15-20 March 2020
Europe/Berlin timezone

Low level accretion activity in X-ray binaries

19 Mar 2020, 17:45



David Russell (New York University Abu Dhabi)


Low-mass X-ray binaries can lay dormant, remaining undetected for decades, until they are usually detected by X-ray monitoring satellites when they undergo bright outbursts. However, during these periods of quiescence between outbursts, low level accretion does occur but usually cannot be studied at X-ray energies due to their extremely low fluxes. We have been monitoring ~40-50 X-ray binaries with the Faulkes Telescopes / Las Cumbres Observatory (LCO) global robotic network for more than a decade. We find evidence for low level, variable accretion activity, long-term trends and jets being launched at 10^-6 - 10^-8 times the Eddington luminosity in some systems. Different activity states exist in quiescence. The X-ray spectra of quiescent X-ray binaries are described by a power law; different sources have slightly different spectra. eROSITA on SRG will achieve high S/N soft X-ray spectra of Galactic quiescent low-mass X-ray binaries. We wish to test if accretion activity (identified by our optical monitoring) correlates with the X-ray properties uncovered by eROSITA. I will also introduce our new real-time optical monitoring pipeline, the "X-ray Binary New Early Warning System (XB-NEWS)", which aims to detect and announce new X-ray binary outbursts within a day of first optical detection. We are now detecting the early stages of these outbursts with our optical telescopes, before they become bright enough for X-ray detection. This allows us to trigger X-ray and multi-wavelength campaigns during the very early stages of outbursts, to constrain the outburst triggering mechanism.

Primary author

David Russell (New York University Abu Dhabi)

Presentation Materials

There are no materials yet.
Your browser is out of date!

Update your browser to view this website correctly. Update my browser now