ASASSN-15oi: A Rapidly Evolving, Luminous Tidal Disruption Event at 216 Mpc
| Autor: | Holoien, T. W. -S., Kochanek, C. S., Prieto, J. L., Grupe, D., Chen, Ping, Godoy-Rivera, D., Stanek, K. Z., Shappee, B. J., Dong, Subo, Brown, J. S., Basu, U., Beacom, J. F., Bersier, D., Brimacombe, J., Carlson, E. K., Falco, E., Johnston, E., Madore, B. F., Pojmanski, G., Seibert, M. |
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| Rok vydání: | 2016 |
| Předmět: | |
| Zdroj: | MNRAS 463 (2016), 3813-3828 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1093/mnras/stw2272 |
| Popis: | We present ground-based and Swift photometric and spectroscopic observations of the tidal disruption event (TDE) ASASSN-15oi, discovered at the center of 2MASX J20390918-3045201 ($d\simeq216$ Mpc) by the All-Sky Automated Survey for SuperNovae (ASAS-SN). The source peaked at a bolometric luminosity of $L\simeq1.3\times10^{44}$ ergs s$^{-1}$ and radiated a total energy of $E\simeq6.6\times10^{50}$ ergs over the first $\sim3.5$ months of observations. The early optical/UV emission of the source can be fit by a blackbody with temperature increasing from $T\sim2\times10^4$ K to $T\sim4\times10^4$ K while the luminosity declines from $L\simeq1.3\times10^{44}$ ergs s$^{-1}$ to $L\simeq2.3\times10^{43}$ ergs s$^{-1}$, requiring the photosphere to be shrinking rapidly. The optical/UV luminosity decline during this period is most consistent with an exponential decline, $L\propto e^{-(t-t_0)/\tau}$, with $\tau \simeq46.5$ days for $t_0\simeq57241.6$ (MJD), while a power-law decline of $L\propto (t-t_0)^{-\alpha}$ with $t_0\simeq57212.3$ and $\alpha=1.62$ provides a moderately worse fit. ASASSN-15oi also exhibits roughly constant soft X-ray emission that is significantly weaker than the optical/UV emission. Spectra of the source show broad helium emission lines and strong blue continuum emission in early epochs, although these features fade rapidly and are not present $\sim3$ months after discovery. The early spectroscopic features and color evolution of ASASSN-15oi are consistent with a TDE, but the rapid spectral evolution is unique among optically-selected TDEs. Comment: 18 pages, 13 figures, 5 tables. Photometric data presented in this submission are included as ancillary files. Manuscript updated to reflect changes made in the published version. For a brief video explaining this paper, see https://youtu.be/clYXbqAQ0u0 |
| Databáze: | arXiv |
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