Shock breakouts from tidal disruption events

Abstract

Tidal disruption events of stars by supermassive black holes have so far been discovered months to years after the fact. In this paper we explore the short, faint and hard burst of radiation is emitted at maximum compression, as a result of shock breakout. The detection of this burst can be used to capture tidal disruption events in real time. We verify that shock breakout from main sequence stars produces radiation in the X-ray range, but find that it is difficult to detect using all sky X-ray surveying telescopes. In the case of shock breakout from red giants, most of the radiation is emitted in the UV and visible range, which is significantly easier to detect. A similar burst of UV/optical radiation will also be emitted by stars puffed by tidal heating from a previous passage close to the central black hole. This radiation can be detected by surveys like ZTF and LSST. We calculate detection rates for different types of galactic nuclei. For the case of a very full loss cone we predict a detection rate of once per month with LSST, whereas for the case of a very empty loss cone we predict a rate of once per year with LSST. Evidence from a recent tidal disruption event, ASASSN-14li, seems to favour a very full loss cone, in which case LSST is expected to detect one such event every month.

X-Ray Properties of TDEs

“…Alternatively, it is predicted that in some cases a shock occurs the star upon disruption which breaks out of the star and gives rise to a brief Xray flare (e.g. Yalinewich et al 2018). Finally, blazar-like variability in those TDEs where a relativistic jet launched from the near-vicinity of the black hole is pointing close to our line of sight can give rise to fast X-ray variability even for black holes more massive than IMBHs (e.g.…”

Disc formation from tidal disruption of stars on eccentric orbits by Kerr black holes using GRSPH

“…The initial pericentre passage is accompanied by a sharp spike in the energy injection rate (L shock ), corresponding to the shocks produced by the 'pancaking' of the star during its periapsis compression. This has been predicted to be observable as a brief Xray shock breakout with a peak luminosity between ∼ 10 40 -10 43 erg s −1 (Kobayashi et al 2004;Guillochon et al 2009;Yalinewich et al 2019), depending on the amount of energy lost as the shock moves out through the star. For β = 5, our calculations produce a spike of ∼ 10 46 erg s −1 , 3-6 orders of magnitude greater than the predicted X-ray luminosity, although this is only the energy dissipation rate and not a true luminosity.…”

Correction to: X-Ray Properties of TDEs

“…Data taken from Lin et al (2017a) predicted that in some cases a shock occurs the star upon disruption which breaks out of the star and gives rise to a brief X-ray flare (e.g. Yalinewich et al 2018). Finally, blazar-like variability in those TDEs where a relativistic jet launched from the near-vicinity of the black hole is pointing close to our line of sight can give rise to fast X-ray variability even for black holes more massive than IMBHs (e.g.…”