A radio jet from the optical and x-ray bright stellar tidal disruption flare ASASSN-14li

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Science  01 Jan 2016:
Vol. 351, Issue 6268, pp. 62-65
DOI: 10.1126/science.aad1182
  • Fig. 1

    Flare and host spectral energy distribution (SED). Shown is the first epoch of the series of Swift x-ray (unfolded spectrum) and broadband optical/UV observations of ASASSN-14li. These observations can each be described by a single black body with T = 7.7 × 105 K and T = 3.5 × 104 K, respectively (blue lines; width reflects uncertainty on the temperature). The SED of the host galaxy based on archival data (gray squares) shows no sign of star formation or an AGN as demonstrated by our best-fit synthetic galaxy spectrum (green line). The pre-flare x-ray limit is shown for both a black body spectrum of similar temperature as the current x-ray spectrum (gray solid line) and a standard power-law AGN spectrum (Γ = 1.9; gray dashed line).

  • Fig. 2 Multi-wavelength light curves of the tidal disruption flare ASASSN-14li.

    (A) Integrated soft x-ray (0.3 to 1 keV) luminosity and monochromatic (vLv) near-UV (UVW2-band) luminosity. A spline fit to the observed g-band light curve of the known tidal flare PS1-10jh (23), corrected for cosmological time dilation and scaled up by 15%, is shown for reference (solid line). The dashed gray line indicates a (tt0)–5/3 power law, the approximate theoretically expected fallback rate of the stellar debris for a disruption at t0. The normalization of the time axis [in Modified Julian Day (MJD)] is chosen to highlight that the (late-time) light curves are consistent with this power law (t0 = 56947 ± 2 MJD) (fig. S1). Error bars show the 1σ statistical uncertainty, often smaller than the marker size. (B) Monochromatic radio luminosity at 15.7 GHz (AMI) and 1.4 GHz (WSRT) of ASASSN-14li and our jet model (solid lines). The spectral indices during the two epochs of dual radio frequency coverage are –0.4 ± 0.1 and –0.6 ± 0.1 (first and second epoch, respectively). The two most stringent upper limits on the early-time 5-GHz emission of previous thermal TDFs (gray triangles) (table S4) were not sensitive enough to detect transient radio emission similar to ASASSN-14li.

Supplementary Materials

  • A radio jet from the optical and X-ray bright stellar tidal disruption flare ASASSN-14li

    S. van Velzen, G. E. Anderson, N. C. Stone, M. Fraser, T. Wevers, B. D. Metzger, P. G. Jonker, A. J. van der Horst, T. D. Staley, A. J. Mendez, J. C. A. Miller-Jones, S. T. Hodgkin, H. C. Campbell, R. P. Fender

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

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    • Figs. S1 and S2
    • Tables S1 to S5
    • Full Reference List

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