Investigating accretion disk – radio jet coupling across the stellar mass scale

Abstract

Abstract. Relationships between the X-ray and radio behavior of black hole X-ray binaries during outbursts have established a fundamental coupling between the accretion disks and radio jets in these systems. I begin by reviewing the prevailing paradigm for this disk-jet coupling, also highlighting what we know about similarities and differences with neutron star and white dwarf binaries. Until recently, this paradigm had not been directly tested with dedicated high-angular resolution radio imaging over entire outbursts. Moreover, such high-resolution monitoring campaigns had not previously targetted outbursts in which the compact object was either a neutron star or a white dwarf. Jet-disk coupling across the stellar mass scale 225Collimation Probe Of Transient X-Ray Binaries (JACPOT XRB) project, which aims to use high angular resolution observations to compare disk-jet coupling across the stellar mass scale, with the goal of probing the importance of the depth of the gravitational potential well, the stellar surface and the stellar magnetic field, on jet formation. Our team has recently concluded its first monitoring series, including (E)VLA, VLBA, X-ray, optical, and near-infrared observations of entire outbursts of the black hole candidate H 1743-322, the neutron star system Aquila X-1, and the white dwarf system SS Cyg. Here I present preliminary results from this work, largely confirming the current paradigm, but highlighting some intriguing new behavior, and suggesting a possible difference in the jet formation process between neutron star and black hole systems.

Dwarf nova-type cataclysmic variable stars are significant radio emitters

“…In the novalikes, the radio emission is non-thermal, and is consistent with synchrotron or coherent emission (Coppejans et al 2015). In the DN SS Cyg, the radio emission in outburst is explained as synchrotron emission from a transient jet (Körding et al 2008;Miller-Jones et al 2011;Russell et al 2016). We now discuss what type of radio emission is seen in our sample of DN.…”

“…They predicted that DN should show a synchrotron radio flare from a transient jet on the rise to outburst, and they detected this in the DN SS Cyg. Miller-Jones et al (2011) subsequently confirmed this behaviour in a separate outburst of SS Cyg, and Russell et al (2016) proved that the radio outbursts of SS Cyg undergo similar evolution from outburst to outburst. Based on the timing, variability, spectral indices and brightness temperatures of the radio emission, and multi-wavelength data, Körding et al (2008), Miller-Jones et al (2011) and Russell et al (2016) argue that the radio emission in SS Cyg is produced by a transient jet.…”

“…ciently bright to account for the discrepancy. SU UMa was variable in our observations, and high-amplitude flares have been detected in SS Cyg (Körding et al 2008;Miller-Jones et al 2011;Russell et al 2016). It is therefore possible that SU UMa could have flared to 1.3 mJy, but as the Effelsberg detection was made in observations averaged from two separate outbursts, a flare should have been averaged out in these data.…”

“…Only four DN (namely SU UMa, EM Cyg, TY PSc and SS Cyg) have been detected at radio wavelengths (Benz et al 1983;Benz & Guedel 1989;Körding et al 2008;Miller-Jones et al 2011;Russell et al 2016). The numerous other radio observations of DN in outburst yielded non-detections with upper-limits on the order of 0.1-0.3 mJy (Fuerst et al 1986;Benz & Guedel 1989;Echevarria 1987).…”

“…reconnections in the disc, reflection of electrons in the magnetic field near the surface of the white dwarf, or disruption of the magnetosphere (Fuerst et al 1986;Benz & Guedel 1989;Benz et al 1996). These coherent mechanisms have been ruled out for SS Cyg (Körding et al 2008;Miller-Jones et al 2011;Russell et al 2016). The radio emission from the novalike systems is either synchrotron or coherent emission (Coppejans et al 2015).…”