Probing the tidal disruption event iPTF16axa with CLOUDY and disc-wind models by T. Mageshwaran et al. on Tuesday 29 November

We present both a disc-wind model on the optical/UV emission continuum and

CLOUDY modelling on the spectral lines of the tidal disruption event (TDE)

iPTF16axa to understand the disc-wind emission and the properties of the

atmosphere that impacts the line luminosity of the TDE. Assuming the optical/UV

emission from the wind due to the disc super-Eddington phase, we use the steady

structured disc-wind model with a spherical wind with constant velocity to fit

the observations on multiple days. The extracted parameters are stellar-mass

$M_{\star} = 6.20 \pm 1.19 M_{\odot}$, disc radiative efficiency $\log_{\rm

10}(\eta) = -1.22 \pm 1.327$, wind inner radius $r_l = (2.013 \pm 0.551) \times

10^{14}~{\rm cm}$ and velocity $v_w = 18999.4 \pm 1785.1 ~{\rm km~s^{-1}}$. The

photosphere temperature for wind emission is $ \sim 2 \times 10^4~{\rm K}$ and

the disc single blackbody temperature is $\sim 0.995 \times 10^5~{\rm K}$. We

also perform CLOUDY modelling to explain the observed He and H line

luminosities that estimate a wind inner radius $r_l = 7.07 \times 10^{14}~{\rm

cm}$ and velocity $v_w = 1.3 \times 10^4~{\rm km~s^{-1}}$. The independent

analyses of iPTF16axa using CLOUDY and disc-wind models show comparable results

that agree with observations. The CLOUDY modelling finds that both the super

solar abundance of He and a smaller He II line optical depth is responsible for

the enhancement of He II line luminosity over the H$\alpha$ line luminosity.

The super-solar abundance of He II agrees with a relatively large stellar mass

and suggests that the disrupted star might have been a red giant.

arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.14458v1