Sub-relativistic Outflow and Hours-Timescale Large-amplitude X-ray Dips during Super-Eddington Accretion onto a Low-mass Massive Black Hole in the Tidal Disruption Event AT2022lri

We present the tidal disruption event (TDE) AT2022lri, hosted in a nearby (\(\approx\!144\) Mpc) quiescent galaxy with a low-mass massive black hole (\(10^4\,M_\odot < M_{\rm BH} < 10^6\,M_\odot\)). AT2022lri belongs to the TDE-H+He subtype. More than 1 Ms of X-ray data were collected with NICER, Swift, and XMM-Newton from 187 d to 672 d after peak. The X-ray luminosity gradually declined from \(1.5\times 10^{44}\,{\rm erg\,s^{-1}}\) to \(1.5\times 10^{43}\,{\rm erg\,s^{-1}}\) and remains much above the UV and optical luminosity, consistent with a super-Eddington accretion flow viewed face-on. Sporadic strong X-ray dips atop a long-term decline are observed, with variability timescale of \(\approx\!0.5\) hr--1 d and amplitude of \(\approx\!2\)--8. When fitted with simple continuum models, the X-ray spectrum is dominated by a thermal disk component with inner temperature going from \(\sim\! 146\) eV to \(\sim\! 86\) eV. However, there are residual features that peak around 1 keV, which, in some cases, cannot be reproduced by a single broad emission line. We analyzed a subset of time-resolved spectra with two physically motivated models describing either a scenario where ionized absorbers contribute extra absorption and emission lines or where disk reflection plays an important role. Both models provide good and statistically comparable fits, show that the X-ray dips are correlated with drops in the inner disk temperature, and require the existence of sub-relativistic (0.1--0.3\(c\)) ionized outflows. We propose that the disk temperature fluctuation stems from episodic drops of the mass accretion rate triggered by magnetic instabilities or/and wobbling of the inner accretion disk along the black hole's spin axis.