Lucy, AB and Sokoloski, JL and Munari, U and Roy, N and Kuin, NPM and Rupen, MP and Knigge, C and Darnley, MJ and Luna, GJM and Somogyi, P and Valisa, P and Milani, A and Sollecchia, U and Weston, JHS (2020) Regulation of accretion by its outflow in a symbiotic star: The 2016 outflow fast state of MWC 560. In: Monthly Notices of the Royal Astronomical Society (3). pp. 3107-3127.
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Abstract
How are accretion discs affected by their outflows? To address this question for white dwarfs accreting from cool giants, we performed optical, radio, X-ray, and ultraviolet observations of the outflow-driving symbiotic star MWC 560 (≡V694 Mon) during its 2016 optical high state.We tracked multi-wavelength changes that signalled an abrupt increase in outflow power at the initiation of a months-long outflow fast state, just as the optical flux peaked: (1) an abrupt doubling of Balmer absorption velocities; (2) the onset of a 20 μJy per month increase in radio flux; and (3) an order-of-magnitude increase in soft X-ray flux. Juxtaposing to prior X-ray observations and their coeval optical spectra, we infer that both high-velocity and lowvelocity optical outflow components must be simultaneously present to yield a large soft X-ray flux, which may originate in shocks where these fast and slow absorbers collide. Our optical and ultraviolet spectra indicate that the broad absorption-line gas was fast, stable, and dense (≳106.5 cm-3) throughout the 2016 outflow fast state, steadily feeding a lower density (≲105.5 cm-3) region of radio-emitting gas. Persistent optical and ultraviolet flickering indicate that the accretion disc remained intact. The stability of these properties in 2016 contrasts to their instability during MWC 560's 1990 outburst, even though the disc reached a similar accretion rate.We propose that the self-regulatory effect of a steady fast outflow from the disc in 2016 prevented a catastrophic ejection of the inner disc. This behaviour in a symbiotic binary resembles disc/outflow relationships governing accretion state changes in X-ray binaries. © 2020 The Author(s).
| Item Type: | Journal Article |
|---|---|
| Publication: | Monthly Notices of the Royal Astronomical Society |
| Publisher: | Oxford University Press |
| Additional Information: | The copyright for this article belongs to Oxford University Press |
| Keywords: | Density of gases; Ultraviolet spectroscopy, Accretion discs; Accretion: accretion disks; Binaries: symbiotic; Fast state; Optical-; Soft X-ray; Star: individual (MWC 560); Stars: individual: proxima Centauri; Stars: winds outflows; Symbiotic stars, White dwarfs |
| Department/Centre: | Division of Physical & Mathematical Sciences > Physics |
| Date Deposited: | 24 Jan 2023 09:46 |
| Last Modified: | 24 Jan 2023 09:46 |
| URI: | https://eprints.iisc.ac.in/id/eprint/79406 |
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