Revisiting Optical Tidal Disruption Events with iPTF16axa

By T. Hung, S. Gezari, N. Blagorodnova, Nathaniel Roth, S. B. Cenko, Shrinivas R. Kulkarni, A. Horesh, I. Arcavi, C. McCully, Lin Yan and 5 more. 2017

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We report the discovery by the intermediate Palomar Transient Factory (iPTF) of a candidate tidal disruption event (TDE) iPTF16axa at z = 0.108 and present its broadband photometric and spectroscopic evolution from three months of follow-up observations with ground-based telescopes and Swift. The light curve is well fitted with a t−5/3 decay, and we constrain the rise time to peak to be <49 rest-frame days after disruption, which is roughly consistent with the fallback timescale expected for the ∼5 × 106 M⊙ black hole inferred from the stellar velocity dispersion of the host galaxy. The UV and optical spectral energy distribution is well described by a constant blackbody temperature of T ∼ 3 × 104 K over the monitoring period, with an observed peak luminosity of 1.1 × 1044 erg s−1. The optical spectra are characterized by a strong blue continuum and broad He ii and Hα lines, which are characteristic of TDEs. We compare the photometric and spectroscopic signatures of iPTF16axa with 11 TDE candidates in the literature with well-sampled optical light curves. Based on a single-temperature fit to the optical and near-UV photometry, most of these TDE candidates have peak luminosities confined between log(L [erg s−1]) = 43.4–44.4, with constant temperatures of a few ×104 K during their power-law declines, implying blackbody radii on the order of 10 times the tidal disruption radius, that decrease monotonically with time. For TDE candidates with hydrogen and helium emission, the high helium-to-hydrogen ratios suggest that the emission arises from high-density gas, where nebular arguments break down. We find no correlation between the peak luminosity and the black hole mass, contrary to the expectations for TDEs to have .

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/56227cbd36b9627099015bba7196aeebc4015372

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Citations in the corpus

The Final Season Reimagined: 30 Tidal Disruption Events from the ZTF-I Survey (2022, background): “…from the radio to the X-rays, with wide-field optical surveys at the forefront of these discoveries, including iPTF (Blagorodnova et al. 2017, 2019; Hung et al. 2017), ASAS-SN (Holoien et al. 2014, 2016a, 2016b, 2019b; Wevers et al. 2019; Hinkle et al. 2021a), Pan-STARRS (Gezari et al. 2012;…”
The fast, luminous ultraviolet transient AT2018cow: extreme supernova, or disruption of a star by an intermediate-mass black hole? (2018, background): “The similarity of the peak luminosity of AT2018cow to other UV/optical TDEs (Hung et al. 2017) and the expected energy dissipation rate from the circularization process of 1044(MBH/10 6M⊙) −1/6 erg s−1 (Piran et al. 2015) support this interpretation.”
Weighing Black Holes Using Tidal Disruption Events (2018, background): “…et al. 2014), PTF09djl (Arcavi et al. 2014), PTF09ge (Arcavi et al. 2014), iPTF16fnl (Blagorodnova et al. 2017; Brown et al. 2018), iPTF16axa (Hung et al. 2017), ASASSN-14li (Holoien et al. 2016b; Brown et al. 2017), ASASSN-15oi (Holoien et al. 2016a), ASASSN-14ae (Holoien et al. 2014; Brown…”
A Unified Model for Tidal Disruption Events (2018, background): “Luminosity: The luminosity estimate of several TDEs are a few×0.1LEdd (Hung et al. 2017).”