Insights from multi-wavelength observations during high and low states of non-magnetic CVs

An accreting white dwarf displaying fast transitional mode switching

“…3). Although the ASAS-SN lightcurve indicates that TW Pic can undergo slow transitions from a high to a low state (and vice versa) on timescales of weeks to months as is observed in several other accreting white dwarfs 1,19,20 , the moding behaviour occurring on ≈30 minute timescales appears to be restricted to the more recent observations. The TESS Cycle 3 data also reveal the mode switching from the low to the high mode, occurring on a somewhat longer timescale of ≈12 hours (see Extended Data Fig.…”

“…Accreting white dwarfs are often found in close binary systems with orbital periods ranging from tens of minutes to several hours. In most cases, the accretion process is relatively steady, with significant modulations only occurring on time-scales of ≈days or longer 1,2 . Here, we report the discovery of abrupt drops in the optical luminosity of the accreting white dwarf binary system TW Pictoris by factors up to 3.5 on time-scales as short as 30 minutes.…”

Time domain astronomy with the THESEUS satellite

“…The mass transfer rate from the donor is believed to be constant in the standard accretion disk theory. However, a consistent picture of the aforementionend high/ low states in both nonmagnetic and MCVs is still missing [62,63]. In addition, a Fig.…”

Time Domain Astronomy with the THESEUS Satellite

“…The mass transfer rate from the donor is believed to be constant in the standard accretion disk theory. However, a consistent picture of the aforementionend high/low states in both nonmagnetic and MCVs is still missing [59,60]. In addition, a few systems observed in low states have revealed flare-like variability in X-rays, suggesting sporadic mass transfer enhancement events (e.g., [61]).…”