Discovery of an outflow from radio observations of the tidal disruption event ASASSN-14li

Kate D. Alexander; Edo Berger; James Guillochon; Bevin A. Zauderer; Peter K. G. Williams

doi:10.3847/2041-8205/819/2/L25

paper

Discovery of an outflow from radio observations of the tidal disruption event ASASSN-14li

arXiv:1510.01226 · doi:10.3847/2041-8205/819/2/L25

Abstract

We report the discovery of transient radio emission from the nearby optically-discovered TDE ASASSN-14li (distance of 90 Mpc), making it the first typical TDE detected in the radio, and unambiguously pointing to the formation of a non-relativistic outflow with a kinetic energy of $\approx (4 - 10) \times 1 0^{47}$ erg, a velocity of $\approx 12, 000 - 36, 000$ km s $^{- 1}$ , and a mass of $\approx 3 \times 1 0^{- 5} - 7 \times 1 0^{- 4}$ M $_{⊙}$ . We show that the outflow was ejected on 2014 August 11--25, in agreement with an independent estimate of the timing of super-Eddington accretion based on the optical, UV, and X-ray observations, and that the ejected mass corresponds to about $1 - 10%$ of the mass accreted in the super-Eddington phase. The temporal evolution of the radio emission also uncovers the circumnuclear density profile, $ρ (R) \propto R^{- 2.5}$ on a scale of about 0.01 pc, a scale that cannot be probed via direct measurements even in the nearest SMBHs. Our discovery of radio emission from the nearest well-studied TDE to date, with a radio luminosity lower than all previous limits, indicates that non-relativistic outflows are ubiquitous in TDEs, and that future, more sensitive, radio surveys will uncover similar events.

10 pages, 6 figures, 2 tables; published in ApJ Letters. Fixes an error in our density calculation and expands discussion, major conclusions unchanged from previous version

Discovery of an outflow from radio observations of the tidal disruption event ASASSN-14li

Abstract

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