The impact of accretion disc winds on the optical spectra of cataclysmic variables

J. H. Matthews*, C. Knigge, K. S. Long, S. A. Sim, N. Higginbottom

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

Many high-state non-magnetic cataclysmic variables (CVs) exhibit blueshifted absorption or P-Cygni profiles associated with ultraviolet (UV) resonance lines. These features imply the existence of powerful accretion disc winds in CVs. Here, we use our Monte Carlo ionization and radiative transfer code to investigate whether disc wind models that produce realistic UV line profiles are also likely to generate observationally significant recombination line and continuum emission in the optical waveband. We also test whether outflows may be responsible for the single-peaked emission line profiles often seen in high-state CVs and for the weakness of the Balmer absorption edge (relative to simple models of optically thick accretion discs). We find that a standard disc wind model that is successful in reproducing the UV spectra of CVs also leaves a noticeable imprint on the optical spectrum, particularly for systems viewed at high inclination. The strongest optical wind-formed recombination lines are H alpha and He ii lambda 4686. We demonstrate that a higher density outflow model produces all the expected H and He lines and produces a recombination continuum that can fill in the Balmer jump at high inclinations. This model displays reasonable verisimilitude with the optical spectrum of RW Trianguli. No single-peaked emission is seen, although we observe a narrowing of the double-peaked emission lines from the base of the wind. Finally, we show that even denser models can produce a single-peaked H alpha line. On the basis of our results, we suggest that winds can modify, and perhaps even dominate, the line and continuum emission from CVs.

Original languageEnglish
Pages (from-to)3331-3344
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Volume450
Issue number3
DOIs
Publication statusPublished - 01 Jul 2015

Keywords

  • accretion, accretion discs
  • line: profiles
  • radiative transfer
  • methods: numerical
  • novae, cataclysmic variables
  • stars: winds, outflows
  • UX URSAE MAJORIS
  • CARLO TRANSITION-PROBABILITIES
  • HOPKINS ULTRAVIOLET TELESCOPE
  • DRIVEN STELLAR WINDS
  • NOVA-LIKE VARIABLES
  • DWARF-NOVA
  • RW-TRI
  • LINE FORMATION
  • BZ CAMELOPARDALIS
  • IUE OBSERVATIONS

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