting Pulsars in High-Mass X-Ray Binaries
• Optical IFU spectroscopy of a bipolar microquasar jet in NGC 300
• Constraining the origin of the long term periodicity of FRB 20180916B with Polarization Position Angle