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تسجيل مستخدم جديدPS18kh: A New Tidal Disruption Event with a Non-Axisymmetric Accretion Disk
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We present the discovery of PS18kh, a tidal disruption event (TDE) discovered at the center of SDSS J075654.53+341543.6 ($dsimeq322$ Mpc) by the Pan-STARRS Survey for Transients. Our dataset includes pre-discovery survey data from Pan-STARRS, the All-Sky Automated Survey for Supernovae (ASAS-SN), and the Asteroid Terrestrial-impact Last Alert System (ATLAS) as well as high-cadence, multi-wavelength follow-up data from ground-based telescopes and Swift, spanning from 56 days before peak light until 75 days after. The optical/UV emission from PS18kh is well-fit as a blackbody with temperatures ranging from $Tsimeq12000$ K to $Tsimeq25000$ K and it peaked at a luminosity of $Lsimeq8.8times10^{43}$ ergs s$^{-1}$. PS18kh radiated $E=(3.45pm0.22)times10^{50}$ ergs over the period of observation, with $(1.42pm0.20)times10^{50}$ ergs being released during the rise to peak. Spectra of PS18kh show a changing, boxy/double-peaked H$alpha$ emission feature, which becomes more prominent over time. We use models of non-axisymmetric accretion disks to describe the profile of the H$alpha$ line and its evolution. We find that at early times the high accretion rate leads the disk to emit a wind which modifies the shape of the line profile and makes it bell-shaped. At late times, the wind becomes optically thin, allowing the non-axisymmetric perturbations to show up in the line profile. The line-emitting portion of the disk extends from $r_{rm in}sim60r_{rm g}$ to an outer radius of $r_{rm out}sim1400r_{rm g}$ and the perturbations can be represented either as an eccentricity in the outer rings of the disk or as a spiral arm in the inner disk.
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