Dwarf nova-type cataclysmic variable stars are significant radio emitters

Coppejans, D. L.; Körding, Elmar; Miller-Jones, J. C. A.; Rupen, M. P.; Sivakoff, G. R.; Knigge, Christian; Groot, P.; Woudt, P. A.; Waagen, Elizabeth O.; Templeton, Matthew R.

doi:10.1093/mnras/stw2133

Cited by 58 publications

(65 citation statements)

References 78 publications

(164 reference statements)

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“…The overall range of spectral indices for a power law fit (F ν ∝ ν α ) reported by Coppejans et al are −2.9 ± 1.5 to 4.2 ± 1.3 for the DNe [38], and −0.5 ± 0.7 to 1.7 ± 0.8 for the novalikes [40]. These are compatible with non-thermal synchrotron emission models, and consistent with emission from radio jets.…”

Section: Pos(heasa 2016)030supporting

confidence: 78%

“…The prototypical DN SS Cyg was observed with various facilities to exhibit reproducible radio flares during its recent outbursts ( [37] and references therein). The VLA detections of the DNe RX And, U Gem, Z Cam, SU UMa and YZ Cnc established that DNe as a class are indeed radio emitters during outburst [38]. Radio detections of four novalikes with the VLA have also been reported: V3885 Sgr [39], RW Sex, V603 Aql and TT Ari [40].…”

Section: Pos(heasa 2016)030mentioning

confidence: 82%

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Cataclysmic variables: New frontiers in multi-wavelength research

Odendaal¹,

Meintjes²

2017

Proceedings of 4th Annual Conference on High Energy Astrophysics in Southern Africa — PoS(HEASA 2016)

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Compact binary systems in which a white dwarf (WD) accretes material from a non-degenerate companion, constitute some of the most prevalent, yet intriguing astronomical objects in the universe. Of special interest is a class of these binaries known as cataclysmic variables (CVs), where the transfer of material from a red dwarf companion to the WD instigates a wide range of energetic processes causing transient, variable and eruptive behaviour. These binaries, as well as a closely related class of objects known as supersoft X-ray sources (SSSs) are therefore fascinating cosmic laboratories in which the effects of fundamentally important physical phenomena like turbulence, magnetic fields, gravitation, viscosity, and particle acceleration can be studied, by modelling the observed electromagnetic radiation, from the low energy radio waves all the way up to gammaray energies. Several CVs and SSSs have been shown to exhibit high-velocity outflows, many of which are expected to be driven by magnetic fields, and modern instruments have recently shown that these outflows are associated with radio and gamma-ray emission. These developments open up an exciting new area in this field. The upcoming commissioning of MeerKAT, as well as the newly available spectropolarimetric mode on SALT, in combination with international high-energy facilities, makes this the ideal time to undertake studies of the non-thermal emission in CVs in the form of synchrotron radio emission, and non-thermal optical emission, as well as potential particle acceleration yielding high energy emission.

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Section: Pos(heasa 2016)030supporting

confidence: 78%

Section: Pos(heasa 2016)030mentioning

confidence: 82%

Cataclysmic variables: New frontiers in multi-wavelength research

Odendaal¹,

Meintjes²

2017

Proceedings of 4th Annual Conference on High Energy Astrophysics in Southern Africa — PoS(HEASA 2016)

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“…Migliari & Fender 2006;Motta & Fender 2019), cataclysmic variables (e.g. Coppejans et al 2016;Mooley et al 2017) and other related sources (e.g. Corbel et al 2015) if and when they can be established to be optically thick.…”

Section: Discussionmentioning

confidence: 99%

Synchrotron self absorption and the minimum energy of optically thick radio flares from stellar mass black holes

Fender

Bright

2019

Monthly Notices of the Royal Astronomical Society

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We consider the case of radio flares from black hole X-ray binaries in which the flare spectrum evolves from optically thick to optically thin, under the assumption that this is due to decreasing optical depth to synchrotron self absorption. We are able to place upper and lower limits on the size of the emitting region associated with a radio flare, and determine the synchrotron source magnetic field and energy as a function of size. The energy has a clear minimum which occurs close to the condition that the magnetic field derived from synchrotron self absorption equals that calculated from equipartition. This minimum energy estimate is independent of the rise time of the event, and so may be applied to any event for which the peak flux is measured and there is evidence for self-absorption. This is a much more accurate approach to minimum energy estimation than assuming expansion at close to the speed of light. We apply this method to four examples of optically thick radio flares and find that in each case either the filling factor of the synchrotron source is considerably less than unity, or the expansion speed is considerably less than the speed of light. The combination of unity filling factor and expansion speeds close to the speed of light is completely ruled out on energetic grounds for three of the four events we consider. The inferred slowed expansion is consistent with detailed modelling of such events which has been recently reported in the literature. The minimum power requirements associated with the flares are found to be ∼ 10 36 erg s −1 , which are easily accomodated in the context of stellar mass black hole accretion at near-Eddington levels, when these flares typically occur. However, the true jet power could still be orders of magnitude higher.

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“…CVs are binary systems with a white dwarf primary accreting matter from Roche lobe overflow of the secondary star, usually a main-sequence star (e.g. Coppejans et al 2016). Dwarf novae from magnetic CVs have been observed to exhibit radio outbursts that can last for weeks, with rapid radio flaring on timescales less than an hour .…”

Section: Introductionmentioning

confidence: 99%

MKT J170456.2–482100: the first transient discovered by MeerKAT

Driessen

McDonald

Buckley

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We report the discovery of the first transient with MeerKAT, MKT J170456.2−482100, discovered in ThunderKAT images of the low mass X-ray binary GX339−4. MKT J170456.2−482100 is variable in the radio, reaching a maximum flux density of 0.71 ± 0.11 mJy on 2019 Oct 12, and is undetected in 15 out of 48 ThunderKAT epochs. MKT J170456.2−482100 is coincident with the chromospherically active Ktype sub-giant TYC 8332-2529-1, and ∼ 18 years of archival optical photometry of the star shows that it varies with a period of 21.25 ± 0.04 days. The shape and phase of the optical light curve changes over time, and we detect both X-ray and UV emission at the position of MKT J170456.2−482100, which may indicate that TYC 8332-2529-1 has large star spots. Spectroscopic analysis shows that TYC 8332-2529-1 is in a binary, and has a line-of-sight radial velocity amplitude of 43 km s −1 . We also observe a spectral feature in anti-phase with the K-type sub-giant, with a line-of-sight radial velocity amplitude of ∼ 12 ± 10 km s −1 , whose origins cannot currently be explained. Further observations and investigation are required to determine the nature of the MKT J170456.2−482100 system.

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Dwarf nova-type cataclysmic variable stars are significant radio emitters

Cited by 58 publications

References 78 publications

Cataclysmic variables: New frontiers in multi-wavelength research

Cataclysmic variables: New frontiers in multi-wavelength research

Synchrotron self absorption and the minimum energy of optically thick radio flares from stellar mass black holes

MKT J170456.2–482100: the first transient discovered by MeerKAT

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