White dwarfs stripped by massive black holes: sources of coincident gravitational and electromagnetic radiation

Abstract

White dwarfs inspiralling into black holes of mass MBH≳ 105 M⊙ are detectable sources of gravitational waves in the Laser Interferometer Space Antenna (LISA) band. In many of these events, the white dwarf begins to lose mass during the main observational phase of the inspiral. The mass‐loss starts gently and can last for thousands of orbits. The white dwarf matter overflows the Roche lobe through the L1 point at each pericentre passage and the mass‐loss repeats periodically. The process occurs very close to the black hole and the released gas can accrete, creating a bright source of radiation with luminosity close to the Eddington limit, L∼ 1043 erg s−1. This class of inspirals offers a promising scenario for dual detections of gravitational waves and electromagnetic radiation.

Low-mass White Dwarfs with Hydrogen Envelopes as a Missing Link in the Tidal Disruption Menu

“…Note that disruption is still possible for lower BH masses than shown in each region. We include mass-radius relationships for typical WDs from Zalamea et al (2010), MS stars from Tout et al (1996), evolved stars from Bressan et al (2012Bressan et al ( , 2013, and sub-stellar objects from the 1 Gyr curve of Chabrier et al (2009). We define MS stars as M ≥ 0.085 M , brown dwarfs as 0.085 M > M ≥ 13 MJup, and planets as M < 13 MJup.…”

“…Theoretical studies of stellar structure and fallback rate began with Lagrangian (Evans & Kochanek 1989) and Eulerian (Khokhlov et al 1993) calculations, and have evolved to include detailed studies of MS stars (Lodato et al 2009;, giant planets (Guillochon et al 2011;Liu et al 2013), white dwarfs (Luminet & Pichon 1989;Kobayashi et al 2004;Rosswog et al 2008aRosswog et al ,b, 2009Zalamea et al 2010;Clausen & Eracleous 2011;Krolik & Piran 2011;Haas et al 2012;Cheng & Bogdanović 2014;MacLeod et al 2014MacLeod et al , 2016aVick et al 2016), and giant stars (MacLeod et al 2012(MacLeod et al , 2013.…”

Does Explosive Nuclear Burning Occur in Tidal Disruption Events of White Dwarfs by Intermediate-mass Black Holes?

“…We focus on the possibility of the WD TDE observed as an optical transient resulting from its thermonuclear explosion, although there are many studies for possible signatures of WD TDEs as other types of transients (Zalamea et al 2010;Clausen & Eracleous 2011;Haas et al 2012;MacLeod et al 2014;Cheng & Bogdanović 2014;East 2014;Shiokawa et al 2015;Ioka et al 2016). In a WD TDE, the WD is heated by compression in the direction perpendicular to the orbital plane.…”

Relativistic cross sections of tidal disruption events

“…Alternatively, in the empty loss cone regime a star may experience a number of 'grazing' encounters with the black hole losing a small fraction of mass during every encounter. This could lead to a recurring activity in galactic centres, see a discussion of a similar effect of tidal interaction of a white dwarf with an intermediate mass black hole in [12]. 3) I have considered only 'the first passage' problem assuming that the star is in its unperturbed state before the tidal encounter.…”